mirror of
https://github.com/wahyd4/one-knowledge.git
synced 2026-08-09 05:06:40 +10:00
Initial import: links posts + github knowledge
This commit is contained in:
hermes
@@ -0,0 +1,21 @@
|
||||
---
|
||||
title: Aws
|
||||
created: 2020-01-06
|
||||
updated: 2020-01-06
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/aws.md
|
||||
---
|
||||
|
||||
## EC2
|
||||
Virtual machines
|
||||
|
||||
## ECS
|
||||
|
||||
Running and managing containers without worry about infrastructure
|
||||
|
||||
## Cloudfront
|
||||
|
||||
## S3
|
||||
|
||||
## RDS
|
||||
@@ -0,0 +1,219 @@
|
||||
---
|
||||
title: Docker
|
||||
created: 2021-02-08
|
||||
updated: 2021-02-08
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/docker.md
|
||||
---
|
||||
|
||||
# Docker
|
||||
|
||||
Easy to use, just drag and drop things.
|
||||
|
||||
## Benefits of using Docker
|
||||
|
||||
- Escape the app dependency matrix
|
||||
- Solve the environment issue. it works on my machine.
|
||||
- Very low resource allocation cost when compare with Virtual Machine. So on the same machine, you can run more containers and spend much less time.
|
||||
|
||||
## How Docker works
|
||||
|
||||
Very useful blog talking about how docker works internally: [Understanding the Docker Internals](https://medium.com/@nagarwal/understanding-the-docker-internals-7ccb052ce9fe)
|
||||
|
||||
|
||||
|
||||
Docker use
|
||||
|
||||
* Namespaces
|
||||
* Cgroups
|
||||
* Network
|
||||
* Union File Systems
|
||||
|
||||
to isolate all kinds of resources.
|
||||
|
||||
### Namespaces
|
||||
|
||||
Docker makes use of kernel namespaces to provide the isolated workspace called the container. When you run a container, Docker creates a set of namespaces for that container. These namespaces provide a layer of isolation. Each aspect of a container runs in a separate namespace and its access is limited to that namespace.
|
||||
Docker Engine uses the following namespaces on Linux:
|
||||
|
||||
- `PID` namespace for process isolation.
|
||||
- `NET` namespace for managing network interfaces.
|
||||
- `IPC` namespace for managing access to IPC resources.
|
||||
- `MNT` namespace for managing filesystem mount points.
|
||||
- `UTS` namespace for isolating kernel and version identifiers.
|
||||
- `USER` namespaces is a feature of Linux that can be used to separate the user IDs and group IDs between the host and containers. It can provide a better isolation and security: the privileged user root in the container can be mapped to a non-privileged user on the host.
|
||||
|
||||
#### How to see a docker container's namespaces
|
||||
|
||||
```bash
|
||||
> docker inspect 195de1a4b33c | grep Pid
|
||||
|
||||
"Pid": 1496,
|
||||
"PidMode": "",
|
||||
"PidsLimit": null,
|
||||
|
||||
> cd /proc/1496
|
||||
> ls
|
||||
|
||||
attr auxv clear_refs comm cpuset environ fd gid_map limits map_files mem mounts net numa_maps oom_score pagemap personality root schedstat setgroups smaps_rollup stat status task timerslack_ns wchan
|
||||
autogroup cgroup cmdline coredump_filter cwd exe fdinfo io loginuid maps mountinfo mountstats ns oom_adj oom_score_adj patch_state projid_map sched sessionid smaps stack statm syscall timers uid_map
|
||||
|
||||
> cd ns
|
||||
> ls
|
||||
|
||||
cgroup ipc mnt net pid pid_for_children user uts
|
||||
|
||||
```
|
||||
|
||||
### cgroups
|
||||
|
||||
|
||||
|
||||
Control Groups are a Linux feature for organizing processes in hierarchical groups and applying resources limits to them. Docker also makes use of kernel control groups for resource allocation and isolation. A cgroup limits an application to a specific set of resources. Control groups allow Docker Engine to share available hardware resources to containers and optionally enforce limits and constraints.
|
||||
Docker Engine uses the following cgroups:
|
||||
|
||||
- `Memory` cgroup for managing accounting, limits and notifications.
|
||||
- `HugeTBL` cgroup for accounting usage of huge pages by process group.
|
||||
- `CPU` cgroup for managing user / system CPU time and usage.
|
||||
- `CPUSet` cgroup for binding a group to specific CPU. Useful for real time applications and NUMA systems with localized memory per CPU.
|
||||
- `BlkIO` cgroup for measuring & limiting amount of blckIO by group.
|
||||
- `net_cls` and net_prio cgroup for tagging the traffic control.
|
||||
- `Devices` cgroup for reading / writing access devices.
|
||||
- `Freezer` cgroup for freezing a group. Useful for cluster batch scheduling, process migration and debugging without affecting prtrace.
|
||||
|
||||
### Union File Systems
|
||||
|
||||
|
||||
|
||||
|
||||
Union file systems operate by creating layers, making them very lightweight and fast. Docker Engine uses UnionFS to provide the building blocks for containers. Docker Engine can use multiple UnionFS variants, including AUFS, btrfs, vfs, and devicemapper.
|
||||
|
||||
### Container Format
|
||||
|
||||
Docker Engine combines the namespaces, control groups and UnionFS into a wrapper called a container format. The default container format is libcontainer.
|
||||
### Security
|
||||
|
||||
Docker Engine makes use of `AppArmor`, `Seccomp`, `Capabilities` kernel features for security purposes.
|
||||
|
||||
- `AppArmor` allows to restrict programs capabilities with per-program profiles.
|
||||
- `Seccomp` used for filtering syscalls issued by a program.
|
||||
- `Capabilties` for performing permission checks.
|
||||
|
||||
|
||||
### Docker VS VM
|
||||
|
||||
|
||||
|
||||
## Network
|
||||
|
||||
- Bridge
|
||||
- Host
|
||||
|
||||
## CMD
|
||||
|
||||
- has three forms
|
||||
- CMD ["executable","param1","param2"]
|
||||
- exec form, preferred
|
||||
- CMD ["param1","param2"]
|
||||
- as default parameters to ENTRYPOINT
|
||||
- CMD command param1 param2
|
||||
- shell form
|
||||
- The main purpose of a CMD is to provide defaults for an executing container. These defaults can include an executable, or they can omit the executable, in which case you must specify an ENTRYPOINT instruction as well.
|
||||
- If CMD is used to provide default arguments for the ENTRYPOINT instruction, both the CMD and ENTRYPOINT instructions should be specified with the JSON array format.
|
||||
- docker run could override the default specified in CMD.
|
||||
|
||||
## ENTRYPOINT
|
||||
|
||||
- docker run arguments will as the entrypoint’s parameters. not CMD’s override
|
||||
- has two forms
|
||||
- ENTRYPOINT ["executable", "param1", "param2"]
|
||||
- exec form, preferred
|
||||
- ENTRYPOINT command param1 param2
|
||||
- shell form
|
||||
- entrypoint setting can be override by docker run —entrypoint
|
||||
|
||||
## Security
|
||||
- https://docs.docker.com/engine/security/security/
|
||||
- use non root user
|
||||
- docker daemon attack surface
|
||||
- kernel security features
|
||||
|
||||
## Tips
|
||||
|
||||
### difference between `cmd` and `entrypoint`
|
||||
|
||||
`cmd` can be override but entrypoint can't.
|
||||
|
||||
### difference between `copy` and `add`
|
||||
|
||||
Basically they are similar, copy files and folder to destination. While ADD has some features (like local-only tar extraction and remote URL support) that are not immediately obvious. Consequently, the best use for ADD is local tar file auto-extraction into the image, as in ADD rootfs.tar.xz /.
|
||||
|
||||
### Reduce docker image size
|
||||
|
||||
- Use the small base docker image, e.g. `alpine`, `jessie` etc.
|
||||
- Change docker image to multi stage, only copy the runtime files and dependencies to the final stage
|
||||
|
||||
A example of node js one
|
||||
|
||||
**Before**
|
||||
|
||||
```Dockerfile
|
||||
FROM node:alpine as build FROM node as build
|
||||
|
||||
WORKDIR /app
|
||||
|
||||
# copy the app, note .dockerignore # copy the app, note .dockerignore
|
||||
COPY . /app
|
||||
|
||||
RUN apk update \
|
||||
&& apk add --no-cache git python alpine-sdk\
|
||||
&& npm ci \
|
||||
&& npm run build \
|
||||
&& npm run generate
|
||||
|
||||
EXPOSE 3000
|
||||
|
||||
CMD [ "npm", "start" ]
|
||||
|
||||
```
|
||||
**After**
|
||||
|
||||
```Dockerfile
|
||||
|
||||
FROM node as build
|
||||
|
||||
WORKDIR /app
|
||||
|
||||
# copy the app, note .dockerignore
|
||||
COPY . /app
|
||||
|
||||
RUN npm ci \
|
||||
&& npm run build \
|
||||
&& npm run generate \
|
||||
&& npm prune --production \
|
||||
&& curl -sf https://gobinaries.com/tj/node-prune | sh \
|
||||
&& node-prune
|
||||
|
||||
FROM node:alpine
|
||||
|
||||
WORKDIR /app
|
||||
|
||||
# copy from build image
|
||||
COPY --from=build /app ./
|
||||
|
||||
EXPOSE 3000
|
||||
|
||||
CMD [ "npm", "start" ]
|
||||
```
|
||||
|
||||
### Inspect image's files
|
||||
|
||||
First, just create a container instead of running a container.
|
||||
Then export the entire container to a zip file.
|
||||
|
||||
```
|
||||
docker create --name=some-name image:tag
|
||||
docker export tmp_$$ > some-name.zip
|
||||
docker rm some-name
|
||||
```
|
||||
@@ -0,0 +1,36 @@
|
||||
---
|
||||
title: Gcp
|
||||
created: 2019-11-27
|
||||
updated: 2019-11-27
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/gcp.md
|
||||
---
|
||||
|
||||
# Google Compute Engine
|
||||
|
||||
# Kubernetes Engine
|
||||
|
||||
# Cloud Storage
|
||||
|
||||
# Cloud SQL
|
||||
|
||||
# IAM
|
||||
|
||||
# Stackdriver
|
||||
|
||||
## Logging
|
||||
|
||||
## Log based metrics
|
||||
|
||||
## Debug
|
||||
|
||||
## Trace
|
||||
|
||||
# App Engine
|
||||
|
||||
# Cloud Functions
|
||||
|
||||
# Cloud Run
|
||||
|
||||
Run Containers without caring about infrastructure
|
||||
@@ -0,0 +1,49 @@
|
||||
---
|
||||
title: Incident
|
||||
created: 2018-03-27
|
||||
updated: 2018-03-27
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/incident.md
|
||||
---
|
||||
|
||||
# Incident Management
|
||||
|
||||
## Incident dealing
|
||||
|
||||
It's important for a company to have a formal process about how do people dealing with those scenarios. There should some places to list all the common issues and its' solutions.
|
||||
During the process, we should records the steps we have, so we can learn from this after the incident.
|
||||
Company should have a on call rotation rules to have every engineers on the list and well rotated.
|
||||
|
||||
### Some tools
|
||||
|
||||
* Pagerduty - on call scheduling and incident resolution
|
||||
* Datadog - metrics
|
||||
* Stackdriver - logging
|
||||
|
||||
## Incident Training
|
||||
|
||||
### The purpose for doing this
|
||||
|
||||
* It's better to have some training before people get on call
|
||||
* We can learn something from the incident training, so we can find some potential issues in production
|
||||
* It's a good opportunities to have people from different teams work together to solve the issue
|
||||
* Customer first. We should let customer know what happened if the issue has some impact to the customers.
|
||||
|
||||
### How to organise an incident training
|
||||
|
||||
* Have some check lists for people prepared before training
|
||||
* Have a almost production like environment to do this
|
||||
* Organiser triggers a issue, then ask trainees to fix the issue and investigate the root clause
|
||||
* Let customers knows what happened. The other way round, the customer can give us some more information and also give us some complaint about his loss due to the incident.
|
||||
* The on-call team should solve the issue as well as write down some notes to record how to deal with this.
|
||||
* Escalate the severity if necessary to involve more people to help to solve this
|
||||
* Give enough information to the next people when you are going to hand over it to.
|
||||
|
||||
## After incident
|
||||
|
||||
* Run a post incident review
|
||||
* Write down the incident events timeline
|
||||
* Provide a problem statement
|
||||
* List the root cause
|
||||
* List the ways of how do we prevent this happen again
|
||||
@@ -0,0 +1,792 @@
|
||||
---
|
||||
title: Kubernetes
|
||||
created: 2020-12-09
|
||||
updated: 2020-12-09
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/kubernetes.md
|
||||
---
|
||||
|
||||
# Kubernetes
|
||||
|
||||
## Terminology
|
||||
|
||||
### Pod
|
||||
|
||||
- Single container
|
||||
- Multiple containers
|
||||
- share ip
|
||||
- share volumes
|
||||
|
||||
#### Information you get when list pods
|
||||
|
||||
```bash
|
||||
➜ k get pods
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
cloud-sql-proxy-66d-71222342354s 1/1 Running 0 42d
|
||||
```
|
||||
|
||||
### Node
|
||||
|
||||
Basically is a Kubernetes client or agent which runs a bunch of pods.
|
||||
|
||||
### Service
|
||||
|
||||
- ClusterIP (default)
|
||||
- NodePort （ access by port）
|
||||
- LoadBalancer (external ip)
|
||||
- ExternalName dns
|
||||
|
||||
### Deployment
|
||||
|
||||
A Deployment provides declarative updates for Pods and ReplicaSets.
|
||||
|
||||
You describe a desired state in a Deployment, and the Deployment Controller changes the actual state to the desired state at a controlled rate. You can define Deployments to create new ReplicaSets, or to remove existing Deployments and adopt all their resources with new Deployments.
|
||||
|
||||
### Replica Set
|
||||
|
||||
A ReplicaSet’s purpose is to maintain a stable set of replica Pods running at any given time. As such, it is often used to guarantee the availability of a specified number of identical Pods.
|
||||
|
||||
### Service rolling update
|
||||
|
||||
### DaemonSet
|
||||
|
||||
Running that pod on every node.
|
||||
|
||||
- running a cluster storage daemon, such as `glusterd`, `ceph`, on each node
|
||||
- running a logs collection daemon on every node, such as `fluentd` or logstash.
|
||||
- running a node monitoring daemon on every node, such as Prometheus Node Exporter, collectd, New Relic agent.
|
||||
|
||||
### StatefulSet
|
||||
|
||||
|
||||
|
||||
StatefulSets represent a set of pods with unique, persistent identities and stable hostnames. The state information and other resilient data for any given StatefulSet Pod is maintained in persistent disk storage associated with the StatefulSet.
|
||||
|
||||
StatefulSets are designed to deploy stateful applications and clustered applications that save data to persistent storage, such as Google Compute Engine persistent disks. StatefulSets are suitable for deploying Kafka, MySQL, Redis, ZooKeeper, and other applications needing unique, persistent identities and stable hostnames. For stateless applications, use Deployments.
|
||||
|
||||
#### Key features
|
||||
|
||||
- Ordered, graceful deployment and scaling
|
||||
- Stable, persistent storage.
|
||||
- Stable, unique network identifiers.
|
||||
- Ordered, graceful deletion and termination.
|
||||
|
||||
#### An example
|
||||
|
||||
```yaml
|
||||
apiVersion: v1
|
||||
kind: Service
|
||||
metadata:
|
||||
name: nginx
|
||||
labels:
|
||||
app: nginx
|
||||
spec:
|
||||
ports:
|
||||
- port: 80
|
||||
name: web
|
||||
clusterIP: None
|
||||
selector:
|
||||
app: nginx
|
||||
---
|
||||
apiVersion: apps/v1
|
||||
kind: StatefulSet
|
||||
metadata:
|
||||
name: web
|
||||
spec:
|
||||
selector:
|
||||
matchLabels:
|
||||
app: nginx # Label selector that determines which Pods belong to the StatefulSet
|
||||
# Must match spec: template: metadata: labels
|
||||
serviceName: "nginx"
|
||||
replicas: 3
|
||||
template:
|
||||
metadata:
|
||||
labels:
|
||||
app: nginx # Pod template's label selector
|
||||
spec:
|
||||
terminationGracePeriodSeconds: 10
|
||||
containers:
|
||||
- name: nginx
|
||||
image: gcr.io/google_containers/nginx-slim:0.8
|
||||
ports:
|
||||
- containerPort: 80
|
||||
name: web
|
||||
volumeMounts:
|
||||
- name: www
|
||||
mountPath: /usr/share/nginx/html
|
||||
volumeClaimTemplates:
|
||||
- metadata:
|
||||
name: www
|
||||
spec:
|
||||
accessModes: [ "ReadWriteOnce" ]
|
||||
resources:
|
||||
requests:
|
||||
storage: 1Gi
|
||||
```
|
||||
|
||||
#### Update Statefulset
|
||||
|
||||
To decide how to handle updates, StatefulSets use a update strategy defined in spec: updateStrategy. There are two strategies, OnDelete and RollingUpdate:
|
||||
|
||||
- `OnDelete` does not automatically delete and recreate Pods when the object's configuration is changed. Instead, you must manually delete the old Pods to cause the controller to create updated Pods.
|
||||
|
||||
- `RollingUpdate` automatically deletes and recreates Pods when the object's configuration is changed. New Pods must be in Running and Ready states before their predecessors are deleted. With this strategy, changing the Pod specification automatically triggers a rollout. This is the default update strategy for StatefulSets.
|
||||
|
||||
StatefulSets update Pods in reverse ordinal order. You can monitor update rollouts by running the following command:
|
||||
|
||||
```bash
|
||||
kubectl rollout status statefulset [STATEFULSET_NAME]
|
||||
```
|
||||
#### Partitioning rolling updates
|
||||
|
||||
When you partition an update, all Pods with an ordinal greater than or equal to the partition value are updated when you update the StatefulSet’s Pod specification. Pods with an ordinal less than the partition value are not updated and, even if they are deleted, are recreated using the previous version of the specification. If the partition value is greater than the number of replicas, the updates are not propagated to the Pods.
|
||||
|
||||
### Proxy
|
||||
|
||||
Creates a proxy server or application-level gateway between localhost and the Kubernetes API Server. It also allows
|
||||
serving static content over specified HTTP path. All incoming data enters through one port and gets forwarded to the
|
||||
remote kubernetes API Server port, except for the path matching the static content path.
|
||||
|
||||
### DNS
|
||||
|
||||
- service.namespace
|
||||
|
||||
### Secrets
|
||||
|
||||
For storing keys, credentials and certificates. For instance: database token, 3rd party API keys.
|
||||
|
||||
### Persistent volumes
|
||||
|
||||
- Available
|
||||
- a free resource that is not yet bound to a claim
|
||||
- Bound
|
||||
- the volume is bound to a claim
|
||||
- Released
|
||||
- the claim has been deleted, but the resource is not yet reclaimed by the cluster
|
||||
- Failed
|
||||
- the volume has failed its automatic reclamation
|
||||
|
||||
### kubelet
|
||||
|
||||
The `kubelet` is the primary “node agent” that runs on each node. It can register the node with the apiserver using one of: the hostname; a flag to override the hostname; or specific logic for a cloud provider. The `kubelet` works in terms of a PodSpec
|
||||
|
||||
### CRD(CustomResourceDefinitions)
|
||||
|
||||
The CustomResourceDefinition API resource allows you to define custom resources. Defining a CRD object creates a new custom resource with a name and schema that you specify. The Kubernetes API serves and handles the storage of your custom resource.
|
||||
|
||||
| RDs | Aggregated API|
|
||||
|---|---|
|
||||
| Do not require programming. Users can choose any language for a CRD controller. | Requires programming in Go and building binary and image. Users can choose any language for a CRD controller.|
|
||||
| No additional service to run; CRs are handled by API Server. | An additional service to create and that could fail.|
|
||||
| No ongoing support once the CRD is created. Any bug fixes are picked up as part of normal Kubernetes Master upgrades. | May need to periodically pickup bug fixes from upstream and rebuild and update the Aggregated APIserver. |
|
||||
| No need to handle multiple versions of your API. For example: when you control the client for this resource, you can upgrade it in sync with the API. | You need to handle multiple versions of your API, for example: when developing an extension to share with the world. |
|
||||
|
||||
|
||||
### Liveness vs Readiness
|
||||
|
||||
#### Liveness
|
||||
|
||||
The `kubelet` uses liveness probes to know when to restart a Container. For example, liveness probes could catch a deadlock, where an application is running, but unable to make progress. Restarting a Container in such a state can help to make the application more available despite bugs.
|
||||
|
||||
The `kubelet` uses readiness probes to know when a Container is ready to start accepting traffic. A Pod is considered ready when all of its Containers are ready. One use of this signal is to control which Pods are used as backends for Services. When a Pod is not ready, it is removed from Service load balancers.
|
||||
|
||||
The kubelet uses startup probes to know when a Container application has started. If such a probe is configured, it disables liveness and readiness checks until it succeeds, making sure those probes don’t interfere with the application startup. This can be used to adopt liveness checks on slow starting containers, avoiding them getting killed by the kubelet before they are up and running.
|
||||
|
||||
```yaml
|
||||
apiVersion: v1
|
||||
kind: Pod
|
||||
metadata:
|
||||
name: goproxy
|
||||
labels:
|
||||
app: goproxy
|
||||
spec:
|
||||
containers:
|
||||
- name: goproxy
|
||||
image: k8s.gcr.io/goproxy:0.1
|
||||
ports:
|
||||
- containerPort: 8080
|
||||
readinessProbe:
|
||||
tcpSocket:
|
||||
port: 8080
|
||||
initialDelaySeconds: 5
|
||||
periodSeconds: 10
|
||||
livenessProbe:
|
||||
tcpSocket:
|
||||
port: 8080
|
||||
initialDelaySeconds: 15
|
||||
periodSeconds: 20
|
||||
```
|
||||
|
||||
#### Readiness
|
||||
|
||||
Sometimes, applications are temporarily unable to serve traffic. For example, an application might need to load large data or configuration files during startup, or depend on external services after startup. In such cases, you don’t want to kill the application, but you don’t want to send it requests either. Kubernetes provides readiness probes to detect and mitigate these situations. A pod with containers reporting that they are not ready does not receive traffic through Kubernetes Services.
|
||||
|
||||
```yaml
|
||||
readinessProbe:
|
||||
exec:
|
||||
command:
|
||||
- cat
|
||||
- /tmp/healthy
|
||||
initialDelaySeconds: 5
|
||||
periodSeconds: 5
|
||||
```
|
||||
|
||||
### Taints and Tolerations
|
||||
|
||||
Node affinity, described here, is a property of pods that attracts them to a set of nodes (either as a preference or a hard requirement). Taints are the opposite -- they allow a node to repel a set of pods.
|
||||
|
||||
Taints and tolerations work together to ensure that pods are not scheduled onto inappropriate nodes.
|
||||
|
||||
```bash
|
||||
kubectl taint nodes node1 key=value:NoSchedule
|
||||
```
|
||||
By default, no pod will be deploy to the node `node1`
|
||||
|
||||
You specify a toleration for a pod in the PodSpec. Both of the following tolerations “match” the taint created by the kubectl taint line above, and thus a pod with either toleration would be able to schedule onto node1:
|
||||
|
||||
```yaml
|
||||
tolerations:
|
||||
- key: "key"
|
||||
operator: "Equal"
|
||||
value: "value"
|
||||
effect: "NoSchedule"
|
||||
```
|
||||
|
||||
```yaml
|
||||
tolerations:
|
||||
- key: "key"
|
||||
operator: "Exists"
|
||||
effect: "NoSchedule"
|
||||
```
|
||||
|
||||
## Several ways to access a service inside Kubernetes cluster
|
||||
|
||||
* ClusterIP, Can only be accessed inside the cluster. You can access inside `kubectl proxy`
|
||||
* NodePort, You can access the service by a specific public port between `30000–32767`, if the cluster server IP changes, then your service' endpoint url changes.
|
||||
* LoadBalancer, it's kind of external service, all the requests go through the loadbalancer. Every service needs a new IP for this.
|
||||
* Ingress, can be shared among multiple services, you can have different types of ingress controllers: `gec`, `nginx`, `contour`, `istio` and so on.
|
||||
|
||||
Links:
|
||||
* [Kubernetes NodePort vs LoadBalancer vs Ingress? When should I use what?](https://medium.com/google-cloud/kubernetes-nodeport-vs-loadbalancer-vs-ingress-when-should-i-use-what-922f010849e0)
|
||||
|
||||
## Kubernetes components
|
||||
|
||||
A Kubernetes cluster consists of a set of worker machines, called nodes, that run containerized applications. Every cluster has at least one worker node.
|
||||
|
||||
The worker node(s) host the pods that are the components of the application. The Control Plane manages the worker nodes and the pods in the cluster. In production environments, the Control Plane usually runs across multiple computers and a cluster usually runs multiple nodes, providing fault-tolerance and high availability.
|
||||
|
||||
|
||||
|
||||
### Components
|
||||
|
||||
#### Control Plane Components
|
||||
|
||||
- `kube-apiserver` The API server is a component of the Kubernetes control plane that exposes the Kubernetes API. The API server is the front end for the Kubernetes control plane
|
||||
- `etcd` Consistent and highly-available key value store used as Kubernetes’ backing store for all cluster data.
|
||||
- `kube-scheduler` Control Plane component that watches for newly created pods with no assigned node, and selects a node for them to run on
|
||||
- `kube-controller-manager` Control Plane component that runs controller processes. These controllers include:
|
||||
|
||||
* Node Controller: Responsible for noticing and responding when nodes go down.
|
||||
* Replication Controller: Responsible for maintaining the correct number of pods for every replication controller object in the system.
|
||||
* Endpoints Controller: Populates the Endpoints object (that is, joins Services & Pods).
|
||||
* Service Account & Token Controllers: Create default accounts and API access tokens for new namespaces.
|
||||
- `cloud-controller-manager` runs controllers that interact with the underlying cloud providers
|
||||
|
||||
#### Node Components
|
||||
|
||||
Node components run on every node, maintaining running pods and providing the Kubernetes runtime environment.
|
||||
|
||||
- `kubelet` An agent that runs on each node in the cluster. It makes sure that containers are running in a pod. The kubelet takes a set of PodSpecs that are provided through various mechanisms and ensures that the containers described in those PodSpecs are running and healthy.
|
||||
- `kube-proxy` kube-proxy is a network proxy that runs on each node in your cluster, implementing part of the Kubernetes Service concept. kube-proxy maintains network rules on nodes. These network rules allow network communication to your Pods from network sessions inside or outside of your cluster.
|
||||
kube-proxy uses the operating system packet filtering layer if there is one and it’s available. Otherwise, kube-proxy forwards the traffic itself.
|
||||
- `Container Runtime` The container runtime is the software that is responsible for running containers.
|
||||
|
||||
#### Addons
|
||||
|
||||
Addons use Kubernetes resources (DaemonSet, Deployment, etc) to implement cluster features. Because these are providing cluster-level features, namespaced resources for addons belong within the kube-system namespace
|
||||
|
||||
- `DNS` While the other addons are not strictly required, all Kubernetes clusters should have cluster DNS, as many examples rely on it. Cluster DNS is a DNS server, in addition to the other DNS server(s) in your environment, which serves DNS records for Kubernetes services
|
||||
- `Web UI (Dashboard)` Dashboard is a general purpose, web-based UI for Kubernetes clusters.
|
||||
- `Container Resource Monitoring` Container Resource Monitoring records generic time-series metrics about containers in a central database, and provides a UI for browsing that data.
|
||||
- `Cluster-level Logging` A cluster-level logging mechanism is responsible for saving container logs to a central log store with search/browsing interface.
|
||||
|
||||
## Kubernetes pod lifecycle
|
||||
|
||||
Through its lifecycle, a Pod can attain following states:
|
||||
|
||||
- `Pending`: The pod is accepted by the Kubernetes system but its container(s) is/are not created yet.
|
||||
|
||||
- `Running`: The pod is scheduled on a node and all its containers are created and at-least one container is in Running state.
|
||||
|
||||
- `Succeeded`: All container(s) in the Pod have exited with status 0 and will not be restarted.
|
||||
|
||||
- `Failed`: All container(s) of the Pod have exited and at least one container has returned a non-zero status.
|
||||
|
||||
- `CrashLoopBackoff`: The container fails to start and is tried again and again.
|
||||
|
||||
## Creating Highly Available clusters with kubeadm
|
||||
|
||||
### With stacked control plane nodes
|
||||
|
||||
- `Init first control plane` kubeadm init --control-plane-endpoint "LOAD_BALANCER_DNS:LOAD_BALANCER_PORT" --upload-certs
|
||||
- `Join the rest control planes` kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 --control-plane --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07
|
||||
|
||||
### External etcd nodes
|
||||
|
||||
Setting up a cluster with external etcd nodes is similar to the procedure used for stacked etcd with the exception that you should setup etcd first, and you should pass the etcd information in the kubeadm config file.
|
||||
|
||||
|
||||
## Flow chart of running a pod
|
||||
|
||||
|
||||
|
||||
Chart from: <https://blog.heptio.com/core-kubernetes-jazz-improv-over-orchestration-a7903ea92ca>
|
||||
|
||||
## Kubernetes termination lifecycle
|
||||
|
||||
|
||||
|
||||
Chart from: <https://dzone.com/articles/kubernetes-lifecycle-of-a-pod>
|
||||
|
||||
## Zero down time deployment
|
||||
|
||||
Set strategy type to `RollingUpdate` instead of `Recreate`
|
||||
|
||||
```yaml
|
||||
spec:
|
||||
replicas: 1
|
||||
strategy:
|
||||
type: RollingUpdate
|
||||
rollingUpdate:
|
||||
maxUnavailable: 50%
|
||||
maxSurge: 1
|
||||
```
|
||||
|
||||
## Some useful commands
|
||||
|
||||
```bash
|
||||
kubectl config set-context context-name --namespace default-namespace-name #default active context
|
||||
kubectl config view #view config
|
||||
kubectl get nodes #get nodes
|
||||
kubectl get namespaces #get all namespaces
|
||||
kubectl get pods #get pods
|
||||
kubectl get deployments #get deployments
|
||||
kubectl logs -f <pod> --tail 200 # tail logs from some pod
|
||||
kubectl get services #get services
|
||||
kubectl get ingress #get ingresses
|
||||
kubectl get hpa # get horizontal auto scaling policies
|
||||
kubectl get all # get all kinds of units
|
||||
kubectl get secrets <secret-id> -o yaml #view a secret details with yaml format, fields are encrypted with base64
|
||||
# List all Secrets currently in use by a pod
|
||||
kubectl get pods -o json | jq '.items[].spec.containers[].env[]?.valueFrom.secretKeyRef.name' | grep -v null | sort | uniq
|
||||
|
||||
# List Events sorted by timestamp
|
||||
kubectl get events --sort-by=.metadata.creationTimestamp
|
||||
|
||||
kubectl run -i --tty busybox --image=busybox -- sh # Run pod as interactive shell
|
||||
kubectl run nginx --image=nginx --restart=Never -n
|
||||
mynamespace # Run pod nginx in a specific namespace
|
||||
kubectl run nginx --image=nginx --restart=Never # Run pod nginx and write its spec into a file called pod.yaml
|
||||
--dry-run -o yaml > pod.yaml
|
||||
|
||||
kubectl attach my-pod -i # Attach to Running Container and get the current running process
|
||||
|
||||
kubectl top pod POD_NAME --containers # Show metrics for a given pod and its containers
|
||||
|
||||
kubectl config view -o jsonpath='{.users[].name}' # display the first user
|
||||
kubectl config view -o jsonpath='{.users[*].name}' # get a list of users
|
||||
kubectl config get-contexts # display list of contexts
|
||||
kubectl config current-context # display the current-context
|
||||
kubectl config use-context my-cluster-name # set the default context to my-cluster-name
|
||||
|
||||
# add a new cluster to your kubeconf that supports basic auth
|
||||
kubectl config set-credentials kubeuser/foo.kubernetes.com --username=kubeuser --password=kubepassword
|
||||
|
||||
# permanently save the namespace for all subsequent kubectl commands in that context.
|
||||
kubectl config set-context --current --namespace=ggckad-s2
|
||||
|
||||
# set a context utilizing a specific username and namespace.
|
||||
kubectl config set-context gce --user=cluster-admin --namespace=foo \
|
||||
&& kubectl config use-context gce
|
||||
|
||||
kubectl config unset users.foo # delete user foo
|
||||
|
||||
kubectl describe quota # Check quota for current namespace
|
||||
|
||||
kubectl taint nodes node1 key=value:NoSchedule # add node taint
|
||||
kubectl taint nodes node1 key:NoSchedule- # remove a taint from a node
|
||||
|
||||
```
|
||||
|
||||
### Some explanation
|
||||
|
||||
#### kubectl exec with attach
|
||||
|
||||
The main difference is in the process you interact with in the container:
|
||||
|
||||
`exec`: any one you want to create
|
||||
|
||||
`attach`: the one currently running (no choice)
|
||||
|
||||
## Kubernetes port forward
|
||||
|
||||
`kubectl port-forward` allows using resource name, such as a pod name, to select a matching pod to port forward to Which is perfect for testing the remote service/pods in your local. e.g. Forward your db port to a local port, you can connect to your remote db even it doesn't have a public IP.
|
||||
|
||||
```bash
|
||||
kubectl port-forward redis-master-765d459796-258hz 7000:6379
|
||||
|
||||
kubectl port-forward pods/redis-master-765d459796-258hz 7000:6379
|
||||
|
||||
kubectl port-forward deployment/redis-master 7000:6379
|
||||
|
||||
kubectl port-forward rs/redis-master 7000:6379
|
||||
|
||||
kubectl port-forward svc/redis-master 7000:6379
|
||||
```
|
||||
|
||||
## Kubernetes Dashboard
|
||||
|
||||
### Deploy Dashboard
|
||||
|
||||
```bash
|
||||
kubectl create -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml
|
||||
```
|
||||
### Access dashboard
|
||||
|
||||
```bash
|
||||
# First fetch cluster info, make sure cluster is running properly
|
||||
kubectl cluster-info
|
||||
|
||||
# Normally the url for dashboard would be
|
||||
http://your_ip:8080/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/
|
||||
|
||||
```
|
||||
|
||||
## Configure Kubectl to access remote Kubernetes cluster
|
||||
|
||||
Here is a very simple config which use HTTP and `not secure`, should only for local testing purpose
|
||||
|
||||
### Config
|
||||
|
||||
Having a yaml file called `config-demo` in your current folder
|
||||
|
||||
```yaml
|
||||
apiVersion: v1
|
||||
clusters:
|
||||
- cluster:
|
||||
server: https://your_cluster_ip:5443
|
||||
name: development
|
||||
contexts:
|
||||
- context:
|
||||
cluster: development
|
||||
namespace: dev
|
||||
user: developer
|
||||
name: dev
|
||||
current-context: dev
|
||||
kind: Config
|
||||
preferences: {}
|
||||
users:
|
||||
- name: developer
|
||||
```
|
||||
|
||||
### Connect to remote cluster
|
||||
|
||||
```bash
|
||||
kubectl get all --kubeconfig=config-demo --all-namespaces
|
||||
```
|
||||
For long term usage, you will need to copy the content to your `~/.kube/config` file
|
||||
|
||||
## Helm
|
||||
|
||||
Add Kubernetes yaml template engine and the package manager for Kubernetes
|
||||
|
||||
### How to use
|
||||
|
||||
```bash
|
||||
helm init
|
||||
helm upgrade --install -f abc/values-staging.yaml some-name ./abc
|
||||
# abc/values-staging.yaml the value file
|
||||
# some-name the release name
|
||||
# abc the template folder
|
||||
helm delete --purge mqtt # mqtt the release name
|
||||
|
||||
```
|
||||
### Install 3rd party packages
|
||||
```bash
|
||||
helm repo add gitlab https://charts.gitlab.io/ # add remote repo
|
||||
helm repo update # update index
|
||||
helm install mirantisworkloads/vernemq
|
||||
```
|
||||
|
||||
### Tips
|
||||
|
||||
* Normally when you just updated the configmap the deployment or statefulset pod wouldn't updated, but you can add a label to deployment/statefulset yaml, when the value changes the pods will be recreated
|
||||
|
||||
```yaml
|
||||
template:
|
||||
metadata:
|
||||
labels:
|
||||
app: vernemq
|
||||
configmapVersion: "{{ .Release.Revision }}"
|
||||
```
|
||||
|
||||
### Deploy tools comparsion
|
||||
|
||||
https://blog.hasura.io/draft-vs-gitkube-vs-helm-vs-ksonnet-vs-metaparticle-vs-skaffold-f5aa9561f948/
|
||||
|
||||
## Rolling update
|
||||
|
||||
Readiness Probe. Readiness Probe makes sure that the new pods created are ready to take on requests before terminating the old pods. To enable this, first you need to have a route in whatever the application you want to run which would return a 200 on an HTTP GET (Or other type) request.
|
||||
|
||||
```yaml
|
||||
apiVersion: apps/v1
|
||||
kind: Deployment
|
||||
metadata:
|
||||
name: hello-dep
|
||||
namespace: default
|
||||
spec:
|
||||
replicas: 2
|
||||
strategy:
|
||||
type: RollingUpdate
|
||||
rollingUpdate:
|
||||
maxSurge: 1
|
||||
maxUnavailable: 25%
|
||||
selector:
|
||||
matchLabels:
|
||||
app: hello-dep
|
||||
template:
|
||||
metadata:
|
||||
labels:
|
||||
app: hello-dep
|
||||
spec:
|
||||
containers:
|
||||
- image: gcr.io/google-samples/hello-app:2.0
|
||||
imagePullPolicy: Always
|
||||
name: hello-dep
|
||||
ports:
|
||||
- containerPort: 8080
|
||||
readinessProbe:
|
||||
httpGet:
|
||||
path: /
|
||||
port: 8080
|
||||
initialDelaySeconds: 5
|
||||
periodSeconds: 5
|
||||
successThreshold: 1
|
||||
```
|
||||
`maxUnavailable` is an optional field that specifies the maximum number of Pods that can be unavailable during the update process. The value can be an absolute number (for example, 5) or a percentage of desired Pods (for example, 10%). The absolute number is calculated from percentage by rounding down. The value cannot be 0 if maxSurge is 0. The default value is 25%.
|
||||
|
||||
`maxSurge` is an optional field that specifies the maximum number of Pods that can be created over the desired number of Pods
|
||||
|
||||
`initialDelaySeconds`: Number of seconds after the container has started before readiness probes are initiated.
|
||||
|
||||
`periodSeconds`: How often (in seconds) to perform the probe. Default to 10 seconds. Minimum value is 1.
|
||||
|
||||
`timeoutSeconds`: Number of seconds after which the probe times out. Defaults to 1 second. Minimum value is 1.
|
||||
|
||||
`successThreshold`: Minimum consecutive successes for the probe to be considered successful after having failed. Defaults to 1. Must be 1 for liveness. Minimum value is 1.
|
||||
|
||||
`failureThreshold`: When a Pod starts and the probe fails, Kubernetes will try failureThreshold times before giving up. Giving up in case of liveness probe means restarting the Pod. In case of readiness probe the Pod will be marked Unready. Defaults to 3. Minimum value is 1.
|
||||
|
||||
## Horizontal scaling
|
||||
|
||||
### V1
|
||||
|
||||
```yaml
|
||||
apiVersion: autoscaling/v1
|
||||
kind: HorizontalPodAutoscaler
|
||||
metadata:
|
||||
name: worker-auto-scaling
|
||||
namespace: x-prod
|
||||
spec:
|
||||
scaleTargetRef:
|
||||
apiVersion: apps/v1
|
||||
kind: Deployment
|
||||
name: <deployment-name>
|
||||
minReplicas: 1
|
||||
maxReplicas: 2
|
||||
targetCPUUtilizationPercentage: 75 # trigger point
|
||||
```
|
||||
|
||||
### V2
|
||||
|
||||
```yaml
|
||||
apiVersion: autoscaling/v2beta2
|
||||
kind: HorizontalPodAutoscaler
|
||||
metadata:
|
||||
name: php-apache
|
||||
namespace: default
|
||||
spec:
|
||||
scaleTargetRef:
|
||||
apiVersion: apps/v1
|
||||
kind: Deployment
|
||||
name: php-apache
|
||||
minReplicas: 1
|
||||
maxReplicas: 10
|
||||
metrics:
|
||||
- type: Resource
|
||||
resource:
|
||||
name: cpu
|
||||
target:
|
||||
type: Utilization
|
||||
averageUtilization: 50
|
||||
- type: Pods
|
||||
pods:
|
||||
metric:
|
||||
name: packets-per-second
|
||||
target:
|
||||
type: AverageValue
|
||||
averageValue: 1k
|
||||
- type: Object
|
||||
object:
|
||||
metric:
|
||||
name: requests-per-second
|
||||
describedObject:
|
||||
apiVersion: networking.k8s.io/v1beta1
|
||||
kind: Ingress
|
||||
name: main-route
|
||||
target:
|
||||
type: Value
|
||||
value: 10k
|
||||
```
|
||||
## Limit CPU and memory for pods
|
||||
|
||||
```yaml
|
||||
ports:
|
||||
- name: db-port
|
||||
containerPort: 2345
|
||||
protocol: TCP
|
||||
resources:
|
||||
requests:
|
||||
cpu: 30m
|
||||
memory: 64Mi
|
||||
limits:
|
||||
cpu: 200m
|
||||
memory: 256Mi
|
||||
```
|
||||
|
||||
## Kubernetes Operator
|
||||
|
||||
A Kubernetes Operator is an abstraction for deploying non-trivial applications on Kubernetes. It wraps the logic for deploying and operating an application using Kubernetes constructs. As an example, the `etcd` operator provides an `etcd` cluster as a first-class object.
|
||||
|
||||
### An example Operator
|
||||
|
||||
- deploying an application on demand
|
||||
- taking and restoring backups of that application’s state
|
||||
-handling upgrades of the application code alongside related changes such as database schemas or extra configuration settings
|
||||
- publishing a Service to applications that don’t support Kubernetes APIs to discover them
|
||||
- simulating failure in all or part of your cluster to test its resilience
|
||||
- choosing a leader for a distributed application without an internal member election process
|
||||
|
||||
### Use Operator
|
||||
|
||||
```
|
||||
kubectl get SampleDB # find configured databases
|
||||
|
||||
kubectl edit SampleDB/example-database # manually change some settings
|
||||
```
|
||||
|
||||
### Some 3rd party operators
|
||||
|
||||
- Operator registry: https://operatorhub.io/
|
||||
- Custom operators list: https://gist.github.com/philips/a97a143546c87b86b870a82a753db14c
|
||||
- Prometheus operator: https://coreos.com/blog/the-prometheus-operator.html
|
||||
|
||||
## Debug on kubernetes
|
||||
|
||||
### Examine previous pod logs
|
||||
|
||||
View the container logs before crash
|
||||
|
||||
```bash
|
||||
kubectl logs --previous ${POD_NAME} ${CONTAINER_NAME}
|
||||
```
|
||||
|
||||
### Debug a pod
|
||||
|
||||
Let's assume you have a pod called test-app, but it doesn't have a shell or utility attched to it.
|
||||
|
||||
```bash
|
||||
kubectl debug -it ephemeral-demo --image=busybox --target=test-app
|
||||
```
|
||||
This can attach busybox to the target pod, so you can debug your pod with tools.
|
||||
|
||||
### Copy a pod
|
||||
|
||||
Sometimes Pod configuration options make it difficult to troubleshoot in certain situations, so we can copy the orginal pod to our debugging pod
|
||||
|
||||
```bash
|
||||
# source pod
|
||||
kubectl run myapp --image=busybox --restart=Never -- sleep 1d
|
||||
|
||||
kubectl debug myapp -it --image=ubuntu --share-processes --copy-to=myapp-debug
|
||||
```
|
||||
The --share-processes allows the containers in this Pod to see processes from the other containers in the Pod.
|
||||
|
||||
### Copy a pod with changing command or the image
|
||||
|
||||
```bash
|
||||
# You can use kubectl debug to create a copy of this Pod with the command changed to an interactive shell:
|
||||
|
||||
kubectl debug myapp -it --copy-to=myapp-debug --container=myapp -- sh
|
||||
|
||||
kubectl debug myapp --copy-to=myapp-debug --set-image=*=ubuntu
|
||||
```
|
||||
The syntax of --set-image uses the same container_name=image syntax as kubectl set image. *=ubuntu means change the image of all containers to ubuntu.
|
||||
|
||||
|
||||
|
||||
## Tools
|
||||
|
||||
### Kubectx and kubens
|
||||
|
||||
Switch faster between clusters and namespaces in kubectl https
|
||||
|
||||
- kubectx for switching contexts
|
||||
- kubens for switching namespaces
|
||||
|
||||
Github page: https://github.com/ahmetb/kubectx
|
||||
|
||||
|
||||
## Other distributions
|
||||
|
||||
### OpenShift(OKD)
|
||||
|
||||
https://github.com/openshift/okd
|
||||
|
||||
OKD is the Origin community distribution of Kubernetes optimized for continuous application development and multi-tenant deployment. OKD adds developer and operations-centric tools on top of Kubernetes to enable rapid application development, easy deployment and scaling, and long-term lifecycle maintenance for small and large teams. OKD is also referred to as Origin in github and in the documentation. OKD makes launching Kubernetes on any cloud or bare metal a snap, simplifies running and updating clusters, and provides all of the tools to make your containerized-applications succeed.
|
||||
|
||||
#### Differences
|
||||
|
||||
- More strict on security, for example you can't run docker images with `root` user.
|
||||
- Better UI and come with some management tools.
|
||||
- Integrated CI/CD
|
||||
- It's a Redhat product, OKD is its open-source project
|
||||
|
||||
|
||||
|
||||
|
||||
### K3s
|
||||
|
||||
https://github.com/rancher/k3s
|
||||
|
||||
k3s is intended to be a fully compliant Kubernetes distribution with the following changes:
|
||||
|
||||
1. Removed most in-tree plugins (cloud providers and storage plugins) which can be replaced
|
||||
with out of tree addons.
|
||||
2. Add sqlite3 as the default storage mechanism. etcd3 is still available, but not the default.
|
||||
3. Wrapped in simple launcher that handles a lot of the complexity of TLS and options.
|
||||
4. Minimal to no OS dependencies (just a sane kernel and cgroup mounts needed). k3s packages required
|
||||
dependencies
|
||||
* containerd
|
||||
* Flannel
|
||||
* CoreDNS
|
||||
* CNI
|
||||
* Host utilities (iptables, socat, etc)
|
||||
|
||||
|
||||
## Links
|
||||
|
||||
- https://kubernetes.io/docs/concepts/overview/components
|
||||
- [Writing a Custom Controller: Extending the Functionality of Your Cluster [I] - Aaron Levy](https://www.youtube.com/watch?v=_BuqPMlXfpE)
|
||||
- [kubectl docs](https://kubectl.docs.kubernetes.io/)
|
||||
@@ -0,0 +1,518 @@
|
||||
---
|
||||
title: Linux
|
||||
created: 2021-11-09
|
||||
updated: 2021-11-09
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/linux.md
|
||||
---
|
||||
|
||||
# Linux
|
||||
|
||||
## Useful commands and tips
|
||||
|
||||
### Split strings
|
||||
|
||||
```bash
|
||||
# split ip list string by comma and get first one
|
||||
export IP=127.0.0.2,127.0.0.3
|
||||
echo $IP | cut -d ',' -f1
|
||||
```
|
||||
|
||||
### Create a systemd service
|
||||
|
||||
Create a file called `/etc/systemd/system/hello.service`
|
||||
|
||||
```
|
||||
[Unit]
|
||||
Description=Hello Service
|
||||
After=network.target
|
||||
StartLimitIntervalSec=0
|
||||
[Service]
|
||||
Type=simple
|
||||
Restart=always
|
||||
RestartSec=1
|
||||
User=centos
|
||||
ExecStart=/app/hello.sh
|
||||
|
||||
[Install]
|
||||
WantedBy=multi-user.target
|
||||
```
|
||||
Automatically start the service when boot the vm
|
||||
|
||||
```bash
|
||||
sudo systemctl enable hello
|
||||
```
|
||||
|
||||
Start service
|
||||
|
||||
```bash
|
||||
sudo systemctl start hello
|
||||
```
|
||||
Learned from [here](https://medium.com/@benmorel/creating-a-linux-service-with-systemd-611b5c8b91d6)
|
||||
|
||||
### ssh
|
||||
Do not use default `22` port
|
||||
```bash
|
||||
ssh user@ip -p 22222
|
||||
```
|
||||
|
||||
Login without password
|
||||
|
||||
```bash
|
||||
# adds private key identities to the authentication agent
|
||||
ssh-add ~/.ssh/id_rsa
|
||||
|
||||
# use locally available keys to authorise logins on a remote machine
|
||||
|
||||
ssh-copy-id user@ip -p 22222
|
||||
```
|
||||
|
||||
### Add user to the sudo group
|
||||
|
||||
```bash
|
||||
usermod -aG sudo youruser
|
||||
```
|
||||
|
||||
### IP table
|
||||
|
||||
### Cron job
|
||||
|
||||
List cron jobs for current user
|
||||
|
||||
```bash
|
||||
crontab -l
|
||||
```
|
||||
|
||||
List cron jobs for some user
|
||||
|
||||
```bash
|
||||
crontab -u user -l
|
||||
```
|
||||
|
||||
Edit cron jobs
|
||||
|
||||
```bash
|
||||
crontab -e
|
||||
```
|
||||
|
||||
#### An example cron job
|
||||
|
||||
For example, you can run a backup of all your user accounts
|
||||
|
||||
```bash
|
||||
# at 5 a.m every week with:
|
||||
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
|
||||
```
|
||||
#### Check cron jobs logs
|
||||
|
||||
```bash
|
||||
grep CRON /var/log/syslog
|
||||
```
|
||||
|
||||
#### Cron job expression
|
||||
|
||||
`MIN HOUR DOM MON DOW`
|
||||
|
||||
Field Description Allowed Value
|
||||
MIN Minute field 0 to 59
|
||||
HOUR Hour field 0 to 23
|
||||
DOM Day of Month 1-31
|
||||
MON Month field 1-12
|
||||
DOW Day Of Week 0-6
|
||||
|
||||
### PS
|
||||
```bash
|
||||
ps aux | grep 'ruby'
|
||||
```
|
||||
List process, using `grep` to filter processes
|
||||
### tail
|
||||
Tailing texts from file in realtime
|
||||
|
||||
```bash
|
||||
tail -f a.log
|
||||
```
|
||||
`f` means following, auto append texts to console
|
||||
### nohup
|
||||
Simply running application in background
|
||||
|
||||
|
||||
### df
|
||||
```bash
|
||||
df -h
|
||||
```
|
||||
Show disk usage and left, `h` means show in human readable way. Normally by MB/GB.
|
||||
### free
|
||||
```bash
|
||||
total used free shared buff/cache available
|
||||
Mem: 3960624 416720 270024 22252 3273880 3264060
|
||||
Swap: 4104188 109688 3994500
|
||||
```
|
||||
Show memory usage and
|
||||
|
||||
### Watch
|
||||
```
|
||||
watch kubectl get pods
|
||||
```
|
||||
Continuous running the commands, watching the changes. By default it refresh the result every `2s`.
|
||||
|
||||
### Change timezone
|
||||
```bash
|
||||
TZ=Asia/Shanghai;
|
||||
ln -snf /usr/share/zoneinfo/$TZ /etc/localtime
|
||||
```
|
||||
|
||||
### Check release
|
||||
```bash
|
||||
cat /etc/*-release
|
||||
```
|
||||
|
||||
### Debian check system version
|
||||
```bash
|
||||
cat /etc/issue
|
||||
|
||||
cat /etc/debian_version
|
||||
```
|
||||
|
||||
### htop
|
||||
|
||||
like top, but more
|
||||
|
||||
#### mosh
|
||||
|
||||
auto reconnect ssh
|
||||
|
||||
### show last something time
|
||||
|
||||
```bash
|
||||
last shutdown
|
||||
last reboot
|
||||
```
|
||||
|
||||
### Count files in current folder
|
||||
|
||||
```bash
|
||||
find . -type f | wc -l
|
||||
```
|
||||
### Check if a port is open
|
||||
|
||||
Used Netcat
|
||||
|
||||
```bash
|
||||
if ! nc -z localhost 5672; then
|
||||
sleep 3;
|
||||
fi
|
||||
```
|
||||
|
||||
### scp copy files between host
|
||||
|
||||
#### Copy files from remote server
|
||||
|
||||
```bash
|
||||
scp your_username@remotehost.edu:foobar.txt /local/dir
|
||||
```
|
||||
|
||||
### Copy local files to remote server
|
||||
|
||||
```bash
|
||||
scp /path/to/local/file user@server:/path/to/remote/file
|
||||
```
|
||||
|
||||
### Merge video files into one
|
||||
|
||||
```bash
|
||||
ffmpeg -f concat -safe 0 -i ./files.txt -c copy output.mp4
|
||||
```
|
||||
|
||||
In the `files.txt` you should list all the video clips like the following
|
||||
|
||||
```txt
|
||||
file 1.flv
|
||||
file 2.flv
|
||||
file 3.flv
|
||||
```
|
||||
|
||||
### Curl
|
||||
|
||||
Curl is a very popular and powerful HTTP client, there is also another very good tool called `httpie` written in Python which is even eaiser to use.
|
||||
|
||||
The following are some useful commands:
|
||||
|
||||
#### Post request with file
|
||||
```bash
|
||||
curl --data "@$(pwd)/fixure/sample.json" --user "foo:bar" localhost:8080/api/abc
|
||||
```
|
||||
|
||||
### Mount
|
||||
|
||||
#### Mount NFS(Network file system) to local
|
||||
|
||||
```bash
|
||||
|
||||
mkdir /to-local-folder
|
||||
# mount
|
||||
mount -t nfs -O user=abc,pass=pass 192.168.1.2:/nfs-folder /to-local-folder
|
||||
|
||||
# remount
|
||||
mount -o remount /to-local-folder
|
||||
```
|
||||
|
||||
#### Mount folder permanently
|
||||
|
||||
In the example above, the mounted folder will lost the connection when you restart your system, in order to permanently mount the folder, you will need to edit `/etc/fstab` by adding one more line
|
||||
|
||||
```
|
||||
192.168.1.2:/nfs-folder /to-local-folder nfs defaults 0 0
|
||||
```
|
||||
You can specify more options
|
||||
|
||||
```
|
||||
192.168.0.216:/nfs-folder /to-local-folder nfs defaults,proto=tcp,port=2049 0 0
|
||||
```
|
||||
|
||||
### Rsync
|
||||
|
||||
Sync folders and files between folders and hosts
|
||||
|
||||
### sync between directories
|
||||
|
||||
```bash
|
||||
rsync -avzh /root/rpmpkgs /tmp/backups/
|
||||
```
|
||||
#### sync folders between hosts
|
||||
|
||||
```bash
|
||||
rsync -avz --exclude downloads --exclude 'some-folder' /mnt rsync://user@192.168.1.2/rsync/ -v -c
|
||||
```
|
||||
|
||||
You can export `RSYNC_PASSWORD` to pass password to the command.
|
||||
|
||||
#### Check rsync logs
|
||||
|
||||
```bash
|
||||
grep -ir rsync /var/log
|
||||
```
|
||||
|
||||
### Check debian version
|
||||
|
||||
```bash
|
||||
cat /etc/issue
|
||||
|
||||
cat /etc/debian_version
|
||||
```
|
||||
|
||||
### Debian error bash: netstat: command not found
|
||||
|
||||
```bash
|
||||
apt-get install net-tools
|
||||
```
|
||||
|
||||
### Create CPU loads
|
||||
|
||||
```bash
|
||||
dd if=/dev/urandom | gzip -9 >> /dev/null &
|
||||
```
|
||||
|
||||
### Kill the load process
|
||||
|
||||
```bash
|
||||
kill %1
|
||||
```
|
||||
|
||||
### IP Address
|
||||
|
||||
```bash
|
||||
sudo /sbin/ifconfig
|
||||
|
||||
ip address # new command
|
||||
```
|
||||
|
||||
### IP range, CIDR
|
||||
|
||||
```bash
|
||||
# ip range ,CIDR network
|
||||
|
||||
/16 /20 /24
|
||||
```
|
||||
|
||||
### trace route tool
|
||||
|
||||
```bash
|
||||
sudo apt-get install traceroute
|
||||
|
||||
sudo traceroute google.com -I
|
||||
```
|
||||
|
||||
### linux list all the service with status
|
||||
|
||||
```bash
|
||||
systemctl --full --type service --all
|
||||
```
|
||||
|
||||
### To see details about the RAM installed on your VM, run the following command:
|
||||
|
||||
```bash
|
||||
sudo dmidecode -t 17
|
||||
```
|
||||
|
||||
### verify the number of processors, run the following command:
|
||||
|
||||
```bash
|
||||
nproc
|
||||
```
|
||||
|
||||
### CPU information
|
||||
|
||||
```bash
|
||||
lscpu
|
||||
|
||||
# Check cpu platform
|
||||
|
||||
cat /proc/cpuinfo
|
||||
```
|
||||
|
||||
### Running application in background with screen
|
||||
|
||||
```bash
|
||||
sudo apt-get install -y screen
|
||||
|
||||
sudo screen -S mcs java -Xms1G -Xmx7G -d64 -jar /home/minecraft/minecraft_server.1.11.2.jar nogui
|
||||
|
||||
detach
|
||||
|
||||
# To detach the screen terminal, press Ctrl+A, D. The terminal continues to run in the background. To reattach the terminal, run the following command:
|
||||
|
||||
sudo screen -r mcs
|
||||
|
||||
# send commands to screen
|
||||
|
||||
sudo screen -r -X stuff '/stop\n'
|
||||
```
|
||||
|
||||
### ApacheBench To place a load on the load balancer, run the following command
|
||||
|
||||
```bash
|
||||
ab -n 50000 -c 1000 http://ip
|
||||
```
|
||||
|
||||
### Mount drives
|
||||
|
||||
```bash
|
||||
1. Find what the drive is called
|
||||
You'll need to know what the drive is called to mount it. To do that fire off one of the following (ranked in order of my preference):
|
||||
lsblk
|
||||
sudo blkid
|
||||
sudo fdisk -l
|
||||
You're looking for a partition that should look something like: /dev/sdb1. The more disks you have the higher the letter this is likely to be. Anyway, find it and remember what it's called.
|
||||
2. Create a mount point (optional)
|
||||
This needs to be mounted into the filesystem somewhere. You can usually use /mnt/ if you're being lazy and nothing else is mounted there but otherwise you'll want to create a new directory:
|
||||
sudo mkdir /media/usb
|
||||
3. Mount!
|
||||
sudo mount /dev/sdb1 /media/usb
|
||||
When you're done, just fire off:
|
||||
sudo umount /media/usb
|
||||
```
|
||||
|
||||
### Change dns server
|
||||
|
||||
```bash
|
||||
vim /etc/resolv.conf
|
||||
```
|
||||
|
||||
### Last boot
|
||||
|
||||
```bash
|
||||
last reboot | less
|
||||
last -x shutdown
|
||||
```
|
||||
|
||||
### Ports scanner
|
||||
|
||||
```bash
|
||||
#nmap scan ports
|
||||
nmap -v 203.192.94.53
|
||||
```
|
||||
|
||||
### Check and turn off swap
|
||||
|
||||
```bash
|
||||
# swap
|
||||
|
||||
1. Identify configured swap devices and files with cat /proc/swaps.
|
||||
2. Turn off all swap devices and files with swapoff -a.
|
||||
3. Remove any matching reference found in /etc/fstab.
|
||||
4. Optional: Destroy any swap devices or files found in step 1 to prevent their reuse. Due to your concerns about leaking sensitive information, you may wish to consider performing some sort of secure wipe.
|
||||
```
|
||||
|
||||
### Reset timezone
|
||||
|
||||
```bash
|
||||
sudo dpkg-reconfigure tzdata
|
||||
```
|
||||
|
||||
### List all timezones
|
||||
|
||||
```bash
|
||||
ls /usr/share/zoneinfo/
|
||||
|
||||
# check ssh failed retries
|
||||
|
||||
grep "Failed password" /var/log/auth.log
|
||||
```
|
||||
|
||||
### Linux disk analyse
|
||||
|
||||
```bash
|
||||
### Ncdu analyse linux disk
|
||||
|
||||
ncdu
|
||||
```
|
||||
|
||||
### VIM setup
|
||||
|
||||
```bash
|
||||
# https://github.com/amix/vimrc
|
||||
|
||||
git clone --depth=1 https://github.com/amix/vimrc.git ~/.vim_runtime
|
||||
sh ~/.vim_runtime/install_awesome_vimrc.sh
|
||||
```
|
||||
|
||||
### check ssh failed retries
|
||||
|
||||
```bash
|
||||
grep "Failed password" /var/log/auth.log
|
||||
|
||||
# In order to display extra information about the failed SSH logins, issue the command as shown in the below example.
|
||||
|
||||
egrep "Failed|Failure" /var/log/auth.log
|
||||
```
|
||||
|
||||
## Popular Distributions
|
||||
|
||||
### Debian
|
||||
|
||||
### Ubuntu
|
||||
|
||||
### Manjaro
|
||||
|
||||
### Fedora
|
||||
|
||||
Fedora is the main project, and it’s a community-based, free distro focused on quick releases of new features and functionality.
|
||||
|
||||
### CentOS
|
||||
|
||||
CentOS is basically the community version of Redhat. So it’s pretty much identical, but it is free and support comes from the community as opposed to Redhat itself.
|
||||
|
||||
### RHEL (RedHat Enterprise Linux)
|
||||
|
||||
|
||||
|
||||
|
||||
RHEL is the corporate version based on the progress of that project, and it has slower releases, comes with support, and isn’t free.
|
||||
|
||||
### Arch Linux
|
||||
|
||||
## Package manager
|
||||
|
||||
* [snap](https://snapcraft.io/)
|
||||
* [Brew](https://brew.sh/)
|
||||
@@ -0,0 +1,18 @@
|
||||
---
|
||||
title: More Tools
|
||||
created: 2021-11-04
|
||||
updated: 2021-11-04
|
||||
type: summary
|
||||
tags: [tech, reference]
|
||||
external: https://github.com/wahyd4/knowledge/blob/master/categories/devops/more-tools.md
|
||||
---
|
||||
|
||||
# More tools
|
||||
|
||||
## HTTP performace tests
|
||||
|
||||
Some command line toos which can provide categorized information for http requests.
|
||||
|
||||
* [curl_time](https://stackoverflow.com/questions/18215389/how-do-i-measure-request-and-response-times-at-once-using-curl?rq=1)
|
||||
* [hey](https://github.com/rakyll/hey)
|
||||
* [ab](https://httpd.apache.org/docs/2.4/programs/ab.html)
|
||||
Reference in New Issue
Block a user