knowledge/categories/apps/etcd.md

etcd

etcd is a strongly consistent, distributed key-value store that provides a reliable way to store data that needs to be accessed by a distributed system or cluster of machines. It gracefully handles leader elections during network partitions and can tolerate machine failure, even in the leader node.

Tips

Make the k8s embedded single etcd to be a cluster

Unfortunately, there is no straightfoward way to change the existing embedded etcd to a cluster. But we can leverage etcd make-mirror command to replicate the existing etcd to a new cluster. The steps are:

1. Follow the guide to setup a new etcd cluster
2. Run the following command to replicate k8s emmbedded etcd data to the new cluster

sudo ETCDCTL_API=3 etcdctl make-mirror https://new_etcd_node:2379 --endpoints=https://192.168.1.2:2379  --cacert=/k8s_etcd/ca.crt   --cert=/k8s_etcd/server.crt   --key=/k8s_etcd/server.key   --dest-cacert=/new_etcd/ca.pem   --dest-cert=/new_etcd/etcd.pem   --dest-key=/new_etcd/etcd-key.pem

3. On one of the new cluster node, to verify the data

sudo ETCDCTL_API=3 etcdctl get --prefix=true "" -w json  --endpoints=https://127.0.0.1:2379   --cacert=/new_etcd/ca.pem   --cert=/new_etcd/etcd.pem   --key=/new_etcd/etcd-key.pem