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Forward auth

Using forward auth uses your existing reverse proxy to do the proxying, and only uses the authentik outpost to check authentication and authorization.

To use forward auth instead of proxying, you have to change a couple of settings. In the Proxy Provider, make sure to use one of the Forward auth modes.

Single application​

Single application mode works for a single application hosted on its dedicated subdomain. This has the advantage that you can still do per-application access policies in authentik.

Domain level​

To use forward auth instead of proxying, you have to change a couple of settings. In the Proxy Provider, make sure to use the Forward auth (domain level) mode.

This mode differs from the Forward auth (single application) mode in the following points:

  • You don't have to configure an application in authentik for each domain
  • Users don't have to authorize multiple times

There are however also some downsides, mainly the fact that you can't restrict individual applications to different users.

The only configuration difference between single application and domain level is the host you specify.

For single application, you'd use the domain which the application is running on, and only /outpost.goauthentik.io is redirected to the outpost.

For domain level, you'd use the same domain as authentik.

info

example-outpost is used as a placeholder for the outpost name. authentik.company is used as a placeholder for the authentik install. app.company is used as a placeholder for the external domain for the application. outpost.company is used as a placeholder for the outpost. When using the embedded outpost, this can be the same as authentik.company

Nginx​

server {
    # SSL and VHost configuration
    listen                  443 ssl http2;
    server_name             _;

    ssl_certificate         /etc/ssl/certs/ssl-cert-snakeoil.pem;
    ssl_certificate_key     /etc/ssl/private/ssl-cert-snakeoil.key;

    # Increase buffer size for large headers
    # This is needed only if you get 'upstream sent too big header while reading response
    # header from upstream' error when trying to access an application protected by goauthentik
    proxy_buffers 8 16k;
    proxy_buffer_size 32k;

    location / {
        # Put your proxy_pass to your application here, and all the other statements you'll need
        # proxy_pass http://localhost:5000;
        # proxy_set_header Host $host;
        # proxy_set_header ...

        ##############################
        # authentik-specific config
        ##############################
        auth_request     /outpost.goauthentik.io/auth/nginx;
        error_page       401 = @goauthentik_proxy_signin;
        auth_request_set $auth_cookie $upstream_http_set_cookie;
        add_header       Set-Cookie $auth_cookie;

        # translate headers from the outposts back to the actual upstream
        auth_request_set $authentik_username $upstream_http_x_authentik_username;
        auth_request_set $authentik_groups $upstream_http_x_authentik_groups;
        auth_request_set $authentik_email $upstream_http_x_authentik_email;
        auth_request_set $authentik_name $upstream_http_x_authentik_name;
        auth_request_set $authentik_uid $upstream_http_x_authentik_uid;

        proxy_set_header X-authentik-username $authentik_username;
        proxy_set_header X-authentik-groups $authentik_groups;
        proxy_set_header X-authentik-email $authentik_email;
        proxy_set_header X-authentik-name $authentik_name;
        proxy_set_header X-authentik-uid $authentik_uid;
    }

    # all requests to /outpost.goauthentik.io must be accessible without authentication
    location /outpost.goauthentik.io {
        proxy_pass              http://outpost.company:9000/outpost.goauthentik.io;
        # ensure the host of this vserver matches your external URL you've configured
        # in authentik
        proxy_set_header        Host $host;
        proxy_set_header        X-Original-URL $scheme://$http_host$request_uri;
        add_header              Set-Cookie $auth_cookie;
        auth_request_set        $auth_cookie $upstream_http_set_cookie;
        proxy_pass_request_body off;
        proxy_set_header        Content-Length "";
    }

    # Special location for when the /auth endpoint returns a 401,
    # redirect to the /start URL which initiates SSO
    location @goauthentik_proxy_signin {
        internal;
        add_header Set-Cookie $auth_cookie;
        return 302 /outpost.goauthentik.io/start?rd=$request_uri;
        # For domain level, use the below error_page to redirect to your authentik server with the full redirect path
        # return 302 https://authentik.company/outpost.goauthentik.io/start?rd=$scheme://$http_host$request_uri;
    }
}

Traefik​

http:
    middlewares:
        authentik:
            forwardAuth:
                address: http://outpost.company:9000/outpost.goauthentik.io/auth/traefik
                trustForwardHeader: true
                authResponseHeaders:
                    - X-authentik-username
                    - X-authentik-groups
                    - X-authentik-email
                    - X-authentik-name
                    - X-authentik-uid
                    - X-authentik-jwt
                    - X-authentik-meta-jwks
                    - X-authentik-meta-outpost
                    - X-authentik-meta-provider
                    - X-authentik-meta-app
                    - X-authentik-meta-version
    routers:
        default-router:
            rule: "Host(`app.company`)"
            middlewares:
                - name: authentik
            priority: 10
            services: # Unchanged
        default-router-auth:
            match: "Host(`app.company`) && PathPrefix(`/outpost.goauthentik.io/`)"
            priority: 15
            services: http://outpost.company:9000/outpost.goauthentik.io

Enovy (Istio)​

info

Requires authentik 2022.6

info

Support for this is still in preview, please report bugs on GitHub.

Set the following settings on the IstioOperator resource:

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
    name: istio
    namespace: istio-system
spec:
    meshConfig:
        extensionProviders:
            - name: "authentik"
              envoyExtAuthzHttp:
                  # Replace with <service-name>.<namespace>.svc.cluster.local
                  service: "ak-outpost-authentik-embedded-outpost.authentik.svc.cluster.local"
                  port: "9000"
                  pathPrefix: "/outpost.goauthentik.io/auth/envoy"
                  headersToDownstreamOnAllow:
                      - cookie
                  headersToUpstreamOnAllow:
                      - set-cookie
                      - x-authentik-*
                  includeRequestHeadersInCheck:
                      - cookie

Afterwards, you can create AuthorizationPolicy resources to protect your applications like this:

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
    name: authentik-policy
    namespace: istio-system
spec:
    selector:
        matchLabels:
            istio: ingressgateway
    action: CUSTOM
    provider:
        name: "authentik"
    rules:
        - to:
              - operation:
                    hosts:
                        # You can create a single resource and list all Domain names here, or create multiple resources
                        - "app.company"

Caddy​

info

Requires authentik 2022.8

Use the following configuration:

app.company {
    # always forward outpost path to actual outpost
    reverse_proxy /outpost.goauthentik.io/* http://outpost.company:9000

    # forward authentication to outpost
    forward_auth http://outpost.company:9000 {
        uri /outpost.goauthentik.io/auth/caddy

        # capitalization of the headers is important, otherwise they will be empty
        copy_headers X-Authentik-Username X-Authentik-Groups X-Authentik-Email X-Authentik-Name X-Authentik-Uid X-Authentik-Jwt X-Authentik-Meta-Jwks X-Authentik-Meta-Outpost X-Authentik-Meta-Provider X-Authentik-Meta-App X-Authentik-Meta-Version

        # optional, in this config trust all private ranges, should probably be set to the outposts IP
        trusted_proxies private_ranges
    }

    # actual site configuration below, for example
    reverse_proxy localhost:1234
}

If you're trying to proxy to an upstream over HTTPS, you need to set the Host header to the value they expect for it to work correctly.

reverse_proxy /outpost.goauthentik.io/* https://outpost.company {
    header_up Host {http.reverse_proxy.upstream.hostport}
}