Traefik-based ForwardAuth configuration

This article was last updated on: February 7, 2024 pm

preface

Traefik is a modern HTTP reverse proxy and load balancer that makes it easy to deploy microservices.

Traefik works with multiple existing infrastructure components (Docker, Swarm patterns, Kubernetes, Marathon, Consul, Etcd, Rancher, Amazon ECS…). Integrate and configure yourself automatically and dynamically.

Series:

Today we detail how authentication functionality can be implemented via forwardauth based on Traefik on K8S and integrated with OAuth 2.0 or CAS via ForwardAuth.

ForwardAuth middleware delegates authentication to an external service. If the service response code is 2XX, access is granted and the original request is executed. Otherwise, a response from the authentication server is returned.

ForwardAuth 功能简图

Simple configuration of ForwardAuth

Create the ForwardAuth middleware as follows:

1
2
3
4
5
6
7
8
9
10
11
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: forward-auth
spec:
  forwardAuth:
    # 路径视具体情况而定 
    address: http://your_auth_server/oauth2.0/validate
    authResponseHeaders:
      - Authorization
    trustForwardHeader: true

In addition, generally for security reasons, some security-related headers will be added, as follows:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: secure-header
spec:
  headers:
    browserXssFilter: true
    contentTypeNosniff: true
    customResponseHeaders:
      Cache-Control: max-age=31536000
      Pragma: no-cache
      Set-Cookie: secure
    forceSTSHeader: true
    stsIncludeSubdomains: true
    stsSeconds: 14400

Of course, it is also for safety reasons, it will be used HTTP redirects to HTTPS.

After that, the example configuration for creating an IngressRoute is as follows:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: alertmanager
spec:
  routes:
    - kind: Rule
      match: Host(`e-whisper.com`) && PathPrefix(`/alertmanager/`)
      middlewares:
        - name: redirectshttps
        - name: secure-header
        - name: forward-auth
      services:
        - name: alertmanager
          port: 9093

🎉Finish!

Use OAuth Proxy and Traefik ForwardAuth integration

Create middleware for ForwardAuth 401 errors

Traefik v2 ForwardAuth middleware allows Traefik to pass through the oauth2-agent /oauth2/auth The endpoint authenticates each request and only returns 202 Accepted Response or401 Unauthorizedwithout proxies the entire request.

oauth-errors and oauth-auth Middleware

Purpose: Add headers to OAuth URLs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: auth-headers
spec:
  headers:
    sslRedirect: true
    stsSeconds: 315360000
    browserXssFilter: true
    contentTypeNosniff: true
    forceSTSHeader: true
    sslHost: e-whisper.com
    stsIncludeSubdomains: true
    stsPreload: true
    frameDeny: true

Purpose: Forwardauth

1
2
3
4
5
6
7
8
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: oauth-auth
spec:
  forwardAuth:
    address: https://oauth.e-whisper.com/oauth2/auth
    trustForwardHeader: true

Purpose: ForwardAuth returns 401-403 and redirects to the login page

1
2
3
4
5
6
7
8
9
10
apiVersion: traefik.containo.us/v1alpha1
kind: Middleware
metadata:
  name: oauth-errors
spec:
  errors:
    status:
      - "401-403"
    service: oauth-backend
    query: "/oauth2/sign_in"

oauth’s IngressRoute configuration:

1
2
3
4
5
6
7
8
9
10
11
12
13
apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: oauth
spec:
  routes:
    - kind: Rule
      match: "Host(`e-whisper.com`, `oauth.e-whisper.com`) && PathPrefix(`/oauth2/`)"
      middlewares:
        - name: auth-headers
      services:
        - name: oauth-backend
          port: 4180

IngressRoute configuration for other applications that use oauth:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: alertmanager
spec:
  routes:
    - kind: Rule
      match: Host(`e-whisper.com`) && PathPrefix(`/alertmanager/`)
      middlewares:
        - name: redirectshttps     
        - name: oauth-errors
        - name: oauth-auth
      services:
        - name: alertmanager
          port: 9093

🎉Finish!

📚️ Reference documentation

EOF