oauth2_proxy/README.md

oauth2_proxy
=================

<small>(This project was renamed from Google Auth Proxy - May 2015)</small>

A reverse proxy that provides authentication using Providers (Google, Github, and others)
to validate accounts by email, domain or group.

[![Build Status](https://secure.travis-ci.org/bitly/oauth2_proxy.png?branch=master)](http://travis-ci.org/bitly/oauth2_proxy)


![Sign In Page](https://cloud.githubusercontent.com/assets/45028/4970624/7feb7dd8-6886-11e4-93e0-c9904af44ea8.png)

## Architecture

![OAuth2 Proxy Architecture](https://cloud.githubusercontent.com/assets/45028/8027702/bd040b7a-0d6a-11e5-85b9-f8d953d04f39.png)

## Installation

1. Download [Prebuilt Binary](https://github.com/bitly/oauth2_proxy/releases) (current release is `v2.0.1`) or build with `$ go get github.com/bitly/oauth2_proxy` which will put the binary in `$GOROOT/bin`
2. Select a Provider and Register an OAuth Application with a Provider
3. Configure OAuth2 Proxy using config file, command line options, or environment variables
4. Configure SSL or Deploy behind a SSL endpoint (example provided for Nginx)

## OAuth Provider Configuration

You will need to register an OAuth application with a Provider (Google, Github or another provider), and configure it with Redirect URI(s) for the domain you intend to run `oauth2_proxy` on.

Valid providers are :

* [Google](#google-auth-provider) *default*
* [GitHub](#github-auth-provider)
* [LinkedIn](#linkedin-auth-provider)
* [MyUSA](#myusa-auth-provider)

The provider can be selected using the `provider` configuration value.

### Google Auth Provider

For Google, the registration steps are:

1. Create a new project: https://console.developers.google.com/project
2. Under "APIs & Auth", choose "Credentials"
3. Now, choose "Create new Client ID"
   * The Application Type should be **Web application**
   * Enter your domain in the Authorized Javascript Origins `https://internal.yourcompany.com`
   * Enter the correct Authorized Redirect URL `https://internal.yourcompany.com/oauth2/callback`
     * NOTE: `oauth2_proxy` will _only_ callback on the path `/oauth2/callback`
4. Under "APIs & Auth" choose "Consent Screen"
   * Fill in the necessary fields and Save (this is _required_)
5. Take note of the **Client ID** and **Client Secret**

It's recommended to refresh sessions on a short interval (1h) with `cookie-refresh` setting which validates that the account is still authorized.

### GitHub Auth Provider

1. Create a new project: https://github.com/settings/developers
2. Under `Authorization callback URL` enter the correct url ie `https://internal.yourcompany.com/oauth2/callback`

The GitHub auth provider supports two additional parameters to restrict authentication to Organization or Team level access. Restricting by org and team is normally accompanied with `--email-domain=*`

    -github-org="": restrict logins to members of this organisation
    -github-team="": restrict logins to members of this team


### LinkedIn Auth Provider

For LinkedIn, the registration steps are:

1. Create a new project: https://www.linkedin.com/secure/developer
2. In the OAuth User Agreement section:
   * In default scope, select r_basicprofile and r_emailaddress.
   * In "OAuth 2.0 Redirect URLs", enter `https://internal.yourcompany.com/oauth2/callback`
3. Fill in the remaining required fields and Save.
4. Take note of the **Consumer Key / API Key** and **Consumer Secret / Secret Key**

### MyUSA Auth Provider

The [MyUSA](https://alpha.my.usa.gov) authentication service ([GitHub](https://github.com/18F/myusa))

## Email Authentication

To authorize by email domain use `--email-domain=yourcompany.com`. To authorize individual email addresses use `--authenticated-emails-file=/path/to/file` with one email per line. To authorize all email addresse use `--email-domain=*`.

## Configuration

`oauth2_proxy` can be configured via [config file](#config-file), [command line options](#command-line-options) or [environment variables](#environment-variables).

### Config File

An example [oauth2_proxy.cfg](contrib/oauth2_proxy.cfg.example) config file is in the contrib directory. It can be used by specifying `-config=/etc/oauth2_proxy.cfg`

### Command Line Options

```
Usage of oauth2_proxy:
  -approval_prompt="force": Oauth approval_prompt
  -authenticated-emails-file="": authenticate against emails via file (one per line)
  -client-id="": the OAuth Client ID: ie: "123456.apps.googleusercontent.com"
  -client-secret="": the OAuth Client Secret
  -config="": path to config file
  -cookie-domain="": an optional cookie domain to force cookies to (ie: .yourcompany.com)*
  -cookie-expire=168h0m0s: expire timeframe for cookie
  -cookie-httponly=true: set HttpOnly cookie flag
  -cookie-key="_oauth2_proxy": the name of the cookie that the oauth_proxy creates
  -cookie-refresh=0: refresh the cookie after this duration; 0 to disable
  -cookie-secret="": the seed string for secure cookies
  -cookie-secure=true: set secure (HTTPS) cookie flag
  -custom-templates-dir="": path to custom html templates
  -display-htpasswd-form=true: display username / password login form if an htpasswd file is provided
  -email-domain=: authenticate emails with the specified domain (may be given multiple times). Use * to authenticate any email
  -github-org="": restrict logins to members of this organisation
  -github-team="": restrict logins to members of this team
  -htpasswd-file="": additionally authenticate against a htpasswd file. Entries must be created with "htpasswd -s" for SHA encryption
  -http-address="127.0.0.1:4180": [http://]<addr>:<port> or unix://<path> to listen on for HTTP clients
  -https-address=":443": <addr>:<port> to listen on for HTTPS clients
  -login-url="": Authentication endpoint
  -pass-access-token=false: pass OAuth access_token to upstream via X-Forwarded-Access-Token header
  -pass-basic-auth=true: pass HTTP Basic Auth, X-Forwarded-User and X-Forwarded-Email information to upstream
  -basic-auth-password="": the password to set when passing the HTTP Basic Auth header
  -pass-host-header=true: pass the request Host Header to upstream
  -profile-url="": Profile access endpoint
  -provider="google": OAuth provider
  -proxy-prefix="/oauth2": the url root path that this proxy should be nested under (e.g. /<oauth2>/sign_in)
  -redeem-url="": Token redemption endpoint
  -redirect-url="": the OAuth Redirect URL. ie: "https://internalapp.yourcompany.com/oauth2/callback"
  -request-logging=true: Log requests to stdout
  -scope="": Oauth scope specification
  -skip-auth-regex=: bypass authentication for requests path's that match (may be given multiple times)
  -tls-cert="": path to certificate file
  -tls-key="": path to private key file
  -upstream=: the http url(s) of the upstream endpoint. If multiple, routing is based on path
  -validate-url="": Access token validation endpoint
  -version=false: print version string
```

See below for provider specific options

### Environment variables

The environment variables `OAUTH2_PROXY_CLIENT_ID`, `OAUTH2_PROXY_CLIENT_SECRET`, `OAUTH2_PROXY_COOKIE_SECRET`, `OAUTH2_PROXY_COOKIE_DOMAIN` and `OAUTH2_PROXY_COOKIE_EXPIRE` can be used in place of the corresponding command-line arguments.

## SSL Configuration

There are two recommended configurations. 

1) Configure SSL Terminiation with OAuth2 Proxy by providing a `--tls-cert=/path/to/cert.pem` and `--tls-key=/path/to/cert.key`.

The command line to run `oauth2_proxy` in this configuration would look like this:

```bash
./oauth2_proxy \
   --email-domain="yourcompany.com"  \
   --upstream=http://127.0.0.1:8080/ \
   --tls-cert=/path/to/cert.pem \
   --tls-key=/path/to/cert.key \
   --cookie-secret=... \
   --cookie-secure=true \
   --provider=... \
   --client-id=... \
   --client-secret=...
```


2) Configure SSL Termination with [Nginx](http://nginx.org/) (example config below), Amazon ELB, Google Cloud Platform Load Balancing, or ....

Because `oauth2_proxy` listens on `127.0.0.1:4180` by default, to listen on all interfaces (needed when using an
external load balancer like Amazon ELB or Google Platform Load Balancing) use `--http-address="0.0.0.0:4180"` or
`--http-address="http://:4180"`.

Nginx will listen on port `443` and handle SSL connections while proxying to `oauth2_proxy` on port `4180`.
`oauth2_proxy` will then authenticate requests for an upstream application. The external endpoint for this example
would be `https://internal.yourcompany.com/`.

An example Nginx config follows. Note the use of `Strict-Transport-Security` header to pin requests to SSL 
via [HSTS](http://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security):

```
server {
    listen 443 default ssl;
    server_name internal.yourcompany.com;
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/cert.key;
    add_header Strict-Transport-Security max-age=2592000;

    location / {
        proxy_pass http://127.0.0.1:4180;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Scheme $scheme;
        proxy_connect_timeout 1;
        proxy_send_timeout 30;
        proxy_read_timeout 30;
    }
}
```

The command line to run `oauth2_proxy` in this configuration would look like this:

```bash
./oauth2_proxy \
   --email-domain="yourcompany.com"  \
   --upstream=http://127.0.0.1:8080/ \
   --cookie-secret=... \
   --cookie-secure=true \
   --provider=... \
   --client-id=... \
   --client-secret=...
```


## Endpoint Documentation

OAuth2 Proxy responds directly to the following endpoints. All other endpoints will be proxied upstream when authenticated. The `/oauth2` prefix can be changed with the `--proxy-prefix` config variable.

* /robots.txt - returns a 200 OK response that disallows all User-agents from all paths; see [robotstxt.org](http://www.robotstxt.org/) for more info
* /ping - returns an 200 OK response
* /oauth2/sign_in - the login page, which also doubles as a sign out page (it clears cookies)
* /oauth2/start - a URL that will redirect to start the OAuth cycle
* /oauth2/callback - the URL used at the end of the OAuth cycle. The oauth app will be configured with this as the callback url.

## Logging Format

OAuth2 Proxy logs requests to stdout in a format similar to Apache Combined Log.

```
<REMOTE_ADDRESS> - <user@domain.com> [19/Mar/2015:17:20:19 -0400] <HOST_HEADER> GET <UPSTREAM_HOST> "/path/" HTTP/1.1 "<USER_AGENT>" <RESPONSE_CODE> <RESPONSE_BYTES> <REQUEST_DURATION>
```


## Adding a new Provider

Follow the examples in the [`providers` package](providers/) to define a new
`Provider` instance. Add a new `case` to
[`providers.New()`](providers/providers.go) to allow `oauth2_proxy` to use the
new `Provider`.