traefik-forward-auth/README.md

# Traefik Forward Auth [![Build Status](https://travis-ci.org/thomseddon/traefik-forward-auth.svg?branch=master)](https://travis-ci.org/thomseddon/traefik-forward-auth) [![Go Report Card](https://goreportcard.com/badge/github.com/thomseddon/traefik-forward-auth)](https://goreportcard.com/report/github.com/thomseddon/traefik-forward-auth) ![Docker Pulls](https://img.shields.io/docker/pulls/thomseddon/traefik-forward-auth.svg) [![GitHub release](https://img.shields.io/github/release/thomseddon/traefik-forward-auth.svg)](https://GitHub.com/thomseddon/traefik-forward-auth/releases/)


A minimal forward authentication service that provides Google oauth based login and authentication for the [traefik](https://github.com/containous/traefik) reverse proxy/load balancer.

## Why?

- Seamlessly overlays any http service with a single endpoint (see: `url-path` in [Configuration](#configuration))
- Supports multiple domains/subdomains by dynamically generating redirect_uri's
- Allows authentication to be selectively applied/bypassed based on request parameters (see `rules` in [Configuration](#configuration)))
- Supports use of centralised authentication host/redirect_uri (see `auth-host` in [Configuration](#configuration)))
- Allows authentication to persist across multiple domains (see [Cookie Domains](#cookie-domains))
- Supports extended authentication beyond Google token lifetime (see: `lifetime` in [Configuration](#configuration))

# Contents

- [Releases](#releases)
- [Usage](#usage)
  - [Simple](#simple)
  - [Advanced](#advanced)
  - [OAuth Configuration](#oauth-configuration)
- [Configuration](#configuration)
  - [Overview](#overview)
  - [Option Details](#option-details)
- [Concepts](#concepts)
  - [Forwarded Headers](#forwarded-headers)
  - [User Restriction](#user-restriction)
  - [Operation Modes](#operation-modes)
    - [Overlay Mode](#overlay-mode)
    - [Auth Host Mode](#auth-host-mode)
- [Copyright](#copyright)
- [License](#license)

## Releases

We recommend using the `2` tag on docker hub.

You can also use the latest incremental releases found on [docker hub](https://hub.docker.com/r/thomseddon/traefik-forward-auth/tags) and [github](https://github.com/thomseddon/traefik-forward-auth/releases).

#### Upgrade Guide

v2 was released in June 2019, whilst this is fully backwards compatible, a number of configuration options were modified, please see the [upgrade guide](https://github.com/thomseddon/traefik-forward-auth/wiki/v2-Upgrade-Guide) to prevent warnings on startup and ensure you are using the current configuration.

## Usage

#### Simple:

See below for instructions on how to setup your [OAuth Configuration](#oauth-configuration).

docker-compose.yml:

```yaml
version: '3'

services:
  traefik:
    image: traefik:1.7
    ports:
      - "8085:80"
    volumes:
      - ./traefik.toml:/traefik.toml
      - /var/run/docker.sock:/var/run/docker.sock

  traefik-forward-auth:
    image: thomseddon/traefik-forward-auth:2
    environment:
      - CLIENT_ID=your-client-id
      - CLIENT_SECRET=your-client-secret
      - SECRET=something-random
      - INSECURE_COOKIE=true # Example assumes no https, do not use in production

  whoami:
    image: emilevauge/whoami:latest
    labels:
      - "traefik.frontend.rule=Host:whoami.mycompany.com"
```

traefik.toml:

```toml
[entryPoints]
    [entryPoints.http]
    address = ":80"

    [entryPoints.http.auth.forward]
    address = "http://traefik-forward-auth:4181"
    authResponseHeaders = ["X-Forwarded-User"]

[docker]
endpoint = "unix:///var/run/docker.sock"
network = "traefik"
```

#### Advanced:

Please see the examples directory for a more complete [docker-compose.yml](https://github.com/thomseddon/traefik-forward-auth/blob/master/examples/docker-compose.yml) and full [traefik.toml](https://github.com/thomseddon/traefik-forward-auth/blob/master/examples/traefik.toml).

Also in the examples directory is [docker-compose-auth-host.yml](https://github.com/thomseddon/traefik-forward-auth/blob/master/examples/docker-compose-auth-host.yml) which shows how to configure a central auth host, along with some other options.

#### OAuth Configuration

Head to https://console.developers.google.com and make sure you've switched to the correct email account.

Create a new project then search for and select "Credentials" in the search bar. Fill out the "OAuth Consent Screen" tab.

Click "Create Credentials" > "OAuth client ID". Select "Web Application", fill in the name of your app, skip "Authorized JavaScript origins" and fill "Authorized redirect URIs" with all the domains you will allow authentication from, appended with the `url-path` (e.g. https://app.test.com/_oauth)

## Configuration

### Overview

The following configuration options are supported:

```
Usage:
  traefik-forward-auth [OPTIONS]

Application Options:
  --log-level=[trace|debug|info|warn|error|fatal|panic] Log level (default: warn) [$LOG_LEVEL]
  --log-format=[text|json|pretty]                       Log format (default: text) [$LOG_FORMAT]
  --auth-host=                                          Single host to use when returning from 3rd party auth [$AUTH_HOST]
  --config=                                             Path to config file [$CONFIG]
  --cookie-domain=                                      Domain to set auth cookie on, can be set multiple times [$COOKIE_DOMAIN]
  --insecure-cookie                                     Use insecure cookies [$INSECURE_COOKIE]
  --cookie-name=                                        Cookie Name (default: _forward_auth) [$COOKIE_NAME]
  --csrf-cookie-name=                                   CSRF Cookie Name (default: _forward_auth_csrf) [$CSRF_COOKIE_NAME]
  --default-action=[auth|allow]                         Default action (default: auth) [$DEFAULT_ACTION]
  --domain=                                             Only allow given email domains, can be set multiple times [$DOMAIN]
  --lifetime=                                           Lifetime in seconds (default: 43200) [$LIFETIME]
  --url-path=                                           Callback URL Path (default: /_oauth) [$URL_PATH]
  --secret=                                             Secret used for signing (required) [$SECRET]
  --whitelist=                                          Only allow given email addresses, can be set multiple times [$WHITELIST]
  --rules.<name>.<param>=                               Rule definitions, param can be: "action" or "rule"

Google Provider:
  --providers.google.client-id=                         Client ID [$PROVIDERS_GOOGLE_CLIENT_ID]
  --providers.google.client-secret=                     Client Secret [$PROVIDERS_GOOGLE_CLIENT_SECRET]
  --providers.google.prompt=                            Space separated list of OpenID prompt options [$PROVIDERS_GOOGLE_PROMPT]

Help Options:
  -h, --help                                            Show this help message
```

All options can be supplied in any of the following ways, in the following precedence (first is highest precedence):

1. **Command Arguments/Flags** - As shown above
2. **Environment Variables** - As shown in square brackets above
3. **File**
    1. Use INI format (e.g. `url-path = _oauthpath`)
    2. Specify the file location via the `--config` flag or `$CONFIG` environment variable
    3. Can be specified multiple times, each file will be read in the order they are passed

### Option Details

- `auth-host`

  When set, when a user returns from authentication with a 3rd party provider they will always be forwarded to this host. By using one central host, this means you only need to add this `auth-host` as a valid redirect uri to your 3rd party provider.

  The host should be specified without protocol or path, for example:

   ```
   --auth-host="auth.example.com"
   ```

   For more details, please also read the [Auth Host Mode](#auth-host-mode), operation mode in the concepts section.

   Please Note - this should be considered advanced usage, if you are having problems please try disabling this option and then re-read the [Auth Host Mode](#auth-host-mode) section.

- `config`

   Used to specify the path to a configuration file, can be set multiple times, each file will be read in the order they are passed. Options should be set in an INI format, for example:

   ```
   url-path = _oauthpath
   ```

- `cookie-domain`

  When set, if a user successfully completes authentication, then if the host of the original request requiring authentication is a subdomain of a given cookie domain, then the authentication cookie will be set for the higher level cookie domain. This means that a cookie can allow access to multiple subdomains without re-authentication. Can be specificed multiple times.

   For example:
   ```
   --cookie-domain="example.com"  --cookie-domain="test.org"
   ```

   For example, if the cookie domain `test.com` has been set, and a request comes in on `app1.test.com`, following authentication the auth cookie will be set for the whole `test.com` domain. As such, if another request is forwarded for authentication from `app2.test.com`, the original cookie will be sent and so the request will be allowed without further authentication.

   Beware however, if using cookie domains whilst running multiple instances of traefik/traefik-forward-auth for the same domain, the cookies will clash. You can fix this by using a different `cookie-name` in each host/cluster or by using the same `cookie-secret` in both instances.

- `insecure-cookie`

   If you are not using HTTPS between the client and traefik, you will need to pass the `insecure-cookie` option which will mean the `Secure` attribute on the cookie will not be set.

- `cookie-name`

   Set the name of the cookie set following successful authentication.

   Default: `_forward_auth`

- `csrf-cookie-name`

   Set the name of the temporary CSRF cookie set during authentication.

   Default: `_forward_auth_csrf`

- `default-action`

   Specifies the behavior when a request does not match any [rules](#rules). Valid options are `auth` or `allow`.

   Default: `auth` (i.e. all requests require authentication)

- `domain`

   When set, only users matching a given domain will be permitted to access.

   For example, setting `--domain=example.com --domain=test.org` would mean that only users from example.com or test.org will be permitted. So thom@example.com would be allowed but thom@another.com would not.

   For more details, please also read [User Restriction](#user-restriction) in the concepts section.

- `lifetime`

   How long a successful authentication session should last, in seconds.

   Default: `43200` (12 hours)

- `url-path`

   Customise the path that this service uses to handle the callback following authentication.

   Default: `/_oauth`

   Please note that when using the default [Overlay Mode](#overlay-mode) requests to this exact path will be intercepted by this service and not forwarded to your application. Use this option (or [Auth Host Mode](#auth-host-mode)) if the default `/_oauth` path will collide with an existing route in your application.

- `secret`

   Used to sign cookies authentication, should be a random (e.g. `openssl rand -hex 16`)

- `whitelist`

   When set, only specified users will be permitted.

   For example, setting `--whitelist=thom@example.com --whitelist=alice@example.com` would mean that only those two exact users will be permitted. So thom@example.com would be allowed but john@example.com would not.

   For more details, please also read [User Restriction](#user-restriction) in the concepts section.

- `rules`

   Specify selective authentication rules. Rules are specified in the following format: `rule.<name>.<param>=<value>`

   - `<name>` can be any string and is only used to group rules together
   - `<param>` can be:
       - `action` - same usage as [`default-action`](#default-action), supported values:
           - `auth` (default)
           - `allow`
       - `rule` - a rule to match a request, this uses traefik's v2 rule parser for which you can find the documentation here: https://docs.traefik.io/v2.0/routing/routers/#rule, supported values are summarised here:
           - ``Headers(`key`, `value`)``
           - ``HeadersRegexp(`key`, `regexp`)``
           - ``Host(`example.com`, ...)``
           - ``HostRegexp(`example.com`, `{subdomain:[a-z]+}.example.com`, ...)``
           - ``Method(methods, ...)``
           - ``Path(`path`, `/articles/{category}/{id:[0-9]+}`, ...)``
           - ``PathPrefix(`/products/`, `/articles/{category}/{id:[0-9]+}`)``
           - ``Query(`foo=bar`, `bar=baz`)``

   For example:
   ```
   rule.1.action = allow
   rule.1.rule = PathPrefix(`/api/public`) && Headers(`Content-Type`, `application/json`)

   rule.two.action = allow
   rule.two.rule = Path(`/public`)
   ```

   In the above example, the first rule would allow requests that begin with `/api/public` and contain the `Content-Type` header with a value of `application/json`. It would also allow requests that had the exact path `/public`.

## Concepts

### User Restriction

You can restrict who can login with the following parameters:

* `domain` - Use this to limit logins to a specific domain, e.g. test.com only
* `whitelist` - Use this to only allow specific users to login e.g. thom@test.com only

Note, if you pass `whitelist` then only this is checked and `domain` is effectively ignored.

### Forwarded Headers

The authenticated user is set in the `X-Forwarded-User` header, to pass this on add this to the `authResponseHeaders` config option in traefik, as shown [here](https://github.com/thomseddon/traefik-forward-auth/blob/master/examples/docker-compose-dev.yml).

### Operation Modes

#### Overlay Mode

Overlay is the default operation mode, in this mode the authorisation endpoint is overlayed onto any domain. By default the `/_oauth` path is used, this can be customised using the `url-path` option.

The user flow will be:

1. Request to `www.myapp.com/home`
2. User redirected to Google login
3. After Google login, user is redirected to `www.myapp.com/_oauth`
4. Token, user and CSRF cookie is validated (this request in intercepted and is never passed to your application)
5. User is redirected to `www.myapp.com/home`
6. Request is allowed

As the hostname in the `redirect_uri` is dynamically generated based on the original request, every hostname must be permitted in the Google OAuth console (e.g. `www.myappp.com` would need to be added in the above example)

#### Auth Host Mode

This is an optional mode of operation that is useful when dealing with a large number of subdomains, it is activated by using the `auth-host` config option (see [this example docker-compose.yml](https://github.com/thomseddon/traefik-forward-auth/blob/master/examples/docker-compose-auth-host.yml)).

For example, if you have a few applications: `app1.test.com`, `app2.test.com`, `appN.test.com`, adding every domain to Google's console can become laborious.
To utilise an auth host, permit domain level cookies by setting the cookie domain to `test.com` then set the `auth-host` to: `auth.test.com`.

The user flow will then be:

1. Request to `app10.test.com/home/page`
2. User redirected to Google login
3. After Google login, user is redirected to `auth.test.com/_oauth`
4. Token, user and CSRF cookie is validated, auth cookie is set to `test.com`
5. User is redirected to `app10.test.com/home/page`
6. Request is allowed

With this setup, only `auth.test.com` must be permitted in the Google console.

Two criteria must be met for an `auth-host` to be used:

1. Request matches given `cookie-domain`
2. `auth-host` is also subdomain of same `cookie-domain`

Please note: For Auth Host mode to work, you must ensure that requests to your auth-host are routed to the traefik-forward-auth container, as demonstrated with the service labels in the [docker-compose-auth.yml](https://github.com/thomseddon/traefik-forward-auth/blob/master/examples/docker-compose-auth-host.yml) example.

## Copyright

2018 Thom Seddon

## License

[MIT](https://github.com/thomseddon/traefik-forward-auth/blob/master/LICENSE.md)