oauth2_proxy

by bitly

A reverse proxy that provides authentication with Google, Github or other provider

5.0K Stars 1.2K Forks Last release: over 3 years ago (v2.2) MIT License 386 Commits 8 Releases

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oauth2_proxy

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

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NOTICE: This project was officially archived by Bitly at the end of September 2018. Bitly will no longer be accepting PRs or helping on issues. There has been a discussion to find a new home for the project which has led to the following notable forks:

  • pomerium an identity-access proxy, inspired by BeyondCorp.
  • buzzfeed/sso a "double OAuth2" flow, where sso-auth is the OAuth2 provider for sso-proxy and Google is the OAuth2 provider for sso-auth.
  • openshift/oauth_proxy an openshift specific version of this project.
  • pusher/oauth2_proxy official hard fork of this project.

Please submit all future PRs and issues to pusher/oauth2_proxy.

Architecture

OAuth2 Proxy Architecture

Installation

  1. Download Prebuilt Binary (current release is
    v2.2
    ) or build with
    $ go get github.com/bitly/oauth2_proxy
    which will put the binary in
    $GOROOT/bin
    Prebuilt binaries can be validated by extracting the file and verifying it against the
    sha256sum.txt
    checksum file provided for each release starting with version
    v2.3
    .
    sha256sum -c sha256sum.txt 2>&1 | grep OK
    oauth2_proxy-2.3.linux-amd64: OK
    
  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 :

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. Choose the new project from the top right project dropdown (only if another project is selected)
  3. In the project Dashboard center pane, choose "API Manager"
  4. In the left Nav pane, choose "Credentials"
  5. In the center pane, choose "OAuth consent screen" tab. Fill in "Product name shown to users" and hit save.
  6. In the center pane, choose "Credentials" tab.
    • Open the "New credentials" drop down
    • Choose "OAuth client ID"
    • Choose "Web application"
    • Application name is freeform, choose something appropriate
    • Authorized JavaScript origins is your domain ex:
      https://internal.yourcompany.com
    • Authorized redirect URIs is the location of oauth2/callback ex:
      https://internal.yourcompany.com/oauth2/callback
    • Choose "Create"
  7. 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.

Restrict auth to specific Google groups on your domain. (optional)

  1. Create a service account: https://developers.google.com/identity/protocols/OAuth2ServiceAccount and make sure to download the json file.
  2. Make note of the Client ID for a future step.
  3. Under "APIs & Auth", choose APIs.
  4. Click on Admin SDK and then Enable API.
  5. Follow the steps on https://developers.google.com/admin-sdk/directory/v1/guides/delegation#delegatedomain-wideauthoritytoyourserviceaccount and give the client id from step 2 the following oauth scopes:
    https://www.googleapis.com/auth/admin.directory.group.readonly
    https://www.googleapis.com/auth/admin.directory.user.readonly
    
  6. Follow the steps on https://support.google.com/a/answer/60757 to enable Admin API access.
  7. Create or choose an existing administrative email address on the Gmail domain to assign to the
    google-admin-email
    flag. This email will be impersonated by this client to make calls to the Admin SDK. See the note on the link from step 5 for the reason why.
  8. Create or choose an existing email group and set that email to the
    google-group
    flag. You can pass multiple instances of this flag with different groups and the user will be checked against all the provided groups.
  9. Lock down the permissions on the json file downloaded from step 1 so only oauth2_proxy is able to read the file and set the path to the file in the
    google-service-account-json
    flag.
  10. Restart oauth2_proxy.

Note: The user is checked against the group members list on initial authentication and every time the token is refreshed ( about once an hour ).

Azure Auth Provider

  1. Add an application to your Azure Active Directory tenant.
  2. On the App properties page provide the correct Sign-On URL ie
    https://internal.yourcompany.com/oauth2/callback
  3. If applicable take note of your
    TenantID
    and provide it via the
    --azure-tenant=
    commandline option. Default the
    common
    tenant is used.

The Azure AD auth provider uses

openid
as it default scope. It uses
https://graph.windows.net
as a default protected resource. It call to
https://graph.windows.net/me
to get the email address of the user that logs in.

Facebook Auth Provider

  1. Create a new FB App from https://developers.facebook.com/
  2. Under FB Login, set your Valid OAuth redirect URIs to
    https://internal.yourcompany.com/oauth2/callback

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 any of these teams (slug), separated by a comma

If you are using GitHub enterprise, make sure you set the following to the appropriate url:

-login-url="http(s):///login/oauth/authorize"
-redeem-url="http(s):///login/oauth/access_token"
-validate-url="http(s):///api/v3"

GitLab Auth Provider

Whether you are using GitLab.com or self-hosting GitLab, follow these steps to add an application

If you are using self-hosted GitLab, make sure you set the following to the appropriate URL:

-login-url="/oauth/authorize"
-redeem-url="/oauth/token"
-validate-url="/api/v4/user"

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 rbasicprofile and remailaddress.
    • 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

Microsoft Azure AD Provider

For adding an application to the Microsoft Azure AD follow these steps to add an application.

Take note of your

TenantId
if applicable for your situation. The
TenantId
can be used to override the default
common
authorization server with a tenant specific server.

OpenID Connect Provider

OpenID Connect is a spec for OAUTH 2.0 + identity that is implemented by many major providers and several open source projects. This provider was originally built against CoreOS Dex and we will use it as an example.

  1. Launch a Dex instance using the getting started guide.
  2. Setup oauth2_proxy with the correct provider and using the default ports and callbacks.
  3. Login with the fixture use in the dex guide and run the oauth2_proxy with the following args:

    -provider oidc -client-id oauth2_proxy -client-secret proxy -redirect-url http://127.0.0.1:4180/oauth2/callback -oidc-issuer-url http://127.0.0.1:5556 -cookie-secure=false -email-domain example.com

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 addresses use
--email-domain=*
.

Configuration

oauth2_proxy
can be configured via config file, command line options or environment variables.

To generate a strong cookie secret use

python -c 'import os,base64; print base64.urlsafe_b64encode(os.urandom(16))'

Config File

An example oauth2_proxy.cfg 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 string: OAuth approval_prompt (default "force")
  -authenticated-emails-file string: authenticate against emails via file (one per line)
  -azure-tenant string: go to a tenant-specific or common (tenant-independent) endpoint. (default "common")
  -basic-auth-password string: the password to set when passing the HTTP Basic Auth header
  -client-id string: the OAuth Client ID: ie: "123456.apps.googleusercontent.com"
  -client-secret string: the OAuth Client Secret
  -config string: path to config file
  -cookie-domain string: an optional cookie domain to force cookies to (ie: .yourcompany.com)
  -cookie-expire duration: expire timeframe for cookie (default 168h0m0s)
  -cookie-httponly: set HttpOnly cookie flag (default true)
  -cookie-name string: the name of the cookie that the oauth_proxy creates (default "_oauth2_proxy")
  -cookie-refresh duration: refresh the cookie after this duration; 0 to disable
  -cookie-secret string: the seed string for secure cookies (optionally base64 encoded)
  -cookie-secure: set secure (HTTPS) cookie flag (default true)
  -custom-templates-dir string: path to custom html templates
  -display-htpasswd-form: display username / password login form if an htpasswd file is provided (default true)
  -email-domain value: authenticate emails with the specified domain (may be given multiple times). Use * to authenticate any email
  -footer string: custom footer string. Use "-" to disable default footer.
  -github-org string: restrict logins to members of this organisation
  -github-team string: restrict logins to members of any of these teams (slug), separated by a comma
  -google-admin-email string: the google admin to impersonate for api calls
  -google-group value: restrict logins to members of this google group (may be given multiple times).
  -google-service-account-json string: the path to the service account json credentials
  -htpasswd-file string: additionally authenticate against a htpasswd file. Entries must be created with "htpasswd -s" for SHA encryption
  -http-address string: [http://]: or unix:// to listen on for HTTP clients (default "127.0.0.1:4180")
  -https-address string: : to listen on for HTTPS clients (default ":443")
  -login-url string: Authentication endpoint
  -pass-access-token: pass OAuth access_token to upstream via X-Forwarded-Access-Token header
  -pass-basic-auth: pass HTTP Basic Auth, X-Forwarded-User and X-Forwarded-Email information to upstream (default true)
  -pass-host-header: pass the request Host Header to upstream (default true)
  -pass-user-headers: pass X-Forwarded-User and X-Forwarded-Email information to upstream (default true)
  -profile-url string: Profile access endpoint
  -provider string: OAuth provider (default "google")
  -proxy-prefix string: the url root path that this proxy should be nested under (e.g. //sign_in) (default "/oauth2")
  -redeem-url string: Token redemption endpoint
  -redirect-url string: the OAuth Redirect URL. ie: "https://internalapp.yourcompany.com/oauth2/callback"
  -request-logging: Log requests to stdout (default true)
  -request-logging-format: Template for request log lines (see "Logging Format" paragraph below)
  -resource string: The resource that is protected (Azure AD only)
  -scope string: OAuth scope specification
  -set-xauthrequest: set X-Auth-Request-User and X-Auth-Request-Email response headers (useful in Nginx auth_request mode)
  -signature-key string: GAP-Signature request signature key (algorithm:secretkey)
  -skip-auth-preflight: will skip authentication for OPTIONS requests
  -skip-auth-regex value: bypass authentication for requests path's that match (may be given multiple times)
  -skip-provider-button: will skip sign-in-page to directly reach the next step: oauth/start
  -ssl-insecure-skip-verify: skip validation of certificates presented when using HTTPS
  -tls-cert string: path to certificate file
  -tls-key string: path to private key file
  -upstream value: the http url(s) of the upstream endpoint or file:// paths for static files. Routing is based on the path
  -validate-url string: Access token validation endpoint
  -version: print version string

See below for provider specific options

Upstreams Configuration

oauth2_proxy
supports having multiple upstreams, and has the option to pass requests on to HTTP(S) servers or serve static files from the file system. HTTP and HTTPS upstreams are configured by providing a URL such as
http://127.0.0.1:8080/
for the upstream parameter, that will forward all authenticated requests to be forwarded to the upstream server. If you instead provide
http://127.0.0.1:8080/some/path/
then it will only be requests that start with
/some/path/
which are forwarded to the upstream.

Static file paths are configured as a file:// URL.

file:///var/www/static/
will serve the files from that directory at
http://[oauth2_proxy url]/var/www/static/
, which may not be what you want. You can provide the path to where the files should be available by adding a fragment to the configured URL. The value of the fragment will then be used to specify which path the files are available at.
file:///var/www/static/#/static/
will ie. make
/var/www/static/
available at
http://[oauth2_proxy url]/static/
.

Multiple upstreams can either be configured by supplying a comma separated list to the

-upstream
parameter, supplying the parameter multiple times or provinding a list in the config file. When multiple upstreams are used routing to them will be based on the path they are set up with.

Environment variables

The following environment variables can be used in place of the corresponding command-line arguments:

  • OAUTH2_PROXY_CLIENT_ID
  • OAUTH2_PROXY_CLIENT_SECRET
  • OAUTH2_PROXY_COOKIE_NAME
  • OAUTH2_PROXY_COOKIE_SECRET
  • OAUTH2_PROXY_COOKIE_DOMAIN
  • OAUTH2_PROXY_COOKIE_EXPIRE
  • OAUTH2_PROXY_COOKIE_REFRESH
  • OAUTH2_PROXY_SIGNATURE_KEY

SSL Configuration

There are two recommended configurations.

1) Configure SSL Termination 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:
./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 (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:
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:
./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 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.
  • /oauth2/auth - only returns a 202 Accepted response or a 401 Unauthorized response; for use with the Nginx
    auth_request
    directive

Request signatures

If

signature_key
is defined, proxied requests will be signed with the
GAP-Signature
header, which is a Hash-based Message Authentication Code (HMAC) of selected request information and the request body see
SIGNATURE_HEADERS
in
oauthproxy.go
.

signature_key
must be of the form
algorithm:secretkey
, (ie:
signature_key = "sha1:secret0"
)

For more information about HMAC request signature validation, read the following:

Logging Format

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

 -  [19/Mar/2015:17:20:19 -0400]  GET  "/path/" HTTP/1.1 ""   

If you require a different format than that, you can configure it with the

-request-logging-format
flag. The default format is configured as follows:
{{.Client}} - {{.Username}} [{{.Timestamp}}] {{.Host}} {{.RequestMethod}} {{.Upstream}} {{.RequestURI}} {{.Protocol}} {{.UserAgent}} {{.StatusCode}} {{.ResponseSize}} {{.RequestDuration}}

See

logMessageData
in
logging_handler.go
for all available variables.

Adding a new Provider

Follow the examples in the

providers
package to define a new

Provider
instance. Add a new
case
to
providers.New()
to allow
oauth2_proxy
to use the new
Provider
.

Configuring for use with the Nginx
auth_request
directive

The Nginx

auth_request
directive allows Nginx to authenticate requests via the oauth2_proxy's

/auth
endpoint, which only returns a 202 Accepted response or a 401 Unauthorized response without proxying the request through. For example:
server {
  listen 443 ssl;
  server_name ...;
  include ssl/ssl.conf;

location /oauth2/ { 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_set_header X-Auth-Request-Redirect $request_uri; } location = /oauth2/auth { 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; # nginx auth_request includes headers but not body proxy_set_header Content-Length ""; proxy_pass_request_body off; }

location / { auth_request /oauth2/auth; error_page 401 = /oauth2/sign_in;

# pass information via X-User and X-Email headers to backend,
# requires running with --set-xauthrequest flag
auth_request_set $user   $upstream_http_x_auth_request_user;
auth_request_set $email  $upstream_http_x_auth_request_email;
proxy_set_header X-User  $user;
proxy_set_header X-Email $email;

# if you enabled --cookie-refresh, this is needed for it to work with auth_request
auth_request_set $auth_cookie $upstream_http_set_cookie;
add_header Set-Cookie $auth_cookie;

proxy_pass http://backend/;
# or "root /path/to/site;" or "fastcgi_pass ..." etc

} }

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