mtls-configuration

# mTLS Configuration Comprehensive guide to implementing mutual TLS for zero-trust service mesh communication. ## Do not use this skill when - The task is unrelated to mtls configuration - You need a different domain or tool outside this scope ## Instructions - Clarify goals, constraints, and required inputs. - Apply relevant best practices and validate outcomes. - Provide actionable steps and verification. - If detailed examples are required, open `resources/implementation-playbook.md`. ## Use this skill when - Implementing zero-trust networking - Securing service-to-service communication - Certificate rotation and management - Debugging TLS handshake issues - Compliance requirements (PCI-DSS, HIPAA) - Multi-cluster secure communication ## Core Concepts ### 1. mTLS Flow ``` ┌─────────┐ ┌─────────┐ │ Service │ │ Service │ │ A │ │ B │ └────┬────┘ └────┬────┘ │ │ ┌────┴────┐ TLS Handshake ┌────┴────┐ │ Proxy │◄───────────────────────────►│ Proxy │ │(Sidecar)│ 1. ClientHello │(Sidecar)│ │ │ 2. ServerHello + Cert │ │ │ │ 3. Client Cert │ │ │ │ 4. Verify Both Certs │ │ │ │ 5. Encrypted Channel │ │ └─────────┘ └─────────┘ ``` ### 2. Certificate Hierarchy ``` Root CA (Self-signed, long-lived) │ ├── Intermediate CA (Cluster-level) │ │ │ ├── Workload Cert (Service A) │ └── Workload Cert (Service B) │ └── Intermediate CA (Multi-cluster) │ └── Cross-cluster certs ``` ## Templates ### Template 1: Istio mTLS (Strict Mode) ```yaml # Enable strict mTLS mesh-wide apiVersion: security.istio.io/v1beta1 kind: PeerAuthentication metadata: name: default namespace: istio-system spec: mtls: mode: STRICT --- # Namespace-level override (permissive for migration) apiVersion: security.istio.io/v1beta1 kind: PeerAuthentication metadata: name: default namespace: legacy-namespace spec: mtls: mode: PERMISSIVE --- # Workload-specific policy apiVersion: security.istio.io/v1beta1 kind: PeerAuthentication metadata: name: payment-service namespace: production spec: selector: matchLabels: app: payment-service mtls: mode: STRICT portLevelMtls: 8080: mode: STRICT 9090: mode: DISABLE # Metrics port, no mTLS ``` ### Template 2: Istio Destination Rule for mTLS ```yaml apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: default namespace: istio-system spec: host: "*.local" trafficPolicy: tls: mode: ISTIO_MUTUAL --- # TLS to external service apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: external-api spec: host: api.external.com trafficPolicy: tls: mode: SIMPLE caCertificates: /etc/certs/external-ca.pem --- # Mutual TLS to external service apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: partner-api spec: host: api.partner.com trafficPolicy: tls: mode: MUTUAL clientCertificate: /etc/certs/client.pem privateKey: /etc/certs/client-key.pem caCertificates: /etc/certs/partner-ca.pem ``` ### Template 3: Cert-Manager with Istio ```yaml # Install cert-manager issuer for Istio apiVersion: cert-manager.io/v1 kind: ClusterIssuer metadata: name: istio-ca spec: ca: secretName: istio-ca-secret --- # Create Istio CA secret apiVersion: v1 kind: Secret metadata: name: istio-ca-secret namespace: cert-manager type: kubernetes.io/tls data: tls.crt: <base64-encoded-ca-cert> tls.key: <base64-encoded-ca-key> --- # Certificate for workload apiVersion: cert-manager.io/v1 kind: Certificate metadata: name: my-service-cert namespace: my-namespace spec: secretName: my-service-tls duration: 24h renewBefore: 8h issuerRef: name: istio-ca kind: ClusterIssuer commonName: my-service.my-namespace.svc.cluster.local dnsNames: - my-service - my-service.my-namespace - my-service.my-namespace.svc - my-service.my-namespace.svc.cluster.local usages: - server auth - client auth ``` ### Template 4: SPIFFE/SPIRE Integration ```yaml # SPIRE Server configuration apiVersion: v1 kind: ConfigMap metadata: name: spire-server namespace: spire data: server.conf: | server { bind_address = "0.0.0.0" bind_port = "8081" trust_domain = "example.org" data_dir = "/run/spire/data" log_level = "INFO" ca_ttl = "168h" default_x509_svid_ttl = "1h" } plugins { DataStore "sql" { plugin_data { database_type = "sqlite3" connection_string = "/run/spire/data/datastore.sqlite3" } } NodeAttestor "k8s_psat" { plugin_data { clusters = { "demo-cluster" = { service_account_allow_list = ["spire:spire-agent"] } } } } KeyManager "memory" { plugin_data {} } UpstreamAuthority "disk" { plugin_data { key_file_path = "/run/spire/secrets/bootstrap.key" cert_file_path = "/run/spire/secrets/bootstrap.crt" } } } --- # SPIRE Agent DaemonSet (abbreviated) apiVersion: apps/v1 kind: DaemonSet metadata: name: spire-agent namespace: spire spec: selector: matchLabels: app: spire-agent template: spec: containers: - name: spire-agent image: ghcr.io/spiffe/spire-agent:1.8.0 volumeMounts: - name: spire-agent-socket mountPath: /run/spire/sockets volumes: - name: spire-agent-socket hostPath: path: /run/spire/sockets type: DirectoryOrCreate ``` ### Template 5: Linkerd mTLS (Automatic) ```yaml # Linkerd enables mTLS automatically # Verify with: # linkerd viz edges deployment -n my-namespace # For external services without mTLS apiVersion: policy.linkerd.io/v1beta1 kind: Server metadata: name: external-api namespace: my-namespace spec: podSelector: matchLabels: app: my-app port: external-api proxyProtocol: HTTP/1 # or TLS for passthrough --- # Skip TLS for specific port apiVersion: v1 kind: Service metadata: name: my-service annotations: config.linkerd.io/skip-outbound-ports: "3306" # MySQL ``` ## Certificate Rotation ```bash # Istio - Check certificate expiry istioctl proxy-config secret deploy/my-app -o json | \ jq '.dynamicActiveSecrets[0].secret.tlsCertificate.certificateChain.inlineBytes' | \ tr -d '"' | base64 -d | openssl x509 -text -noout # Force certificate rotation kubectl rollout restart deployment/my-app # Check Linkerd identity linkerd identity -n my-namespace ``` ## Debugging mTLS Issues ```bash # Istio - Check if mTLS is enabled istioctl authn tls-check my-service.my-namespace.svc.cluster.local # Verify peer authentication kubectl get peerauthentication --all-namespaces # Check destination rules kubectl get destinationrule --all-namespaces # Debug TLS handshake istioctl proxy-config log deploy/my-app --level debug kubectl logs deploy/my-app -c istio-proxy | grep -i tls # Linkerd - Check mTLS status linkerd viz edges deployment -n my-namespace linkerd viz tap deploy/my-app --to deploy/my-backend ``` ## Best Practices ### Do's - **Start with PERMISSIVE** - Migrate gradually to STRICT - **Monitor certificate expiry** - Set up alerts - **Use short-lived certs** - 24h or less for workloads - **Rotate CA periodically** - Plan for CA rotation - **Log TLS errors** - For debugging and audit ### Don'ts - **Don't disable mTLS** - For convenience in production - **Don't ignore cert expiry** - Automate rotation - **Don't use self-signed certs** - Use proper CA hierarchy - **Don't skip verification** - Verify the full chain ## Resources - [Istio Security](https://istio.io/latest/docs/concepts/security/) - [SPIFFE/SPIRE](https://spiffe.io/) - [cert-manager](https://cert-manager.io/) - [Zero Trust Architecture (NIST)](https://www.nist.gov/publications/zero-trust-architecture) ## Limitations - Use this skill only when the task clearly matches the scope described above. - Do not treat the output as a substitute for environment-specific validation, testing, or expert review. - Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.