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Authentication ​

Istio supports service-to-service authentication (Peer Authentication) and end-user authentication (Request Authentication).

Table of Contents ​

  1. Authentication Overview
  2. Request Authentication (JWT)
  3. OAuth/OIDC Integration
  4. Practical Examples
  5. Troubleshooting

Authentication Overview ​

Istio Authentication

Istio provides two types of authentication:

  1. Peer Authentication (Service-to-Service Authentication)

    • Service-to-service authentication using mTLS
    • Identity verification based on SPIFFE ID
    • Configured with PeerAuthentication CRD

  2. Request Authentication (End-User Authentication)

    • User authentication based on JWT tokens
    • Integration with OAuth/OIDC providers
    • Configured with RequestAuthentication CRD

Sequence diagram of the Istio request-authentication flow: a user logs in with an OAuth/OIDC provider to get a JWT, presents it to Istio's Request Authentication filter at the gateway, which verifies the token and either forwards the request to the application or rejects it back to the user.

Request Authentication (JWT) ​

Basic JWT Verification ​

yaml
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: jwt-auth
  namespace: default
spec:
  selector:
    matchLabels:
      app: myapp
  jwtRules:
  - issuer: "https://accounts.google.com"
    jwksUri: "https://www.googleapis.com/oauth2/v3/certs"

Multiple Issuer Support ​

yaml
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: multi-issuer-jwt
  namespace: default
spec:
  jwtRules:
  - issuer: "https://accounts.google.com"
    jwksUri: "https://www.googleapis.com/oauth2/v3/certs"
  - issuer: "https://login.microsoftonline.com/tenant-id/v2.0"
    jwksUri: "https://login.microsoftonline.com/tenant-id/discovery/v2.0/keys"

Custom Header ​

yaml
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: jwt-custom-header
  namespace: default
spec:
  jwtRules:
  - issuer: "https://auth.example.com"
    jwksUri: "https://auth.example.com/.well-known/jwks.json"
    fromHeaders:
    - name: "X-Auth-Token"
      prefix: "Bearer "

OAuth/OIDC Integration ​

AWS Cognito ​

yaml
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: cognito-jwt
  namespace: default
spec:
  jwtRules:
  - issuer: "https://cognito-idp.{region}.amazonaws.com/{userPoolId}"
    jwksUri: "https://cognito-idp.{region}.amazonaws.com/{userPoolId}/.well-known/jwks.json"

Keycloak ​

yaml
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: keycloak-jwt
  namespace: default
spec:
  jwtRules:
  - issuer: "https://keycloak.example.com/auth/realms/myrealm"
    jwksUri: "https://keycloak.example.com/auth/realms/myrealm/protocol/openid-connect/certs"

Auth0 ​

yaml
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: auth0-jwt
  namespace: default
spec:
  jwtRules:
  - issuer: "https://your-tenant.auth0.com/"
    jwksUri: "https://your-tenant.auth0.com/.well-known/jwks.json"
    audiences:
    - "https://your-api.example.com"

Practical Examples ​

JWT Verification + Authorization ​

yaml
# JWT Verification
apiVersion: security.istio.io/v1
kind: RequestAuthentication
metadata:
  name: jwt-auth
  namespace: default
spec:
  selector:
    matchLabels:
      app: myapp
  jwtRules:
  - issuer: "https://auth.example.com"
    jwksUri: "https://auth.example.com/.well-known/jwks.json"
---
# Deny requests without JWT
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: require-jwt
  namespace: default
spec:
  selector:
    matchLabels:
      app: myapp
  action: DENY
  rules:
  - from:
    - source:
        notRequestPrincipals: ["*"]

Troubleshooting ​

JWT Verification Failure ​

bash
# 1. Check RequestAuthentication
kubectl get requestauthentication -A
kubectl describe requestauthentication <name> -n <namespace>

# 2. Decode JWT token
echo "<jwt-token>" | cut -d'.' -f2 | base64 -d | jq

# 3. Verify JWKS endpoint
curl https://auth.example.com/.well-known/jwks.json

# 4. Check Envoy logs
kubectl logs <pod-name> -c istio-proxy -n <namespace> | grep JWT

References ​