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
• caddyserver plugin

Supported Provider Backends

The following providers (login backends) are supported.

• Htpasswd
• OSIAM
• Simple (user/password pairs by configuration)
• Httpupstream
• Oauth2
  • Github Login
  • Google Login

Questions

For questions and support please use the Gitter chat room.

Configuration and Startup

Config Options

Note for Caddy users: Not all parameters are available in Caddy. See the table for details. With Caddy, the parameter names can be also be used with _ in the names, e.g. cookie_http_only.

Parameter	Type	Default	Caddy	Description
-cookie-domain	string		X	The optional domain parameter for the cookie
-cookie-expiry	string	session	X	The expiry duration for the cookie, e.g. 2h or 3h30m
-cookie-http-only	boolean	true	X	Set the cookie with the http only flag
-cookie-name	string	"jwt_token"	X	The name of the jwt cookie
-github	value		X	Oauth config in the form: client_id=..,client_secret=..[,scope=..,][redirect_uri=..]
-google	value		X	Oauth config in the form: client_id=..,client_secret=..[,scope=..,][redirect_uri=..]
-host	string	"localhost"	-	The host to listen on
-htpasswd	value		X	Htpasswd login backend opts: file=/path/to/pwdfile
-jwt-expiry	go duration	24h	X	The expiry duration for the jwt token, e.g. 2h or 3h30m
-jwt-secret	string	"random key"	X	The secret to sign the jwt token
-log-level	string	"info"	-	The log level
-login-path	string	"/login"	X	The path of the login resource
-logout-url	string		X	The url or path to redirect after logout
-osiam	value		X	OSIAM login backend opts: endpoint=..,client_id=..,client_secret=..
-port	string	"6789"	-	The port to listen on
-simple	value		X	Simple login backend opts: user1=password,user2=password,..
-success-url	string	"/"	X	The url to redirect after login
-template	string		X	An alternative template for the login form
-text-logging	boolean	true	-	Log in text format instead of json
-jwt-refreshes	int	0	X	The maximum amount of jwt refreshes.
-grace-period	go duration	5s	-	Duration to wait after SIGINT/SIGTERM for existing requests. No new requests are accepted.

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

$ docker run -d -p 8080:8080 tarent/loginsrv -jwt-secret my_secret -simple bob=secret

$ curl --data "username=bob&password=secret" 127.0.0.1:8080/login
eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJib2IifQ.uWoJkSXTLA_RvfLKe12pb4CyxQNxe5_Ovw-N5wfQwkzXz2enbhA9JZf8MmTp9n-TTDcWdY3Fd1SA72_M20G9lQ

The same configuration could be written with environment variables this way:

$ docker run -d -p 8080:8080 -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

Performs 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.

JWT-Refresh

If the POST-Parameters for username and password are missing and a valid JWT-Cookie is part of the request, then the JWT-Cookie is refreshed. This only happens if the jwt-refreshes config option is set to a value greater than 0.

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 can also be sent 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 may 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 -htpasswd file=users

Httpupstream

Authentication against an upstream http server by performing a http basic authenticated request and checking the response for a http 200 OK status code. Anything other than a 200 OK status code will result in a failure to authenticate.

Parameters for the provider:

Parameter-Name	Description
upstream	http/https url to call
skipverify	true to ignore TLS errors (optional, false by default)
timeout	request timeout (optional 1m by default, go duration syntax is supported)

Example:

loginsrv -httpupstream upstream=https://google.com,timeout=1s

OSIAM

OSIAM is a secure identity management solution providing REST based services for authentication and authorization. It implements the multiple 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 -osiam endpoint=http://localhost:8080,client_id=example-client,client_secret=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 -simple bob=secret

Oauth2

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

• github
• google

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 calculated 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 parameter 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 template 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>