JWT login microservice with plugable backends such as OAuth2, Google, Github, htpasswd, osiam, ..
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README.md

loginsrv

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

Docker Build Status Go Report Card Coverage Status Join the chat at https://gitter.im/tarent/loginsrv

** Attention: Update to v1.3.0 for Google Login Update !!!! **

Google will stop support for the Google+ APIs. So we changed loginsrv to use the standard oauth endpoints for Google login. Please update loginsrv to v1.3.0 if you are using google login.

** Attention: Since v1.3.0, pure HTTP is not supported by default **

Since v1.3.0, loginsrv sets the secure flag for the login cookie. So, if you use HTTP fo connect with the browser, e.g. for testing, you browser will ignore the cookie. Use the flag -cookie-secure=false when testing without HTTPS.

Abstract

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

  • Standalone microservice
  • Docker container
  • Golang library
  • Caddy plugin. (See caddy/README.md for details)

Supported Provider Backends

The following providers (login backends) are supported.

Questions

For questions and support please use the Gitter chat room.

Join the chat at https://gitter.im/tarent/loginsrv

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 Optional domain parameter for the cookie
-cookie-expiry string session X 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 Name of the JWT cookie
-cookie-secure boolean true X Set the secure flag on the JWT cookie. (Set this to false for plain HTTP support)
-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=..]
-bitbucket value X OAuth config in the form: client_id=..,client_secret=..[,scope=..][,redirect_uri=..]
-facebook value X OAuth config in the form: client_id=..,client_secret=..[,scope=..][,redirect_uri=..]
-gitlab value X OAuth config in the form: client_id=..,client_secret=..[,scope=..,][redirect_uri=..]
-host string "localhost" - Host to listen on
-htpasswd value X Htpasswd login backend opts: file=/path/to/pwdfile
-jwt-expiry go duration 24h X Expiry duration for the JWT token, e.g. 2h or 3h30m
-jwt-secret string "random key" X Secret used to sign the JWT token. (See caddy/README.md for details.)
-jwt-algo string "HS512" X Signing algorithm to use (ES256, ES384, ES512, HS512, HS256, HS384, HS512)
-log-level string "info" - Log level
-login-path string "/login" X Path of the login resource
-logout-url string X URL or path to redirect to after logout
-osiam value X OSIAM login backend opts: endpoint=..,client_id=..,client_secret=..
-port string "6789" - Port to listen on
-redirect boolean true X Allow dynamic overwriting of the the success by query parameter
-redirect-query-parameter string "backTo" X URL parameter for the redirect target
-redirect-check-referer boolean true X Check the referer header to ensure it matches the host header on dynamic redirects
-redirect-host-file string "" X A file containing a list of domains that redirects are allowed to, one domain per line
-simple value X Simple login backend opts: user1=password,user2=password,..
-success-url string "/" X URL to redirect to after login
-prevent-external-redirects boolean true X Prevent dynamic redirects to external domains
-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 number of JWT refreshes
-grace-period go duration 5s - Duration to wait after SIGINT/SIGTERM for existing requests. No new requests are accepted.
-user-file string X A YAML file with user specific data for the tokens. (see below for an example)

Environment Variables

All of the above Config Options can also be applied as environment variables by using variables named this 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 -secure-cookie=false -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 SECURE_COOKIE=false -e LOGINSRV_JWT_SECRET=my_secret -e LOGINSRV_BACKEND=provider=simple,bob=secret tarent/loginsrv

API

GET /login

Per default, it returns a simple bootstrap styled login form for unauthenticated requests an a small page with user info authenticated requests. When the call accepts a JSON output, the json content of the token is returned authenticated requests.

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.

Parameter-Type Parameter Description
Http-Header Accept: text/html Return the login form or user html. default
Http-Header Accept: application/json Return the user Object as json, or 403 if not authenticated.

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 as a cookie named 'jwt_token' default
Http-Header Accept: application/jwt Returns the JWT 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
Get or Post backTo Dynamic redirect target after login (see (Redirects)[#redirects]) -success-url

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 Basic 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 as a 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

Example: AJAX call with JQuery to fetch a JWT token and create a cookie from it

Creates a cookie from a successful API call to login.

$.ajax({
	url: "http://localhost:8080/login",
	type: 'POST',
	dataType: 'text',
	contentType: 'application/json',
	data: JSON.stringify( { 
		'username': 'demo', 
		'password': 'demo'
	}),
	success: function(data) {
		document.cookie = "jwt_token=" + data + ";path=/";
	},
	error: function (xhr, ajaxOptions, thrownError) {
	}
});

Make sure your main page has JQuery:

<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>

Redirects

The API has support for a redirect query parameter, e.g. ?backTo=/dynamic/return/path. For security reasons, the default behaviour is very restrictive:

  • Only local redirects (same host) are allowed.
  • The Referer header is checked to ensure that the call to the login page came from the same page.

These restrictions are there, to prevent you from unchecked redirect attacks, e.g. phishing or login attacks. If you know, what you are doing, you can disable the Referer check with --redirect-check-referer=false and provide a whitelist file for allowed external domains with --redirect-host-file=/some/domains.txt.

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 authentication 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-legged-OAuth flow) is also supported. Currently the following OAuth provider is supported:

  • GitHub
  • Google
  • Bitbucket
  • Facebook
  • Gitlab

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>

User File

To customize the content of the JWT token, a YAML file with user data can be provided. After successful authentication against a backend system, the user is searched within the file and the content of the claims parameter is used to enhance the user JWT claim parameters.

To match an entry, the user file is searched in linear order and all attributes has to match the data of the authentication backend. The first matching entry will be used and all parameters below the claim attribute are written into the token. The following attributes can be used for matching:

  • sub - the username (all backends)
  • origin - the provider or backend name (all backends)
  • email - the mail address (the OAuth provider)
  • domain - the domain (Google only)
  • groups - the full path string of user groups enclosed in an array (Gitlab only)

Example:

  • The user bob will become the "role": "superAdmin", when authenticating with htpasswd file
  • The user admin@example.org will become "role": "admin" and "projects": ["example"], when authenticating with Google OAuth
  • All other Google users with the domain example will become "role": "user" and "projects": ["example"]
  • All other Gitlab users with group example/subgroup and othergroup will become "role": "admin".
  • All others will become "role": "unknown", indenpendent of the authentication provider
- sub: bob
  origin: htpasswd
  claims:
    role: superAdmin

- email: admin@example.org
  origin: Google
  claims:
    role: admin
    projects:
      - example

- domain: example.org
  origin: Google
  claims:
    role: user
    projects:
      - example

- groups:
    - example/subgroup
    - othergroup
  origin: gitlab
  claims:
    role: admin

- claims:
    role: unknown