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SSO with KeyCloak and Oauth2-Proxy

Centralized authentication and Single-Sign On can be implemented using Keycloak. Keycloak is an opensource Identity Access Management solution, providing centralized authentication and authorization services based on standard protocols and provides support for OpenID Connect, OAuth 2.0, and SAML.

sequenceDiagram
  actor User
  participant Keycloak
  participant Application
    User->>Application: User enters URL of an Application
    Application->>Keycloak: Redirects to Keycloak
    Keycloak->>User: Login page
    User->>Keycloak: User gives credentials
    Keycloak-->>Keycloak: Validates User
    Keycloak->>Application: if Valid, Redirect to Application
    Keycloak-->>User: Invalid credentials

Some of the GUIs of the Pi Cluster, Grafana or Kibana, SSO can be configured, so authentication can be done using Keycloak instead of local accounts.

Note:

Elasticsearch/Kibana SSO integration using OpenID Connect is not available in community edition. So, SSO won’t be configured for this component. Grafana SSO capability is enabled configuring OAuth2.0/OpenID Connect authentication. Follow instructions in Documentation: Monitoring (Prometheus) on how to integrate Grafana with Keycloak.

For those applications not providing any authentication capability (i.e. Longhorn, Prometheus, etc.), Ingress controller-based External Authentication can be configured. Ingress NGINX supports OAuth2-based external authentication mechanism using Oauth2-Proxy. See Ingress NGINX external Oauth authentication document Oauth2-proxy can be integrated with OpenId-Connect IAM, such us Keycloak.

picluster-sso

Keycloak Installation

For installing Keycloak Bitnami’s helm chart will be used. This helm chart bootstraps a Keycloak deployment on Kubernetes using as backend a PostgreSQL database

Step 1: Add Bitnami Helm repository:

helm repo add bitnami https://charts.bitnami.com/bitnami

Step 2: Fetch the latest charts from the repository:
```
helm repo update
```
Step 3: Create namespace
```
kubectl create namespace keycloak
```

Step 4: Create file keycloak-values.yml

global:
  storageClass: longhorn

# Run in production mode behind NGINX proxy terminating TLS sessions
production: true
# ref: https://www.keycloak.org/server/reverseproxy
proxyHeaders: xforwarded

# Admin user
auth:
  adminUser: admin
# postgresSQL
postgresql:
  enabled: true
  auth:
    username: keycloak
    database: keycloak
# Ingress config
ingress:
  enabled: true
  ingressClassName: "nginx"
  pathType: Prefix
  annotations:
    cert-manager.io/cluster-issuer: ca-issuer
    # Increasing proxy buffer size to avoid
    # https://stackoverflow.com/questions/57503590/upstream-sent-too-big-header-while-reading-response-header-from-upstream-in-keyc
    nginx.ingress.kubernetes.io/proxy-buffers-number: "4"
    nginx.ingress.kubernetes.io/proxy-buffer-size: "16k"
  hostname: sso.picluster.ricsanfre.com
  tls: true

With this configuration:

Keycloak is deployed to run behind NGINX proxy terminating TLS connections. proxyHeaders variable need to be used.
PostgreSQL is deployed in standalone mode.
Ingress resource is configured

Note: With this configuration all passwords (Keycloak’s admin password and postgreSQL passwords are generated randomly. If helm chart is upgraded, it might cause issues generating a new passwords if the existing ones are not provided when executing helm upgrade command. See details in bitnami’s keycloak helm chart documentation: How to manage passwords

Step 5: Install Keycloak in keycloak namespace

helm install keycloak bitnami/keycloak -f keycloak-values.yml --namespace keycloak

Step 6: Check status of Keycloak pods
```
kubectl get pods -n keycloak
```

Step 7: Get keycloak admin user password

kubectl get secret keycloak -o jsonpath='{.data.admin-password}' -n keycloak | base64 -d && echo

Step 8: connect to keycloak admin console https://sso.picluster.ricsanfre.com

Log in using ‘admin’ user and password obtained in step 7.

Alternative installation using external secret (GitOps)

Keycloak admin password and postgreSQL passwords can be provided during helm installation in values.yaml file. Alternatively, it can be provided in an external secret.

Step 1: Create secret containing admin password and posgresql passwords:

apiVersion: v1
kind: Secret
metadata:
    name: keycloak-secret
    namespace: keycloak
type: kubernetes.io/basic-auth
data:
    admin-password: <`echo -n 'supersecret1' | base64`>
    postgresql-admin-password: <`echo -n 'supersecret2' | base64`>
    password: <`echo -n 'supersecret3' | base64`>

Step 2: Add externalSecret to keycloak-values.yaml

# Admin user
auth:
    existingSecret: keycloak-secret
    adminUser: admin
  
# postgresSQL
postgresql:
  enabled: true
  auth:
    username: keycloak
    database: keycloak
    existingSecret: keycloak-secret
    secretKeys:
      adminPasswordKey: postgresql-admin-password
      userPasswordKey: password
  architecture: standalone

Alternative installation using external database

Instead of using Bitnami’s PosgreSQL subchart, an external PosgreSQL database can be used. For example, using CloudNative-PG a, keycload database cluster can be created. See details on how to install CloudNative-PG in “Databases”.

Step 1. Create secret for keycloak admin user

apiVersion: v1
kind: Secret
metadata:
    name: keycloak-secret
    namespace: keycloak
type: kubernetes.io/basic-auth
data:
    admin-password: <`echo -n 'supersecret1' | base64`>

Step 2. Create secret for external database

apiVersion: v1
kind: Secret
metadata:
  name: keycloak-db-secret
  namespace: keycloak
  labels:
    cnpg.io/reload: "true"
type: kubernetes.io/basic-auth
data:
  username: <`echo -n 'keycloak' | base64`>
  password: <`echo -n 'supersecret' | base64`>  

Step 1. Create CloudNative PG database for keycloak

apiVersion: postgresql.cnpg.io/v1
kind: Cluster
metadata:
  name: keycloak-db
  namespace: keycloak
spec:
  instances: 3
  imageName: ghcr.io/cloudnative-pg/postgresql:16.3-4
  storage:
    size: 10Gi
    storageClass: longhorn
  monitoring:
    enablePodMonitor: true
  bootstrap:
    initdb:
      database: keycloak
      owner: keycloak
      secret:
        name: keycloak-db-secret
  # Backup to external Minio (Optional)
  backup:
    barmanObjectStore:
      data:
        compression: bzip2
      wal:
        compression: bzip2
        maxParallel: 8
      destinationPath: s3://k3s-barman/keycloak-db
      endpointURL: https://s3.ricsanfre.com:9091
      s3Credentials:
        accessKeyId:
          name: keycloak-minio-secret
          key: AWS_ACCESS_KEY_ID
        secretAccessKey:
          name: keycloak-minio-secret
          key: AWS_SECRET_ACCESS_KEY
    retentionPolicy: "30d"

Step 3. Add external database configuration to helm values.yaml

# Admin user
auth:
    existingSecret: keycloak-secret
    adminUser: admin
# External DB: https://github.com/bitnami/charts/tree/main/bitnami/keycloak#use-an-external-database
postgresql:
  enabled: false

externalDatabase:
  host: "keycloak-db-rw"
  port: 5432
  database: keycloak
  existingSecret: "keycloak-db-secret"
  existingSecretUserKey: "username"
  existingSecretPasswordKey: "password"

Keycloak Configuration

Pi Cluster realm configuration

Step 1: Login as admin to Keycloak console

Open URL: https://sso.picluster.ricsanfre.com
Step 9: Create a new realm ‘picluster’

Follow procedure in Keycloak documentation:Keycloak: Creating a Realm

Configure Oauth2-Proxy Client

OAuth2-Proxy client application need to be configured within ‘picluster’ realm.

Procedure in Keycloak documentation: Keycloak: Creating an OpenID Connect client

Follow procedure in Oauth2-Proxy: Keycloak OIDC Auth Provider Configuration to provide the proper configuration.

Step 1: Create a new OIDC client in ‘picluster’ Keycloak realm by navigating to: Clients -> Create client
- Provide the following basic configuration:
  - Client Type: ‘OpenID Connect’
  - Client ID: ‘oauth2-proxy’
- Click Next.
- Provide the following ‘Capability config’
  - Client authentication: ‘On’
  - Authentication flow
    - Standard flow ‘selected’
    - Direct access grants ‘deselect’
- Click Next
- Provide the following ‘Logging settings’
  - Valid redirect URIs: https://ouath2-proxy.picluster.ricsanfre.com/oauth2/callback
- Save the configuration.
Step 2: Locate oauth2-proxy client credentials

Under the Credentials tab you will now be able to locate oauth2-proxy client’s secret.
Step 3: Configure a dedicated audience mapper for the client
- Navigate to Clients -> oauth2-proxy client -> Client scopes.
- Access the dedicated mappers pane by clicking ‘oauth2-proxy-dedicated’, located under Assigned client scope. (It should have a description of “Dedicated scope and mappers for this client”)
- Click on ‘Configure a new mapper’ and select ‘Audience’
- Provide following data:
  - Name ‘aud-mapper-oauth2-proxy’
  - Included Client Audience select oauth2-proxy client’s id from the dropdown.
  - Add to ID token ‘On’
  - Add to access token ‘On’ OAuth2 proxy can be set up to pass both the access and ID JWT tokens to your upstream services.
- Save the configuration.

Automatic import of Realm configuration

Realm configuration can be exported or imported to/from JSON files.

Once realm and clients are configured manually configuration can be exported to JSON file. See Keycloak export import configuration.

Realm configuration can be imported automatically from json file when deploying helm chart. See Importing realm on start-up

New ConfigMap, containing the JSON files to be imported need to be mounted by keycloak PODs as /opt/bitnami/keycloak/data/import. --import-realm also need to be provided as extra arguments when starting the PODs.

Step 1: Create realm config map containing realm json files to be imported

apiVersion: v1
kind: ConfigMap
metadata:
  name: keycloak-realm-configmap
  namespace: keycloak
data:
  picluster-realm.json: |  
    # JSON file

Step 3: Apply configMap

kubectl apply -f keycloak-realm-configmap.yaml

Step 2: Add to keycloak-values.yaml the following configuration and install helm char

# Importing realm on start-up
# https://www.keycloak.org/server/importExport#_importing_a_realm_during_startup
extraStartupArgs: "--import-realm"
extraVolumes:
  - name: realm-config
    configMap:
      name: keycloak-realm-configmap
extraVolumeMounts:
  - mountPath: /opt/bitnami/keycloak/data/import
    name: realm-config

Proxy Oauth 2.0 Installation

Step 1: Add Helm repository:

helm repo add oauth2-proxy https://oauth2-proxy.github.io/manifests

Step 2: Fetch the latest charts from the repository:
```
helm repo update
```
Step 3: Create namespace
```
kubectl create namespace oauth2-proxy
```

Step 4: Create file oauth2-proxy-values.yml

config:
  # Add config annotations
  annotations: {}
  # OAuth client ID
  # Follow instructions to configure Keycloak client
  # https://oauth2-proxy.github.io/oauth2-proxy/configuration/providers/keycloak_oidc

  # Oauth2 client configuration. From Keycloak configuration
  clientID: "oauth2-proxy"
  clientSecret: "supersecreto"
    
  # Cookie secret
  # Create a new secret with the following command
  # openssl rand -base64 32 | head -c 32 | base64
  cookieSecret: "bG5pRDBvL0VaWis3dksrZ05vYnJLclRFb2VNcVZJYkg="
  # The name of the cookie that oauth2-proxy will create
  # If left empty, it will default to the release name
  cookieName: "oauth2-proxy"

  # Config file
  configFile: |-
    # Provider config
    provider="keycloak-oidc"
    provider_display_name="Keycloak"
    redirect_url="https://oauth2-proxy.picluster.ricsanfre.com/oauth2/callback"
    oidc_issuer_url="https://sso.picluster.ricsanfre.com/realms/picluster"
    code_challenge_method="S256"
    ssl_insecure_skip_verify=true
    # Upstream config
    http_address="0.0.0.0:4180"
    upstreams="file:///dev/null"
    email_domains=["*"]
    cookie_domains=["picluster.ricsanfre.com"]
    cookie_secure=false
    scope="openid"
    whitelist_domains=[".picluster.ricsanfre.com"]
    insecure_oidc_allow_unverified_email="true"

sessionStorage:
  # Can be one of the supported session storage cookie|redis
  type: redis
# Enabling redis backend installation
redis:
  enabled: true
  # standalone redis. No cluster
  architecture: standalone

ingress:
  enabled: true
  className: "nginx"
  pathType: Prefix
  path: /oauth2
  annotations:
    # Enable cert-manager to create automatically the SSL certificate and store in Secret
    # Possible Cluster-Issuer values:
    #   * 'letsencrypt-issuer' (valid TLS certificate using IONOS API)
    #   * 'ca-issuer' (CA-signed certificate, not valid)
    cert-manager.io/cluster-issuer: letsencrypt-issuer
    cert-manager.io/common-name: oauth2-proxy.picluster.ricsanfre.com
    nginx.ingress.kubernetes.io/proxy-buffer-size: "16k"
  hosts:
    - oauth2-proxy.picluster.ricsanfre.com
  tls:
    - hosts:
        - oauth2-proxy.picluster.ricsanfre.com
      secretName: oauth2-proxy-tls  

Step 5: Install helm chart

helm install oauth2-proxy oauth2-proxy/oauth2-proxy -f oauth2-proxy-values.yml --namespace oauth2-proxy

Step 6: Check status oauth2-proxy PODs

kubectl --namespace=oauth2-proxy get pods -l "app=oauth2-proxy"

Alternative installation using external secret (GitOps)

OAuth credentials (clientID, client secret), cookie secret and redis password can be provided from external secret

Tip: About ArgoCD and helm native commands

Redis backend is installed using redis bitnami helm sub-chart. This helm chart creates a random credential for redis backend. When using ArgoCD, helm native commands, like random or lookup, used by the helm chart for generating this random secret are not supported and so oauth2-proxy fails to save any data to redis. See issue bitnami@charts#18130 and issue argocd@argocd#14944

As workaround, the issue can be solved providing the credentials in a external secrets.

Step 1: Create secret containing oauth2-proxy credentials:

apiVersion: v1
kind: Secret
metadata:
    name: oauth2-proxy-secret
    namespace: oauth2-proxy
type: kubernetes.io/basic-auth
data:
  client-id: <`echo -n 'oauth2-proxy' | base64`> 
  client-secret:  <`echo -n 'supersecret | base64`>
  cookie-secret: <`openssl rand -base64 32 | head -c 32 | base64`>
  redis-password: <`openssl rand -base64 32 | head -c 32 | base64`>

client-secret value should be taken from Oauth2-proxy client configuration

Step 2: Add existingSecret to oauth2-proxy-values.yaml and install helm chart

# Admin user
auth:
  existingSecret: oauth2-proxy-secret
  # clientID: "oauth2-proxy"
  # clientSecret: "supersecreto"
  # cookieSecret: "bG5pRDBvL0VaWis3dksrZ05vYnJLclRFb2VNcVZJYkg="
  
sessionStorage:
  type: redis
  redis:
    existingSecret: oauth2-proxy-secret
    passwordKey: redis-password
  
redis:
  enabled: true
  # standalone redis. No cluster
  architecture: standalone
  # Get redis password from existing secret using key redis-password
  auth:
    existingSecret: oauth2-proxy-secret
    existingSecretPasswordKey: redis-password

Configure Ingress external authentication

Following annotations need to be added to any Ingress resource to use Oauth2-proxy authentication

nginx.ingress.kubernetes.io/auth-signin: https://oauth2-proxy.picluster.ricsanfre.com/oauth2/start?rd=https://$host$request_uri
nginx.ingress.kubernetes.io/auth-url: http://oauth2-proxy.oauth2-proxy.svc.cluster.local/oauth2/auth
nginx.ingress.kubernetes.io/proxy-buffer-size: "16k"
nginx.ingress.kubernetes.io/auth-response-headers: Authorization

Last Update: Sep 09, 2024

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