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Set up service security with Envoy

Use the instructions in this guide to configure authentication and authorization for services deployed with Traffic Director and Envoy proxies. For complete information about Traffic Director service security, see Traffic Director service security.

Requirements

Before you configure service security for Traffic Director with Envoy, make sure that your setup meets the following prerequisites:

Prepare for setup

The following sections describe the tasks you need to complete before you set up Traffic Director security service. These tasks are:

  • Updating the Google Cloud CLI
  • Setting up variables
  • Enabling the APIs required for Traffic Director to work with Certificate Authority Service

Update the gcloud command-line tool

To update the Google Cloud CLI, run the following on your local machine:

gcloud components update

Set up variables

Set the following variables so that you can copy and paste code with consistent values as you work through the example in this document. Use the following values.

  • PROJECT_ID: Substitute the ID of your project.
  • CLUSTER_NAME: Substitute the cluster name you want to us, for example, secure-td-cluster.
  • ZONE: Substitute the zone where your cluster is located. your cluster is located.
  • GKE_CLUSTER_URL: Substitute https://container.googleapis.com/v1/projects/PROJECT_ID/locations/ZONE/clusters/CLUSTER_NAME
  • WORKLOAD_POOL: Substitute PROJECT_ID.svc.id.goog
  • K8S_NAMESPACE: Substitute default.
  • DEMO_CLIENT_KSA: Substitute the name of your client Kubernetes service account.
  • DEMO_SERVER_KSA: Substitute the name of your server Kubernetes service account.
  • PROJNUM: Substitute the project number of your project, which you can determine from the Google Cloud console or with this command:

    gcloud projects describe PROJECT_ID --format="value(projectNumber)"
    
  • SA_GKE: Substitute service-PROJNUM@container-engine-robot.iam.gserviceaccount.com

  • CLUSTER_VERSION: Substitute the most recent version available. You can find this in the Rapid channel release notes. The minimum required version is 1.21.4-gke.1801. This is the GKE cluster version to use in this example.

Set the values here:

# Substitute your project ID
PROJECT_ID=PROJECT_ID


# GKE cluster name and zone for this example.
CLUSTER_NAME=CLUSTER_NAME
ZONE=ZONE

# GKE cluster URL derived from the above
GKE_CLUSTER_URL="https://container.googleapis.com/v1/projects/PROJECT_ID/locations/ZONE/clusters/CLUSTER_NAME"

# Workload pool to be used with the GKE cluster
WORKLOAD_POOL="PROJECT_ID.svc.id.goog"

# Kubernetes namespace to run client and server demo.
K8S_NAMESPACE=K8S_NAMESPACE
DEMO_CLIENT_KSA=DEMO_CLIENT_KSA
DEMO_SERVER_KSA=DEMO_SERVER_KSA

# Compute other values
# Project number for your project
PROJNUM=PROJNUM

CLUSTER_VERSION=CLUSTER_VERSION
SA_GKE=service-PROJNUM@container-engine-robot.iam.gserviceaccount.com

Enable the APIs

Use the gcloud services enable command to enable all of the APIs you need to set up Traffic Director security with Certificate Authority Service.

gcloud services enable \
   container.googleapis.com \
   cloudresourcemanager.googleapis.com \
   compute.googleapis.com \
   trafficdirector.googleapis.com \
   networkservices.googleapis.com \
   networksecurity.googleapis.com \
   privateca.googleapis.com \
   gkehub.googleapis.com

Create or update a GKE cluster

Traffic Director service security depends on the CA Service integration with GKE. The GKE cluster must meet the following requirements in addition to the requirements for setup:

  • Use a minimum cluster version of 1.21.4-gke.1801. If you need features that are in a later version, you can obtain that version from the rapid release channel.
  • The GKE cluster must be enabled and configured with mesh certificates, as described in Creating certificate authorities to issue certificates.
  1. Create a new cluster that uses Workload Identity. If you are updating an existing cluster, skip to the next step. The value you give for --tags must match the name passed to the --target-tags flag for the firewall-rules create command in the section Create the health check, firewall rule, and backend service.

    # Create a GKE cluster with GKE managed mesh certificates.
    gcloud container clusters create CLUSTER_NAME \
      --release-channel=rapid \
      --scopes=cloud-platform \
      --image-type=cos_containerd \
      --machine-type=e2-standard-2 \
      --zone=ZONE \
      --workload-pool=PROJECT_ID.svc.id.goog \
      --enable-mesh-certificates \
      --cluster-version=CLUSTER_VERSION \
      --enable-ip-alias \
      --tags=allow-health-checks \
      --workload-metadata=GKE_METADATA
    

    Cluster creation might take several minutes to complete.

  2. If you are using an existing cluster, turn on Workload Identity and GKE mesh certificates. Make sure that the cluster was created with the --enable-ip-alias flag, which cannot be used with the update command.

    gcloud container clusters update CLUSTER_NAME \
      --enable-mesh-certificates
    
  3. Run the following command to switch to the new cluster as the default cluster for your kubectl commands:

    gcloud container clusters get-credentials CLUSTER_NAME \
      --zone ZONE
    

Deploying in a multi-cluster environment

If you are deploying in a multi-cluster environment, follow the general procedure described in this section. These instructions assume that client Pods are running in one cluster and server Pods are running in the other cluster.

  1. Create or update the clusters using the instructions in the previous section.

  2. Capture the Pod IP address ranges for each cluster using the following command:

    gcloud compute firewall-rules list \
      --filter="name~gke-{CLUSTER_NAME}-[0-9a-z]*-all" \
      --format="value(sourceRanges)"
    

    For example, for clusters called cluster-a and cluster-b, the commands return results such as the following:

    cluster-a, pod CIDR: 10.4.0.0/14, node network tag: gke-cluster-a-9cd18751-node
    cluster-b, pod CIDR: 10.8.0.0/14, node network tag: gke-cluster-b-acd14479-node
    
  3. Create VPC firewall rules that allow the clusters to communicate with each other. For example, the following command creates a firewall rule that allows the cluster-a pod IP addresses to communicate with cluster-b nodes:

    gcloud compute firewall-rules create per-cluster-a-pods \
      --allow="tcp,udp,icmp,esp,ah,sctp" \
      --target-tags="gke-cluster-b-acd14479-node"
    

    The following command creates a firewall rule that allows the cluster-b pod IP addresses to communicate with cluster-a nodes:

    gcloud compute firewall-rules create per-cluster-b-pods \
      --allow="tcp,udp,icmp,esp,ah,sctp" \
      --target-tags="gke-cluster-a-9cd18751-node"
    

Register clusters with a fleet

Register the cluster that you created or updated in Creating a GKE cluster with a fleet. Registering the cluster makes it easier for you to configure clusters across multiple projects.

Note that these steps can take up to ten minutes each to complete.

  1. Register your cluster with the Hub:

    gcloud container hub memberships register CLUSTER_NAME \
      --gke-cluster=ZONE/CLUSTER_NAME \
      --enable-workload-identity \
      --manifest-output-file=MANIFEST-FILE_NAME
    

    Replace the variables as follows:

    • CLUSTER_NAME: Your cluster's name.
    • ZONE: Your cluster's zone.
    • MANIFEST-FILE_NAME: The file path where these commands generate the manifest for registration.

    When the registration process succeeds, you see a message such as the following:

    Finished registering the cluster CLUSTER_NAME with the Hub.
  2. Apply the generated manifest file to your cluster:

    kubectl apply -f MANIFEST-FILE_NAME
    

    When the application process succeeds, you see messages such as the following:

    namespace/gke-connect created
    serviceaccount/connect-agent-sa created
    podsecuritypolicy.policy/gkeconnect-psp created
    role.rbac.authorization.k8s.io/gkeconnect-psp:role created
    rolebinding.rbac.authorization.k8s.io/gkeconnect-psp:rolebinding created
    role.rbac.authorization.k8s.io/agent-updater created
    rolebinding.rbac.authorization.k8s.io/agent-updater created
    role.rbac.authorization.k8s.io/gke-connect-agent-20210416-01-00 created
    clusterrole.rbac.authorization.k8s.io/gke-connect-impersonation-20210416-01-00 created
    clusterrolebinding.rbac.authorization.k8s.io/gke-connect-impersonation-20210416-01-00 created
    clusterrolebinding.rbac.authorization.k8s.io/gke-connect-feature-authorizer-20210416-01-00 created
    rolebinding.rbac.authorization.k8s.io/gke-connect-agent-20210416-01-00 created
    role.rbac.authorization.k8s.io/gke-connect-namespace-getter created
    rolebinding.rbac.authorization.k8s.io/gke-connect-namespace-getter created
    secret/http-proxy created
    deployment.apps/gke-connect-agent-20210416-01-00 created
    service/gke-connect-monitoring created
    secret/creds-gcp create
    
  3. Get the membership resource from the cluster:

    kubectl get memberships membership -o yaml
    

    The output should include the Workoad Identity pool assigned by the Hub, where PROJECT_ID is your project ID:

    workload_identity_pool: PROJECT_ID.svc.id.goog
    

    This means that the cluster registered successfully.

Create certificate authorities to issue certificates

To issue certificates to your Pods, create a CA Service pool and the following certificate authorities (CAs):

  • Root CA. This is the root of trust for all issued mesh certificates. You can use an existing root CA if you have one. Create the root CA in the enterprise tier, which is meant for long-lived, low-volume certificate issuance.
  • Subordinate CA. This CA issues certificates for workloads. Create the subordinate CA in the region where your cluster is deployed. Create the subordinate CA in the devops tier, which is meant for short-lived, high-volume certificate issuance.

Creating a subordinate CA is optional, but we strongly recommend creating one rather than using your root CA to issue GKE mesh certificates. If you decide to use the root CA to issue mesh certificates, ensure that the default config-based issuance mode remains permitted.

The subordinate CA can be in a different region from your cluster, but we strongly recommend creating it in the same region as your cluster to optimize performance. You can, however, create the root and subordinate CAs in different regions without any impact to performance or availability.

These regions are supported for CA Service:

Region name Region description
asia-east1 Taiwan
asia-east2 Hong Kong
asia-northeast1 Tokyo
asia-northeast2 Osaka
asia-northeast3 Seoul
asia-south1 Mumbai
asia-southeast1 Singapore
asia-southeast2 Jakarta
australia-southeast1 Sydney
australia-southeast2 Melbourne
europe-central2 Warsaw
europe-north1 Finland
europe-west1 Belgium
europe-west2 London
europe-west3 Frankfurt
europe-west4 Netherlands
europe-west6 Zürich
northamerica-northeast1 Montréal
southamerica-east1 São Paulo
us-central1 Iowa
us-east1 South Carolina
us-east4 Northern Virginia
us-south1 Dallas
us-west1 Oregon
us-west2 Los Angeles
us-west3 Salt Lake City
us-west4 Las Vegas

The list of supported locations can also be checked by running the following command:

gcloud privateca locations list
  1. Grant the IAM roles/privateca.caManager to individuals who create a CA pool and a CA. Note that for MEMBER, the correct format is user:userid@example.com. If that person is the current user, you can obtain the current user ID with the shell command $(gcloud auth list --filter=status:ACTIVE --format="value(account)").

    gcloud projects add-iam-policy-binding PROJECT_ID \
      --member=MEMBER \
      --role=roles/privateca.caManager
    
  2. Grant the role role/privateca.admin for CA Service to individuals who need to modify IAM policies, where MEMBER is an individual who needs this access, specifically, any individuals who perform the steps below that grant the privateca.auditor and privateca.certificateManager roles:

    gcloud projects add-iam-policy-binding PROJECT_ID \
      --member=MEMBER \
      --role=roles/privateca.admin
    
  3. Create the root CA Service pool.

    gcloud privateca pools create ROOT_CA_POOL_NAME \
      --location ROOT_CA_POOL_LOCATION \
      --tier enterprise
    
  4. Create a root CA.

    gcloud privateca roots create ROOT_CA_NAME --pool ROOT_CA_POOL_NAME \
      --subject "CN=ROOT_CA_NAME, O=ROOT_CA_ORGANIZATION" \
      --key-algorithm="ec-p256-sha256" \
      --max-chain-length=1 \
      --location ROOT_CA_POOL_LOCATION
    

    For this demonstration setup, use the following values for the variables:

    • ROOT_CA_POOL_NAME=td_sec_pool
    • ROOT_CA_NAME=pkcs2-ca
    • ROOT_CA_POOL_LOCATION=us-east1
    • ROOT_CA_ORGANIZATION="TestCorpLLC"
  5. Create the subordinate pool and subordinate CA. Ensure that the default config-based issuance mode remains permitted.

    gcloud privateca pools create SUBORDINATE_CA_POOL_NAME \
      --location SUBORDINATE_CA_POOL_LOCATION \
      --tier devops
    
    gcloud privateca subordinates create SUBORDINATE_CA_NAME \
      --pool SUBORDINATE_CA_POOL_NAME \
      --location SUBORDINATE_CA_POOL_LOCATION \
      --issuer-pool ROOT_CA_POOL_NAME \
      --issuer-location ROOT_CA_POOL_LOCATION \
      --subject "CN=SUBORDINATE_CA_NAME, O=SUBORDINATE_CA_ORGANIZATION" \
      --key-algorithm "ec-p256-sha256" \
      --use-preset-profile subordinate_mtls_pathlen_0
    

    For this demonstration setup, use the following values for the variables:

    • SUBORDINATE_CA_POOL_NAME="td-ca-pool"
    • SUBORDINATE_CA_POOL_LOCATION=us-east1
    • SUBORDINATE_CA_NAME="td-ca"
    • SUBORDINATE_CA_ORGANIZATION="TestCorpLLC"
    • ROOT_CA_POOL_NAME=td_sec_pool
    • ROOT_CA_POOL_LOCATION=us-east1
  6. Grant the IAM privateca.auditor role for the root CA pool to allow access from the GKE service account:

    gcloud privateca pools add-iam-policy-binding ROOT_CA_POOL_NAME \
     --location ROOT_CA_POOL_LOCATION \
     --role roles/privateca.auditor \
     --member="serviceAccount:service-PROJNUM@container-engine-robot.iam.gserviceaccount.com"
    
  7. Grant the IAM privateca.certificateManager role for the subordinate CA pool to allow access from the GKE service account:

    gcloud privateca pools add-iam-policy-binding SUBORDINATE_CA_POOL_NAME \
      --location SUBORDINATE_CA_POOL_LOCATION \
      --role roles/privateca.certificateManager \
      --member="serviceAccount:service-PROJNUM@container-engine-robot.iam.gserviceaccount.com"
    
  8. Save the following WorkloadCertificateConfig YAML configuration to tell your cluster how to issue mesh certificates:

    apiVersion: security.cloud.google.com/v1
    kind: WorkloadCertificateConfig
    metadata:
      name: default
    spec:
      # Required. The CA service that issues your certificates.
      certificateAuthorityConfig:
        certificateAuthorityServiceConfig:
          endpointURI: ISSUING_CA_POOL_URI
    
      # Required. The key algorithm to use. Choice of RSA or ECDSA.
      #
      # To maximize compatibility with various TLS stacks, your workloads
      # should use keys of the same family as your root and subordinate CAs.
      #
      # To use RSA, specify configuration such as:
      #   keyAlgorithm:
      #     rsa:
      #       modulusSize: 4096
      #
      # Currently, the only supported ECDSA curves are "P256" and "P384", and the only
      # supported RSA modulus sizes are 2048, 3072 and 4096.
      keyAlgorithm:
        rsa:
          modulusSize: 4096
    
      # Optional. Validity duration of issued certificates, in seconds.
      #
      # Defaults to 86400 (1 day) if not specified.
      validityDurationSeconds: 86400
    
      # Optional. Try to start rotating the certificate once this
      # percentage of validityDurationSeconds is remaining.
      #
      # Defaults to 50 if not specified.
      rotationWindowPercentage: 50
    
    

    Replace the following:

    • The project ID of the project in which your cluster runs:
      PROJECT_ID
    • The fully qualified URI of the CA that issues your mesh certificates (ISSUING_CA_POOL_URI). This can be either your subordinate CA (recommended) or your root CA. The format is:
      //privateca.googleapis.com/projects/PROJECT_ID/locations/SUBORDINATE_CA_POOL_LOCATION/caPools/SUBORDINATE_CA_POOL_NAME
  9. Save the following TrustConfig YAML configuration to tell your cluster how to trust the issued certificates:

    apiVersion: security.cloud.google.com/v1
    kind: TrustConfig
    metadata:
      name: default
    spec:
      # You must include a trustStores entry for the trust domain that
      # your cluster is enrolled in.
      trustStores:
      - trustDomain: PROJECT_ID.svc.id.goog
        # Trust identities in this trustDomain if they appear in a certificate
        # that chains up to this root CA.
        trustAnchors:
        - certificateAuthorityServiceURI: ROOT_CA_POOL_URI
    

    Replace the following:

    • The project ID of the project in which your cluster runs:
      PROJECT_ID
    • The fully qualified URI of the root CA pool (ROOT_CA_POOL_URI). The format is:
      //privateca.googleapis.com/projects/PROJECT_ID/locations/ROOT_CA_POOL_LOCATION/caPools/ROOT_CA_POOL_NAME
  10. Apply the configurations to your cluster:

    kubectl apply -f WorkloadCertificateConfig.yaml
    kubectl apply -f TrustConfig.yaml
    

Configure Identity and Access Management

To create the resources required for the setup, you must have the compute.NetworkAdmin role. This role contains all the necessary permissions to create, update, delete, list, and use (that is, referencing this in other resources) the required resources. If you are the owner-editor of your project, you automatically have this role.

Note that the networksecurity.googleapis.com.clientTlsPolicies.use and networksecurity.googleapis.com.serverTlsPolicies.use are not enforced when you reference these resources in the backend service and target HTTPS proxy resources.

If these permissions are enforced in the future and you are using the compute.NetworkAdmin role, then you will not notice any issues when this check is enforced.

If you are using custom roles and this check is enforced in the future, you must make sure to include the respective .use permission. Otherwise, in the future, you might find that your custom role does not have the necessary permissions to refer to clientTlsPolicy or serverTlsPolicy from the backend service or target HTTPS proxy, respectively.

The following instructions let the default service account access the Traffic Director Security API and create the Kubernetes service accounts.

  1. Configure IAM to allow the default service account to access the Traffic Director security API.

    GSA_EMAIL=$(gcloud iam service-accounts list --format='value(email)' \
       --filter='displayName:Compute Engine default service account')
    
    gcloud projects add-iam-policy-binding PROJECT_ID \
      --member serviceAccount:${GSA_EMAIL} \
      --role roles/trafficdirector.client
    
  2. Set up Kubernetes service accounts. The client and server deployments in the following sections use the Knames of the Kubernetes server and client service accounts.

    kubectl create serviceaccount --namespace K8S_NAMESPACE DEMO_SERVER_KSA
    kubectl create serviceaccount --namespace K8S_NAMESPACE DEMO_CLIENT_KSA
    
  3. Allow the Kubernetes service accounts to impersonate the default Compute Engine service account by creating an IAM policy binding between the two. This binding allows the Kubernetes service account to act as the default Compute Engine service account.

    gcloud iam service-accounts add-iam-policy-binding  \
      --role roles/iam.workloadIdentityUser \
      --member "serviceAccount:PROJECT_ID.svc.id.goog[K8S_NAMESPACE/DEMO_SERVER_KSA]" ${GSA_EMAIL}
    
    gcloud iam service-accounts add-iam-policy-binding  \
      --role roles/iam.workloadIdentityUser  \
      --member "serviceAccount:PROJECT_ID.svc.id.goog[K8S_NAMESPACE/DEMO_CLIENT_KSA]" ${GSA_EMAIL}
    
  4. Annotate the Kubernetes service accounts to associate them with the default Compute Engine service account.

    kubectl annotate --namespace K8S_NAMESPACE \
      serviceaccount DEMO_SERVER_KSA \
      iam.gke.io/gcp-service-account=${GSA_EMAIL}
    
    kubectl annotate --namespace K8S_NAMESPACE \
      serviceaccount DEMO_CLIENT_KSA \
      iam.gke.io/gcp-service-account=${GSA_EMAIL}
    

Set up Traffic Director

Use the following instructions to install the sidecar injector, set up a test service, and complete other deployment tasks.

Install the Envoy sidecar injector in the cluster

Use the instructions in both of the following sections of the Traffic Director setup for GKE Pods with automatic Envoy injection to deploy and enable Envoy sidecar injection in your cluster:

Make sure that you complete both sets of instructions before you set up a test service.

Set up a test service

After you install the Envoy sidecar injector, use these instructions to set up a test service for your deployment.

wget -q -O -  https://storage.googleapis.com/traffic-director/security/ga/service_sample.yaml | sed -e s/DEMO_SERVER_KSA_PLACEHOLDER/DEMO_SERVER_KSA/g > service_sample.yaml

kubectl apply -f service_sample.yaml

The file service_sample.yaml contains the podspec for your demo server application. There are some annotations that are specific to Traffic Director security.

Traffic Director proxy metadata

The podspec specifies the proxyMetadata annotation:

spec:
...
      annotations:
        cloud.google.com/proxyMetadata: '{"app": "payments"}'
...

When the Pod is initialized, the sidecar proxy picks up this annotation and transmits it to Traffic Director. Traffic Director can then use this information to send back filtered configuration:

  • Later in this guide, note that the endpoint policy specifies an endpoint matcher.
  • The endpoint matcher specifies that only clients that present a label with name app and value payments receive the filtered configuration.

Use mesh certificates and keys signed by CA Service

The podspec specifies the enableManagedCerts annotation:

spec:
...
      annotations:
        ...
        cloud.google.com/enableManagedCerts: "true"
...

When the Pod is initialized, CA Service signed certificates and keys are automatically mounted on the local sidecar proxy filesystem.

Configuring the inbound traffic interception port

The podspec specifies the includeInboundPorts annotation:

spec:
...
      annotations:
        ...
        cloud.google.com/includeInboundPorts: "8000"
...

This is the port on which your server application listens for connections. When the Pod is initialized, the sidecar proxy picks up this annotation and transmits it to Traffic Director. Traffic Director can then use this information to send back filtered configuration which intercepts all incoming traffic to this port and can apply security policies on it.

The health check port must be different from the application port. Otherwise, the same security policies will apply to incoming connections to the health check port which may lead to the connections being declined which results in the server incorrectly marked as unhealthy.

Configure GKE services with NEGs

GKE services must be exposed through network endpoint groups (NEGs) so that you can configure them as backends of a Traffic Director backend service. The service_sample.yaml package provided with this setup guide uses the NEG name service-test-neg in the following annotation:

...
metadata:
  annotations:
    cloud.google.com/neg: '{"exposed_ports": {"80":{"name": "service-test-neg"}}}'
spec:
  ports:
  - port: 80
    name: service-test
    protocol: TCP
    targetPort: 8000

You do not need to change the service_sample.yaml file.

Saving the NEG's name

Save the NEG's name in the NEG_NAME variable:

NEG_NAME="service-test-neg"

Deploy a client application to GKE

Run the following command to launch a demonstration client with an Envoy proxy as a sidecar, which you need to demonstrate the security features.

wget -q -O -  https://storage.googleapis.com/traffic-director/security/ga/client_sample.yaml | sed -e s/DEMO_CLIENT_KSA_PLACEHOLDER/DEMO_CLIENT_KSA/g > client_sample.yaml

kubectl apply -f client_sample.yaml

The client podspec only includes the enableManagedCerts annotation. This is required to mount the necessary volumes for GKE managed mesh certificates and keys which are signed by the CA Service instance.

Configure Traffic Director Google Cloud resources

Follow the steps in Configuring Traffic Director with Cloud Load Balancing components. Make sure to verify that the traffic from the sample client is routed to the sample service.

Traffic Director configuration is complete and you can now configure authentication and authorization policies.

Set up service-to-service security

Use the instructions in the following sections to set up service-to-service security.

Enable mTLS in the mesh

To set up mTLS in your mesh, you must secure outbound traffic to the backend service and secure inbound traffic to the endpoint.

Format for policy references

Note the following required format for referring to server TLS, client TLS, and authorization policies:

projects/PROJECT_ID/locations/global/[serverTlsPolicies|clientTlsPolicies|authorizationPolicies]/[server-tls-policy|client-mtls-policy|authz-policy]

For example:

projects/PROJECT_ID/locations/global/serverTlsPolicies/server-tls-policy
projects/PROJECT_ID/locations/global/clientTlsPolicies/client-mtls-policy
projects/PROJECT_ID/locations/global/authorizationPolicies/authz-policy

Secure outbound traffic to the backend service

To secure outbound traffic, you first create a client TLS policy that does the following:

  • Uses google_cloud_private_spiffe as the plugin for clientCertificate, which programs Envoy to use GKE managed mesh certificates as the client identity.
  • Uses google_cloud_private_spiffe as the plugin for serverValidationCa which programs Envoy to use GKE managed mesh certificates for server validation.

Next, you attach the client TLS policy to the backend service. This does the following:

  • Applies the authentication policy from the client TLS policy to outbound connections to endpoints of the backend service.
  • SAN (Subject Alternative Names) instructs the client to assert the exact identity of the server that it's connecting to.
  1. Create the client TLS policy in a file client-mtls-policy.yaml:

    name: "client-mtls-policy"
    clientCertificate:
      certificateProviderInstance:
        pluginInstance: google_cloud_private_spiffe
    serverValidationCa:
    - certificateProviderInstance:
        pluginInstance: google_cloud_private_spiffe
    
  2. Import the client TLS policy:

    gcloud network-security client-tls-policies import client-mtls-policy \
        --source=client-mtls-policy.yaml --location=global
    
  3. Attach the client TLS policy to the backend service. This enforces mTLS authentication on all outbound requests from the client to this backend service.

    gcloud compute backend-services export td-gke-service \
        --global --destination=demo-backend-service.yaml
    

    Append the following lines to demo-backend-service.yaml:

    securitySettings:
      clientTlsPolicy: projects/PROJECT_ID/locations/global/clientTlsPolicies/client-mtls-policy
      subjectAltNames:
        - "spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_SERVER_KSA"
    
  4. Import the values:

    gcloud compute backend-services import td-gke-service \
        --global --source=demo-backend-service.yaml
    
  5. Optionally, run the following command to check whether the request fails. This is an expected failure, because the client expects certificates from the endpoint, but the endpoint is not programmed with a security policy.

    # Get the name of the Podrunning Busybox.
    BUSYBOX_POD=$(kubectl get po -l run=client -o=jsonpath='{.items[0].metadata.name}')
    
    # Command to execute that tests connectivity to the service service-test.
    TEST_CMD="wget -q -O - service-test; echo"
    
    # Execute the test command on the pod.
    kubectl exec -it $BUSYBOX_POD -c busybox -- /bin/sh -c "$TEST_CMD"
    

    You see output such as this:

    wget: server returned error: HTTP/1.1 503 Service Unavailable
    

Secure inbound traffic to the endpoint

To secure inbound traffic, you first create a server TLS policy that does the following:

  • Uses google_cloud_private_spiffe as the plugin for serverCertificate, which programs Envoy to use GKE managed mesh certificates as the server identity.
  • Uses google_cloud_private_spiffe as the plugin for clientValidationCa, which programs Envoy to use GKE managed mesh certificates for client validation.
  1. Save the server TLS policy values in a file called server-mtls-policy.yaml.

    name: "server-mtls-policy"
    serverCertificate:
      certificateProviderInstance:
        pluginInstance: google_cloud_private_spiffe
    mtlsPolicy:
      clientValidationCa:
      - certificateProviderInstance:
          pluginInstance: google_cloud_private_spiffe
    
  2. Create the server TLS policy:

    gcloud network-security server-tls-policies import server-mtls-policy \
        --source=server-mtls-policy.yaml --location=global
    
  3. Create a file called ep_mtls.yaml that contains the endpoint matcher and attach the server TLS policy.

    endpointMatcher:
      metadataLabelMatcher:
        metadataLabelMatchCriteria: MATCH_ALL
        metadataLabels:
        - labelName: app
          labelValue: payments
    name: "ep"
    serverTlsPolicy: projects/PROJECT_ID/locations/global/serverTlsPolicies/server-mtls-policy
    type: SIDECAR_PROXY
    
  4. Import the endpoint matcher.

    gcloud network-services endpoint-policies import ep \
        --source=ep_mtls.yaml --location=global
    

Validate the setup

Run the following curl command. If the request finishes successfully, you see x-forwarded-client-cert in the output. The header is printed only when the connection is an mTLS connection.

# Get the name of the Podrunning Busybox.
BUSYBOX_POD=$(kubectl get po -l run=client -o=jsonpath='{.items[0].metadata.name}')

# Command to execute that tests connectivity to the service service-test.
TEST_CMD="wget -q -O - service-test; echo"

# Execute the test command on the pod.
kubectl exec -it $BUSYBOX_POD -c busybox -- /bin/sh -c "$TEST_CMD"

You see output such as the following:

GET /get HTTP/1.1
Host: service-test
content-length: 0
x-envoy-internal: true
accept: */*
x-forwarded-for: 10.48.0.6
x-envoy-expected-rq-timeout-ms: 15000
user-agent: curl/7.35.0
x-forwarded-proto: http
x-request-id: redacted
x-forwarded-client-cert: By=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_SERVER_KSA;Hash=Redacted;Subject="Redacted;URI=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_CLIENT_KSA

Note that the x-forwarded-client-cert header is inserted by the server side Envoy and contains its own identity (server) and the identity of the source client. Because we see both the client and server identities, this is a signal of a mTLS connection.

Configure service-level access with an authorization policy

These instructions create an authorization policy that allows requests that are sent by the DEMO_CLIENT_KSA account in which the hostname is service-test, the port is 8000, and the HTTP method is GET. Before you create authorization policies, read the caution in Restrict access using authorization.

  1. Create an authorization policy by creating a file called authz-policy.yaml.

    action: ALLOW
    name: authz-policy
    rules:
    - sources:
      - principals:
        - spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_CLIENT_KSA
      destinations:
      - hosts:
        - service-test
        ports:
        - 8000
        methods:
        - GET
    
  2. Import the policy:

    gcloud network-security authorization-policies import authz-policy \
      --source=authz-policy.yaml \
      --location=global
    
  3. Update the endpoint policy to reference the new authorization policy by appending the following to the file ep_mtls.yaml:

    authorizationPolicy: projects/PROJECT_ID/locations/global/authorizationPolicies/authz-policy
    

    The endpoint policy now specifies that both mTLS and the authorization policy must be enforced on inbound requests to Pods whose Envoy sidecar proxies present the label app:payments.

  4. Import the policy:

    gcloud network-services endpoint-policies import ep \
        --source=ep_mtls.yaml --location=global
    

Validate the setup

Run the following commands to validate the setup.

# Get the name of the Podrunning Busybox.
BUSYBOX_POD=$(kubectl get po -l run=client -o=jsonpath='{.items[0].metadata.name}')

# Command to execute that tests connectivity to the service service-test.
# This is a valid request and will be allowed.
TEST_CMD="wget -q -O - service-test; echo"

# Execute the test command on the pod.
kubectl exec -it $BUSYBOX_POD -c busybox -- /bin/sh -c "$TEST_CMD"

The expected output is similar to this:

GET /get HTTP/1.1
Host: service-test
content-length: 0
x-envoy-internal: true
accept: */*
x-forwarded-for: redacted
x-envoy-expected-rq-timeout-ms: 15000
user-agent: curl/7.35.0
x-forwarded-proto: http
x-request-id: redacted
x-forwarded-client-cert: By=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_SERVER_KSA;Hash=Redacted;Subject="Redacted;URI=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_CLIENT_KSA

Run the following commands to test whether the authorization policy is correctly refusing invalid requests:

# Failure case
# Command to execute that tests connectivity to the service service-test.
# This is an invalid request and server will reject because the server
# authorization policy only allows GET requests.
TEST_CMD="wget -q -O - service-test --post-data='' ; echo"

# Execute the test command on the pod.
kubectl exec -it $BUSYBOX_POD -c busybox -- /bin/sh -c "$TEST_CMD"

The expected output is similar to this:

<RBAC: access denied HTTP/1.1 403 Forbidden>

Set up ingress gateway security

This section assumes that you completed the service-to-service security section, including setting up your GKE cluster with the sidecar auto-injector, creating a certificate authority, and creating an endpoint policy.

In this section, you deploy an Envoy proxy as an ingress gateway that terminates TLS connections and authorizes requests from a cluster's internal clients.

Terminating TLS at an ingress gateway (click to enlarge)
Terminating TLS at an ingress gateway (click to enlarge)

To set up an ingress gateway to terminate TLS, do the following:

  1. Deploy a Kubernetes service that is reachable using a cluster internal IP address.
    1. The deployment consists of a standalone Envoy proxy that is exposed as a Kubernetes service and connects to Traffic Director.
  2. Create a server TLS policy to to terminate TLS.
  3. Create an authorization policy to authorize incoming requests.

Deploy an ingress gateway service to GKE

Run the following command to deploy the ingress gateway service on GKE:

wget -q -O -  https://storage.googleapis.com/traffic-director/security/ga/gateway_sample_xdsv3.yaml | sed -e s/PROJECT_NUMBER_PLACEHOLDER/PROJNUM/g | sed -e s/NETWORK_PLACEHOLDER/default/g | sed -e s/DEMO_CLIENT_KSA_PLACEHOLDER/DEMO_CLIENT_KSA/g > gateway_sample.yaml

kubectl apply -f gateway_sample.yaml

The file gateway_sample.yaml is the spec for the ingress gateway. The following sections describe some additions to the spec.

Disabling Traffic Director sidecar injection

The gateway_sample.yaml spec deploys an Envoy proxy as the sole container. In previous steps, Envoy was injected as a sidecar to an application container. To avoid having multiple Envoys handle requests, you can disable sidecar injection for this Kubernetes service using the following statement:

sidecar.istio.io/inject: "false"

Mount the correct volume

The gateway_sample.yaml spec mounts the volume gke-workload-certificates. This volume is used in sidecar deployment as well, but it is added automatically by the sidecar injector when it sees the annotation cloud.google.com/enableManagedCerts: "true". The gke-workload-certificates volume contains the GKE-managed SPIFFE certs and keys that are signed by the CA Service instance that you set up.

Set the cluster's internal IP address

Configure the ingress gateway with a service of type ClusterInternal. This creates an internally-resolvable DNS hostname for mesh-gateway. When a client sends a request to mesh-gateway:443, Kubernetes immediately routes the request to the ingress gateway Envoy deployment's port 8080.

Enable TLS on an ingress gateway

Use these instructions to enable TLS on an ingress gateway.

  1. Create a server TLS policy resource to terminate TLS connections, with the values in a file called server-tls-policy.yaml:

    description: tls server policy
    name: server-tls-policy
    serverCertificate:
      certificateProviderInstance:
        pluginInstance: google_cloud_private_spiffe
    
  2. Import the server TLS policy:

    gcloud network-security server-tls-policies import server-tls-policy \
        --source=server-tls-policy.yaml --location=global
    
  3. Create a new URL map that routes all requests to the td-gke-service backend service. The ingress gateway handles incoming requests and sends them to Pods belonging to the td-gke-service backend service.

    gcloud compute url-maps create td-gke-ig-url-map \
       --default-service=td-gke-service
    
  4. Create a new target HTTPS proxy in the file td-gke-https-proxy.yaml and attach the previously created URL map and server TLS policy. This configures the Envoy proxy ingress gateway to terminate incoming TLS traffic.

    kind: compute#targetHttpsProxy
    name: td-gke-https-proxy
    proxyBind: true
    urlMap: https://www.googleapis.com/compute/beta/projects/PROJECT_ID/global/urlMaps/td-gke-ig-url-map
    serverTlsPolicy: projects/PROJECT_ID/locations/global/serverTlsPolicies/server-tls-policy
    
  5. Import the policy:

    gcloud compute target-https-proxies import td-gke-https-proxy \
       --global --source=td-gke-https-proxy.yaml
    
  6. Create a new forwarding rule and attach the target HTTPS proxy. This configures the Envoy proxy to listen on port 8080 and apply the routing and security policies defined in td-gke-https-proxy.

    gcloud compute forwarding-rules create td-gke-gateway-forwarding-rule --global \
      --load-balancing-scheme=INTERNAL_SELF_MANAGED --address=0.0.0.0 \
      --target-https-proxy=td-gke-https-proxy --ports 8080 \
      --network default
    
  7. Optionally, update the authorization policy on the backends to allow requests when all of the following conditions are met:

    • Requests sent by DEMO_CLIENT_KSA. (The ingress gateway deployment uses the DEMO_CLIENT_KSA service account.)
    • Requests with host mesh-gateway or service-test
    • Port: 8000

    You do not need to run these commands unless you configured an authorization policy for your backends. If there is no authorization policy on the endpoint or it does not contain host or source principal match in the authorization policy, then request are allowed without this step. Add these values to authz-policy.yaml.

    action: ALLOW
    name: authz-policy
    rules:
    - sources:
      - principals:
        - spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_CLIENT_KSA
      destinations:
      - hosts:
        - service-test
        - mesh-gateway
        ports:
        - 8000
        methods:
        - GET
    
  8. Import the policy:

    gcloud network-security authorization-policies import authz-policy \
      --source=authz-policy.yaml \
      --location=global
    

Validate the ingress gateway deployment

You use a new container called debug to send requests to the ingress gateway to validate the deployment.

In the following spec, the annotation "sidecar.istio.io/inject":"false" keeps the Traffic Director sidecar injector from automatically injecting a sidecar proxy. There is no sidecar to help the debug container in request routing. The container must connect to the ingress gateway for routing.

The spec includes the --no-check-certificate flag, which ignores server certificate validation. The debug container does not have the certificate authority validation certificates necessary to valid certificates signed by CA Service that are used by the ingress gateway to terminate TLS.

In a production environment, we recommend that you download the CA Service validation certificate and mount or install it on your client. After you install the validation certificate, remove the --no-check-certificate option of the wget command.

Run the following command:

kubectl run -i --tty --rm debug --image=busybox --restart=Never  --overrides='{ "metadata": {"annotations": { "sidecar.istio.io/inject":"false" } } }'  -- /bin/sh -c "wget --no-check-certificate -qS -O - https://mesh-gateway; echo"

You see output similar to this:

GET / HTTP/1.1
Host: 10.68.7.132
x-forwarded-client-cert: By=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_SERVER_KSA;Hash=Redacted;Subject="Redacted;URI=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_CLIENT_KSA
x-envoy-expected-rq-timeout-ms: 15000
x-envoy-internal: true
x-request-id: 5ae429e7-0e18-4bd9-bb79-4e4149cf8fef
x-forwarded-for: 10.64.0.53
x-forwarded-proto: https
content-length: 0
user-agent: Wget

Run the following negative test command:

# Negative test
# Expect this to fail because gateway expects TLS.
kubectl run -i --tty --rm debug --image=busybox --restart=Never  --overrides='{ "metadata": {"annotations": { "sidecar.istio.io/inject":"false" } } }'  -- /bin/sh -c "wget --no-check-certificate -qS -O - http://mesh-gateway:443/headers; echo"

You see output similar to the following:

wget: error getting response: Connection reset by peer

Run the following negative test command:

# Negative test.
# AuthorizationPolicy applied on the endpoints expect a GET request. Otherwise
# the request is denied authorization.
kubectl run -i --tty --rm debug --image=busybox --restart=Never  --overrides='{ "metadata": {"annotations": { "sidecar.istio.io/inject":"false" } } }'  -- /bin/sh -c "wget --no-check-certificate -qS -O - https://mesh-gateway --post-data=''; echo"

You see output similar to the following:

HTTP/1.1 403 Forbidden
wget: server returned error: HTTP/1.1 403 Forbidden

Setting up an authorization policy for the ingress gateway

The authorization policy that you set up here lets the ingress gateway allow requests into the mesh when all of the following conditions are met:

  • Host: mesh-gateway
  • Port: 8080
  • path: *
  • HTTP method GET
  1. Create an authorization policy in the file authz-gateway-policy.yaml:

    action: ALLOW
    name: authz-gateway-policy
    rules:
    - destinations:
      - hosts:
        - mesh-gateway
        ports:
        - 8080
        methods:
        - GET
    
  2. Import the values in the file:

    gcloud network-security authorization-policies import authz-gateway-policy \
       --source=authz-gateway-policy.yaml  --location=global
    
  3. Edit the file td-gke-https-proxy.yaml by adding this to it:

    authorizationPolicy: projects/PROJECT_ID/locations/global/authorizationPolicies/authz-gateway-policy
    
  4. Import the file td-gke-https-proxy.yaml again:

    gcloud compute target-https-proxies import td-gke-https-proxy \
       --global --source=td-gke-https-proxy.yaml
    

Validate the deployment

Run the following command to validate your deployment.

# On your localhost.
kubectl run -i --tty --rm debug --image=busybox --restart=Never  --overrides='{ "metadata": {"annotations": { "sidecar.istio.io/inject":"false" } } }'  -- /bin/sh -c "wget --no-check-certificate -qS -O - https://mesh-gateway; echo"

You see output similar to the following:

GET / HTTP/1.1
Host: 35.196.50.2
x-forwarded-client-cert: By=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_SERVER_KSA;Hash=Redacted;Subject="Redacted;URI=spiffe://PROJECT_ID.svc.id.goog/ns/K8S_NAMESPACE/sa/DEMO_CLIENT_KSA
x-envoy-expected-rq-timeout-ms: 15000
user-agent: curl/7.72.0
x-forwarded-proto: https
content-length: 0
x-envoy-internal: true
x-request-id: 98bec135-6df8-4082-8edc-b2c23609295a
accept: */*
x-forwarded-for: 10.142.0.7

Run the following negative test command:

# Negative test. Expect failure because only POST method is allowed by \
# authz-gateway-policy
kubectl run -i --tty --rm debug --image=busybox --restart=Never  --overrides='{ "metadata": {"annotations": { "sidecar.istio.io/inject":"false" } } }'  -- /bin/sh -c "wget --no-check-certificate -qS -O - https://mesh-gateway/ --post-data=''; echo"

You see output similar to the following:

wget: server returned error: HTTP/1.1 403 Forbidden

Delete the deployment

You can optionally run these commands to delete the deployment you created using this guide.

To delete the cluster, run this command:

gcloud container clusters delete CLUSTER_NAME --zone ZONE --quiet

To delete the resources you created, run these commands:

gcloud compute forwarding-rules delete td-gke-forwarding-rule --global --quiet
gcloud compute forwarding-rules delete td-gke-gateway-forwarding-rule --global \
    --quiet
gcloud compute target-http-proxies delete td-gke-proxy  --quiet
gcloud compute target-https-proxies delete td-gke-https-proxy  --quiet
gcloud compute url-maps delete td-gke-url-map  --quiet
gcloud compute url-maps delete td-gke-ig-url-map  --quiet
gcloud compute backend-services delete td-gke-service --global --quiet
cloud compute network-endpoint-groups delete service-test-neg --zone ZONE --quiet
gcloud compute firewall-rules delete fw-allow-health-checks --quiet
gcloud compute health-checks delete td-gke-health-check --quiet
gcloud network-services endpoint-policies delete ep \
    --location=global --quiet
gcloud network-security authorization-policies delete authz-gateway-policy \
   --location=global --quiet
gcloud network-security authorization-policies delete authz-policy \
    --location=global --quiet
gcloud network-security client-tls-policies delete client-mtls-policy \
    --location=global --quiet
gcloud network-security server-tls-policies delete server-tls-policy \
    --location=global --quiet
gcloud network-security server-tls-policies delete server-mtls-policy \
    --location=global --quiet

Troubleshooting

This section contains information on how to fix issues you encounter during security service setup.

Connection failures

If the connection fails with anupstream connect error or disconnect/reset before headers error, examine the Envoy logs, where you might see one of the following log messages:

gRPC config stream closed: 5, Requested entity was not found

gRPC config stream closed: 2, no credential token is found

If you see these errors in the Envoy log, it is likely that the service account token is mounted incorrectly, or it is using a different audience, or both.

For more information, see Error messages in the Envoy logs indicate a configuration problem.

Pods not created

To troubleshoot this issue, see Troubleshooting automatic deployments for GKE Pods.

Envoy not authenticating with Traffic Director

When Envoy (envoy-proxy) connects to Traffic Director to fetch the xDS configuration, it uses Workload Identity (WI) and the Compute Engine VM default service account (unless the bootstrap was changed). If the authentication fails, then Envoy does not get into the ready state.

Unable to create a cluster with --workload-identity-certificate-authority flag

If you see this error, make sure that you're running the most recent version of the Google Cloud CLI:

gcloud components update

###

If the Pods stay in a pending state during the setup process, increase the CPU and memory resources for the Pods in your deployment spec.

Unable to create cluster with the --enable-mesh-certificates flag

Ensure that you are running the latest version of the gcloud CLI:

gcloud components update

Note that the --enable-mesh-certificates flag works only with gcloud beta.

Pods don't start

Pods that use GKE mesh certificates might fail to start if certificate provisioning is failing. This can happen in situations like the following:

  • The WorkloadCertificateConfig or the TrustConfig is misconfigured or missing.
  • CSRs aren't being approved.

You can check whether certificate provisioning is failing by checking the Pod events.

  1. Check the status of your Pod:

    kubectl get pod -n POD_NAMESPACE POD_NAME
    

    Replace the following:

    • POD_NAMESPACE: the namespace of your Pod.
    • POD_NAME: the name of your Pod.
  2. Check recent events for your Pod:

    kubectl describe pod -n POD_NAMESPACE POD_NAME
    
  3. If certificate provisioning is failing, you will see an event with Type=Warning, Reason=FailedMount, From=kubelet, and a Message field that begins with MountVolume.SetUp failed for volume "gke-workload-certificates". The Message field contains troubleshooting information.

    Events:
      Type     Reason       Age                From       Message
      ----     ------       ----               ----       -------
      Warning  FailedMount  13s (x7 over 46s)  kubelet    MountVolume.SetUp failed for volume "gke-workload-certificates" : rpc error: code = Internal desc = unable to mount volume: store.CreateVolume, err: unable to create volume "csi-4d540ed59ef937fbb41a9bf5380a5a534edb3eedf037fe64be36bab0abf45c9c": caPEM is nil (check active WorkloadCertificateConfig)
    
  4. See the following troubleshooting steps if the reason your Pods don't start is because of misconfigured objects, or because of rejected CSRs.

WorkloadCertificateConfig or TrustConfig is misconfigured

Ensure that you created the WorkloadCertificateConfig and TrustConfig objects correctly. You can diagnose misconfigurations on either of these objects using kubectl.

  1. Retrieve the current status.

    For WorkloadCertificateConfig:

    kubectl get WorkloadCertificateConfig default -o yaml
    

    For TrustConfig:

    kubectl get TrustConfig default -o yaml
    
  2. Inspect the status output. A valid object will have a condition with type: Ready and status: "True".

    status:
      conditions:
      - lastTransitionTime: "2021-03-04T22:24:11Z"
        message: WorkloadCertificateConfig is ready
        observedGeneration: 1
        reason: ConfigReady
        status: "True"
        type: Ready
    

    For invalid objects, status: "False" appears instead. Thereasonand message field contain additional troubleshooting details.

CSRs are not approved

If something goes wrong during the CSR approval process, you can check the error details in the type: Approved and type: Issued conditions of the CSR.

  1. List relevant CSRs using kubectl:

    kubectl get csr \
      --field-selector='spec.signerName=spiffe.gke.io/spiffe-leaf-signer'
    
  2. Choose a CSR that is either Approved and not Issued, or is not Approved.

  3. Get details for the selected CSR using kubectl:

    kubectl get csr CSR_NAME -o yaml
    

    Replace CSR_NAME with the name of the CSR you chose.

A valid CSR has a condition with type: Approved and status: "True", and a valid certificate in the status.certificate field:

status:
  certificate: <base64-encoded data>
  conditions:
  - lastTransitionTime: "2021-03-04T21:58:46Z"
    lastUpdateTime: "2021-03-04T21:58:46Z"
    message: Approved CSR because it is a valid SPIFFE SVID for the correct identity.
    reason: AutoApproved
    status: "True"
    type: Approved

Troubleshooting information for invalid CSRs appears in the message and reason fields.

Applications cannot use issued mTLS credentials

  1. Verify that the certificate has not expired:

    cat /var/run/secrets/workload-spiffe-credentials/certificates.pem | openssl x509 -text -noout | grep "Not After"
    
  2. Check that the key type you used is supported by your application.

    cat /var/run/secrets/workload-spiffe-credentials/certificates.pem | openssl x509 -text -noout | grep "Public Key Algorithm" -A 3
    
  3. Check that the issuing CA uses the same key family as the certificate key.

    1. Get the status of the CA Service (Preview) instance:

      gcloud privateca ISSUING_CA_TYPE describe ISSUING_CA_NAME \
        --location ISSUING_CA_LOCATION
      

      Replace the following:

      • ISSUING_CA_TYPE: the issuing CA type, which must be either subordinates or roots.
      • ISSUING_CA_NAME: the name of the issuing CA.
      • ISSUING_CA_LOCATION: the region of the issuing CA.
    2. Check that the keySpec.algorithm in the output is the same key algorithm you defined in the WorkloadCertificateConfig YAML manifest. The output looks like this:

      config:
        ...
        subjectConfig:
          commonName: td-sub-ca
          subject:
            organization: TestOrgLLC
          subjectAltName: {}
      createTime: '2021-05-04T05:37:58.329293525Z'
      issuingOptions:
        includeCaCertUrl: true
      keySpec:
        algorithm: RSA_PKCS1_2048_SHA256
       ...
      

Certificates get rejected

  1. Verify that the peer application uses the same trust bundle to verify the certificate.
  2. Verify that the certificate has not expired:

    cat /var/run/secrets/workload-spiffe-credentials/certificates.pem | openssl x509 -text -noout | grep "Not After"
    
  3. Verify that the client code, if not using the gRPC Go Credentials Reloading API, periodically refreshes the credentials from the filesystem.

  4. Verify that your workloads are in the same trust domain as your CA. GKE mesh certificates supports communication between workloads in a single trust domain.