Configure transport security

In Anthos Service Mesh 1.5 and later, auto mutual TLS (auto mTLS) is enabled by default. With auto mTLS, a client sidecar proxy automatically detects if the server has a sidecar. The client sidecar sends mTLS to workloads with sidecars and sends plaintext to workloads without sidecars. Note, however, services accept both plaintext and mTLS traffic. As you inject sidecar proxies to your Pods, we recommend that you also configure your services to only accept mTLS traffic.

With Anthos Service Mesh, you can configure your services to only accept mTLS by applying a PeerAuthentication policy. Anthos Service Mesh gives you the flexibility to apply the policy to the entire service mesh, to a namespace, or to an individual workload. When you specify a policy for a specific workload, that policy takes precedence. For example, a workload-specific policy takes precedence over a namespace-specific one. If no policy is specified for the workload, it inherits the policy from the namespace or the mesh.

Enable mutual TLS per namespace

To enable mTLS for all workloads within a particular namespace, use a namespace-wide authentication policy. You specify the namespace it applies to under metadata.

kubectl apply -f - <<EOF
apiVersion: "security.istio.io/v1beta1"
kind: "PeerAuthentication"
metadata:
  name: "AUTH_POLICY_NAME"
  namespace: "NAMESPACE"
spec:
  mtls:
    mode: STRICT
EOF

Expected output: 

peerauthentication.security.istio.io/AUTH_POLICY_NAME created

Enable mutual TLS per workload

To set a PeerAuthentication policy for a specific workload, you must configure the selector section and specify the labels that match the desired workload. However, Anthos Service Mesh can't aggregate workload-level policies for outbound mTLS traffic to a service. You need to configure a destination rule to manage that behavior.

  1. Apply an authentication policy to a specific workload in your namespace:

    cat <<EOF | kubectl apply -n NAMESPACE -f -
apiVersion: "security.istio.io/v1beta1"
kind: "PeerAuthentication"
metadata:
  name: "AUTH_POLICY_NAME"
  namespace: "NAMESPACE"
spec:
  selector:
    matchLabels:
      app: WORKLOAD
  mtls:
    mode: STRICT
EOF

    Expected output:

    peerauthentication.security.istio.io/AUTH_POLICY_NAME created

  2. Configure a matching destination rule:

    cat <<EOF | kubectl apply -n NAMESPACE -f -
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "DEST_RULE_NAME"
spec:
  host: "WORKLOAD.NAMESPACE.svc.cluster.local"
  trafficPolicy:
    tls:
      mode: ISTIO_MUTUAL
EOF

    Expected output:

    destinationrule.networking.istio.io/WORKLOAD created

Enforcing mesh-wide mTLS

To prevent all your services in the mesh from accepting plain-text traffic, set a mesh-wide PeerAuthentication policy with the mTLS mode set to STRICT (the default is PERMISSIVE). The mesh-wide PeerAuthentication policy shouldn't have a selector and must be applied in the root namespace, istio-system. When you deploy the policy, the control plane automatically provisions TLS certificates so that workloads can authenticate with each other.

To enforce mesh-wide mTLS:

kubectl apply -f - <<EOF
apiVersion: "security.istio.io/v1beta1"
kind: "PeerAuthentication"
metadata:
  name: "AUTH_POLICY_NAME"
  namespace: "istio-system"
spec:
  mtls:
    mode: STRICT
EOF

Expected output: 

peerauthentication.security.istio.io/AUTH_POLICY_NAME created

Finding and deleting PeerAuthentication policies

For a list of all the PeerAuthentication polices in the service mesh:

kubectl get peerauthentication --all-namespaces

If there is a PeerAuthentication policy in force, you can delete it with kubectl delete:

kubectl delete peerauthentication -n NAMESPACE AUTH_POLICY_NAME

What's next