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 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

Request Authentication (JWT)

Basic JWT Verification

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

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

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

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

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

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

# 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

# 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

• Istio Request Authentication
• JWT Authentication