loginsrv

loginsrv is a standalone minimalistic login server providing a JWT login for multiple login backends.

Abstract

Loginsrv provides a minimal endpoint for authentication. The login is performed against the providers and returned as Json Web Token. It can be used as:

• standalone microservice
• docker container
• golang library
• or as caddyserver plugin.

Supported Provider Backends

The following providers (login backends) are supported.

• Htpasswd
• Osiam
• Simple (user/password pairs by configuration)
• Oauth2
  • Github Login
  • .. google and facebook will come soon ..

Questions

For questions and support please use the Gitter chat room.

Configuration and Startup

Config Options

The configuration parameters are as follows.

  -cookie-http-only
        Set the cookie with the http only flag (default true)
  -cookie-name string
        The name of the jwt cookie (default "jwt_token")
  -github value
        Oauth config in the form: client_id=..,client_secret=..[,scope=..,][redirect_uri=..]
  -host string
        The host to listen on (default "localhost")
  -htpasswd value
        Htpasswd login backend opts: file=/path/to/pwdfile
  -jwt-secret string
        The secret to sign the jwt token (default "random key")
  -log-level string
        The log level (default "info")
  -login-path string
        The path of the login resource (default "/login")
  -logout-url string
        The url or path to redirect after logout
  -osiam value
        Osiam login backend opts: endpoint=..,client_id=..,client_secret=..
  -port string
        The port to listen on (default "6789")
  -simple value
        Simple login backend opts: user1=password,user2=password,..
  -success-url string
        The url to redirect after login (default "/")
  -template string
        An alternative template for the login form
  -text-logging
        Log in text format instead of json

Environment Variables

All of the above Config Options can also be applied as environment variable, where the name is written in the way: LOGINSRV_OPTION_NAME. So e.g. jwt-secret can be set by environment variable LOGINSRV_JWT_SECRET.

Startup examples

The most simple way to use loginsrv is by the provided docker container. E.g. configured with the simple provider:

$ docker run -d -p 80:80 tarent/loginsrv -jwt-secret my_secret -simple bob=secret

$ curl --data "username=bob&password=secret" 127.0.0.1/login
eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJib2IifQ.uWoJkSXTLA_RvfLKe12pb4CyxQNxe5_Ovw-N5wfQwkzXz2enbhA9JZf8MmTp9n-TTDcWdY3Fd1SA72_M20G9lQ

The same configuration could be written with enviroment variables in the way:

$ docker run -d -p 80:80 -e LOGINSRV_JWT_SECRET=my_secret -e LOGINSRV_BACKEND=provider=simple,bob=secret tarent/loginsrv

API

GET /login

Returns a simple bootstrap styled login form.

The returned html follows the ui composition conventions from (lib-compose)[https://github.com/tarent/lib-compose], so it can be embedded into an existing layout.

GET /login/

Starts the Oauth Web Flow with the configured provider. E.g. GET /login/github redirects to the github login form.

POST /login

Perfoms the login and returns the JWT. Depending on the content-type, and parameters a classical JSON-Rest or a redirect can be performed.

Runtime Parameters

Parameter-Type	Parameter	Description
Http-Header	Accept: text/html	Set the JWT-Token as Cookie 'jwt_token'.	default
Http-Header	Accept: application/jwt	Returns the JWT-Token within the body. No Cookie is set.
Http-Header	Content-Type: application/x-www-form-urlencoded	Expect the credentials as form encoded parameters.	default
Http-Header	Content-Type: application/json	Take the credentials from the provided json object.
Post-Parameter	username	The username
Post-Parameter	password	The password

Possible Return Codes

Code	Meaning	Description
200	OK	Successfully authenticated
403	Forbidden	The Credentials are wrong
400	Bad Request	Missing parameters
500	Internal Server Error	Internal error, e.g. the login provider is not available or failed
303	See Other	Sets the JWT as a cookie, if the login succeeds and redirect to the urls provided in redirectSuccess or redirectError

Hint: The status 401 Unauthorized is not used as a return code to not conflict with an Http BasicAuth Authentication.

DELETE /login

Deletes the JWT Cookie.

For simple usage in web applications, this can also be called by GET|POST /login?logout=true

API Examples

Example:

Default is to return the token as Content-Type application/jwt within the body.

curl -i --data "username=bob&password=secret" http://127.0.0.1:6789/login
HTTP/1.1 200 OK
Content-Type: application/jwt
Date: Mon, 14 Nov 2016 21:35:42 GMT
Content-Length: 100

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJib2IifQ.-51G5JQmpJleARHp8rIljBczPFanWT93d_N_7LQGUXU

Example: Credentials as JSON

The Credentials also could be send as JSON encoded.

curl -i -H 'Content-Type: application/json'  --data '{"username": "bob", "password": "secret"}' http://127.0.0.1:6789/login
HTTP/1.1 200 OK
Content-Type: application/jwt
Date: Mon, 14 Nov 2016 21:35:42 GMT
Content-Length: 100

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJib2IifQ.-51G5JQmpJleARHp8rIljBczPFanWT93d_N_7LQGUXU

Example: web based flow with 'Accept: text/html'

Sets the jwt token as cookie and redirects to a web page.

curl -i -H 'Accept: text/html' --data "username=bob&password=secret" http://127.0.0.1:6789/login
HTTP/1.1 303 See Other
Location: /
Set-Cookie: jwt_token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJib2IifQ.-51G5JQmpJleARHp8rIljBczPFanWT93d_N_7LQGUXU; HttpOnly

The JWT Token

Depending on the provider, the token my look as follows:

{
  "sub": "smancke",
  "picture": "https://avatars2.githubusercontent.com/u/4291379?v=3",
  "name": "Sebastian Mancke",
  "email": "s.mancke@tarent.de",
  "origin": "github"
}

Provider Backends

Htpasswd

Authentication against htpasswd file. MD5, SHA1 and Bcrypt are supported. But we recommend to only use bcrypt for security reasons (e.g. htpasswd -B -C 15).

Parameters for the provider:

Parameter-Name	Description
file	Path to the password file

Example:

loginsrv -backend 'provider=htpasswd,file=users

Osiam

OSIAM is a secure identity management solution providing REST based services for authentication and authorization. It implements the multplie OAuth2 flows, as well as SCIM for managing the user data.

To start loginsrv against the default osiam configuration on the same machine, use the following example.

loginsrv --jwt-secret=jwtsecret --text-logging -backend 'provider=osiam,endpoint=http://localhost:8080,clientId=example-client,clientSecret=secret'

Then go to http://127.0.0.1:6789/login and login with admin/koala.

Simple

Simple is a demo provider for testing only. It holds a user/password table in memory.

Example

loginsrv -backend provider=simple,bob=secret

Oauth2

The Oauth Web Flow (aka 3-leged-Oauth flow) is also supported. Currently the following oauth Provider are supported:

• github

An Oauth Provider supports the following parameters:

Parameter-Name	Description
client_id	Oauth Client ID
client_secret	Oauth Client Secret
scope	Space separated scope List (optional)
redirect_uri	Alternative Redirect URI (optional)

When configuring the oauth parameters at your external oauth provider, a redirect uri has to be supplied. This redirect uri has to point to the path /login/<provider>. If not supplied, the oauth redirect uri is caclulated out of the current url. This should work in most cases and should even work if loginsrv is routed through a reverse proxy, if the headers X-Forwarded-Host and X-Forwarded-Proto are set correctly.

Github Startup Example

$ docker run -p 80:80 tarent/loginsrv -github client_id=xxx,client_secret=yyy

Templating

A custom template can be supplied by the paramter template. You can find the original template in login/login_form.go.

The templating uses the golang build in template language. A short intro can be found here.

When you specify a custom template, only the layout of the original template is replaced. The partials of the original are still loaded into the tempalte context and can be used by your template. So a minimal unstyled login template could look like this:

<!DOCTYPE html>
<html>
  <head>
      <!-- your styles -->
  <head>
  <body>
      <!-- your header -->

      {{ if .Error}}
        <div class="alert alert-danger" role="alert">
          <strong>Internal Error. </strong> Please try again later.
        </div>
      {{end}}

      {{if .Authenticated}}

         {{template "userInfo" . }}

      {{else}}

        {{template "login" . }}

      {{end}}

      <!-- your footer -->
</body>
</html>