Using Cloud Service Mesh egress gateways on GKE clusters: Tutorial

Setting up the infrastructure

Create a VPC network and subnet

1. Create a new VPC network:

   gcloud compute networks create vpc-network \  --subnet-mode custom 

2. Create a subnet for the cluster to run in with pre-assigned secondary IP address ranges for Pods and services. Private Google Access is enabled so that applications with only internal IP addresses can reach Google APIs and services:

   gcloud compute networks subnets create subnet-gke \  --network vpc-network \  --range 10.0.0.0/24 \  --secondary-range pods=10.1.0.0/16,services=10.2.0.0/20 \  --enable-private-ip-google-access 

Configure Cloud NAT

Cloud NAT allows workloads without external IP addresses to connect to destinations on the internet and receive inbound responses from those destinations.

1. Create a Cloud Router:

   gcloud compute routers create nat-router \  --network vpc-network 

2. Add a NAT configuration to the router:

   gcloud compute routers nats create nat-config \  --router nat-router \  --nat-all-subnet-ip-ranges \  --auto-allocate-nat-external-ips 

Create service accounts for each GKE node pool

Create two service accounts for use by the two GKE node pools. A separate service account is assigned to each node pool so that you can apply VPC firewall rules to specific nodes.

1. Create a service account for use by the nodes in the default node pool:

   gcloud iam service-accounts create sa-application-nodes \  --description="SA for application nodes" \  --display-name="sa-application-nodes" 

2. Create a service account for use by the nodes in the gateway node pool:

   gcloud iam service-accounts create sa-gateway-nodes \  --description="SA for gateway nodes" \  --display-name="sa-gateway-nodes" 

Grant permissions to the service accounts

Add a minimal set of IAM roles to the application and gateway service accounts. These roles are required for logging, monitoring, and pulling private container images from Container Registry.

 project_roles=(  roles/logging.logWriter  roles/monitoring.metricWriter  roles/monitoring.viewer  roles/storage.objectViewer  )  for role in "${project_roles[@]}"  do  gcloud projects add-iam-policy-binding ${PROJECT_ID} \  --member="serviceAccount:sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com" \  --role="$role"  gcloud projects add-iam-policy-binding ${PROJECT_ID} \  --member="serviceAccount:sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com" \  --role="$role"  done 

Creating the firewall rules

In the following steps, you apply a firewall rule to the VPC network so that, by default, all egress traffic is denied. Specific connectivity is required for the cluster to function and for gateway nodes to be able to reach destinations outside of the VPC. A minimal set of specific firewall rules overrides the default deny-all rule to allow the necessary connectivity.

1. Create a default (low priority) firewall rule to deny all egress from the VPC network:

   gcloud compute firewall-rules create global-deny-egress-all \  --action DENY \  --direction EGRESS \  --rules all \  --destination-ranges 0.0.0.0/0 \  --network vpc-network \  --priority 65535 \  --description "Default rule to deny all egress from the network." 

2. Create a rule to allow only those nodes with the gateway service account to reach the internet:

   gcloud compute firewall-rules create gateway-allow-egress-web \  --action ALLOW \  --direction EGRESS \  --rules tcp:80,tcp:443 \  --target-service-accounts sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com \  --network vpc-network \  --priority 1000 \  --description "Allow the nodes running the egress gateways to connect to the web" 

3. Allow nodes to the reach the Kubernetes control plane:

   gcloud compute firewall-rules create allow-egress-to-api-server \  --action ALLOW \  --direction EGRESS \  --rules tcp:443,tcp:10250 \  --target-service-accounts sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com,sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com \  --destination-ranges 10.5.0.0/28 \  --network vpc-network \  --priority 1000 \  --description "Allow nodes to reach the Kubernetes API server." 

4. Optional: This firewall rule is not needed if you use Managed Cloud Service Mesh.

   Cloud Service Mesh uses webhooks when injecting sidecar proxies into workloads. Allow the GKE API server to call the webhooks exposed by the service mesh control plane running on the nodes:

   gcloud compute firewall-rules create allow-ingress-api-server-to-webhook \  --action ALLOW \  --direction INGRESS \  --rules tcp:15017 \  --target-service-accounts sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com,sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com \  --source-ranges 10.5.0.0/28 \  --network vpc-network \  --priority 1000 \  --description "Allow the API server to call the webhooks exposed by istiod discovery" 

5. Allow egress connectivity between Nodes and Pods running on the cluster. GKE automatically creates a corresponding ingress rule. No rule is required for Service connectivity because the iptables routing chain always converts Service IP addresses to Pod IP addresses.

   gcloud compute firewall-rules create allow-egress-nodes-and-pods \  --action ALLOW \  --direction EGRESS \  --rules all \  --target-service-accounts sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com,sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com \  --destination-ranges 10.0.0.0/24,10.1.0.0/16 \  --network vpc-network \  --priority 1000 \  --description "Allow egress to other Nodes and Pods" 

6. Allow access to the reserved sets of IP addresses used by Private Google Access for serving Google APIs, Container Registry, and other services:

   gcloud compute firewall-rules create allow-egress-gcp-apis \  --action ALLOW \  --direction EGRESS \  --rules tcp \  --target-service-accounts sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com,sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com \  --destination-ranges 199.36.153.8/30 \  --network vpc-network \  --priority 1000 \  --description "Allow access to the VIPs used by Google Cloud APIs (Private Google Access)" 

7. Allow the Google Cloud health checker service to access pods running in the cluster. See health checks: for more information.

   gcloud compute firewall-rules create allow-ingress-gcp-health-checker \  --action ALLOW \  --direction INGRESS \  --rules tcp:80,tcp:443 \  --target-service-accounts sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com,sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com \  --source-ranges 35.191.0.0/16,130.211.0.0/22,209.85.152.0/22,209.85.204.0/22 \  --network vpc-network \  --priority 1000 \  --description "Allow workloads to respond to Google Cloud health checks" 

Configuring private access to Google Cloud APIs

Private Google Access enables VMs and Pods that only have internal IP addresses to access Google APIs and services. Although Google APIs and services are served from external IPs, traffic from the nodes never leaves the Google network when using Private Google Access.

Enable the Cloud DNS API:

gcloud services enable dns.googleapis.com 

Create a private DNS zone, a CNAME, and A records so that nodes and workloads can connect to Google APIs and services using Private Google Access and the private.googleapis.com hostname:

gcloud dns managed-zones create private-google-apis \  --description "Private DNS zone for Google APIs" \  --dns-name googleapis.com \  --visibility private \  --networks vpc-network gcloud dns record-sets transaction start --zone private-google-apis gcloud dns record-sets transaction add private.googleapis.com. \  --name "*.googleapis.com" \  --ttl 300 \  --type CNAME \  --zone private-google-apis gcloud dns record-sets transaction add "199.36.153.8" \ "199.36.153.9" "199.36.153.10" "199.36.153.11" \  --name private.googleapis.com \  --ttl 300 \  --type A \  --zone private-google-apis gcloud dns record-sets transaction execute --zone private-google-apis 

Configuring private access to Container Registry

Create a private DNS zone, a CNAME and an A record so that nodes can connect to Container Registry using Private Google Access and the gcr.io hostname:

gcloud dns managed-zones create private-gcr-io \  --description "private zone for Container Registry" \  --dns-name gcr.io \  --visibility private \  --networks vpc-network gcloud dns record-sets transaction start --zone private-gcr-io gcloud dns record-sets transaction add gcr.io. \  --name "*.gcr.io" \  --ttl 300 \  --type CNAME \  --zone private-gcr-io gcloud dns record-sets transaction add "199.36.153.8" "199.36.153.9" "199.36.153.10" "199.36.153.11" \  --name gcr.io \  --ttl 300 \  --type A \  --zone private-gcr-io gcloud dns record-sets transaction execute --zone private-gcr-io 

Create a private GKE cluster

1. Find the external IP address of your Cloud Shell so that you can add it to the list of networks that are allowed to access your cluster's API server:

   SHELL_IP=$(dig TXT -4 +short @ns1.google.com o-o.myaddr.l.google.com) 

   After a period of inactivity, the external IP address of your Cloud Shell VM can change. If that happens, you must update your cluster's list of authorized networks. Add the following command to your initialization script:

   cat << 'EOF' >> ./init-egress-tutorial.sh SHELL_IP=$(dig TXT -4 +short @ns1.google.com o-o.myaddr.l.google.com) gcloud container clusters update cluster1 \  --enable-master-authorized-networks \  --master-authorized-networks ${SHELL_IP//\"}/32 EOF 

2. Enable the Google Kubernetes Engine API:

   gcloud services enable container.googleapis.com 

3. Create a private GKE cluster:

   gcloud container clusters create cluster1 \  --enable-ip-alias \  --enable-private-nodes \  --release-channel "regular" \  --enable-master-authorized-networks \  --master-authorized-networks ${SHELL_IP//\"}/32 \  --master-ipv4-cidr 10.5.0.0/28 \  --enable-dataplane-v2 \  --service-account "sa-application-nodes@${PROJECT_ID}.iam.gserviceaccount.com" \  --machine-type "e2-standard-4" \  --network "vpc-network" \  --subnetwork "subnet-gke" \  --cluster-secondary-range-name "pods" \  --services-secondary-range-name "services" \  --workload-pool "${PROJECT_ID}.svc.id.goog" \  --zone ${ZONE} 

   It takes a few minutes for the cluster to be created. The cluster has private nodes with internal IP addresses. Pods and services are assigned IPs from the named secondary ranges that you defined when creating the VPC subnet.

   Cloud Service Mesh with an in-cluster control plane requires the cluster nodes to use a machine type that has at least 4 vCPUs.

   Google recommends that the cluster be subscribed to the "regular" release channel to ensure that nodes are running a Kubernetes version that is supported by Cloud Service Mesh.

   For more information on the prerequisites for running Cloud Service Mesh with an in-cluster control plane, see the in-cluster prerequisites.

   For more information on the requirements and limitations for running managed Cloud Service Mesh see the managed Cloud Service Mesh supported features.

   Workload Identity Federation for GKE is enabled on the cluster. Cloud Service Mesh requires Workload Identity Federation for GKE and is the recommended way to access Google APIs from GKE workloads.

4. Create a node pool called gateway. This node pool is where the egress gateway is deployed. The dedicated=gateway:NoSchedule taint is added to every node in the gateway node pool.

   gcloud container node-pools create "gateway" \  --cluster "cluster1" \  --machine-type "e2-standard-4" \  --node-taints dedicated=gateway:NoSchedule \  --service-account "sa-gateway-nodes@${PROJECT_ID}.iam.gserviceaccount.com" \  --num-nodes "1" 

   Kubernetes taints and tolerations help ensure that only egress gateway Pods run on nodes in the gateway node pool.

5. Download credentials so that you can connect to the cluster with kubectl:

   gcloud container clusters get-credentials cluster1 

6. Verify that the gateway nodes have the correct taint:

   kubectl get nodes -l cloud.google.com/gke-nodepool=gateway -o yaml \ -o=custom-columns='name:metadata.name,taints:spec.taints[?(@.key=="dedicated")]' 

   The output is similar to the following:

   name taints gke-cluster1-gateway-9d65b410-cffs map[effect:NoSchedule key:dedicated value:gateway] 

Installing and setting up Cloud Service Mesh

Follow one of the installation guides for Cloud Service Mesh:

• Managed Cloud Service Mesh
• In-cluster Cloud Service Mesh

Once you have installed Cloud Service Mesh, stop and return to this tutorial without installing ingress or egress gateways.

Install an egress gateway

1. Create a Kubernetes namespace for the egress gateway:

   kubectl create namespace istio-egress 

2. Enable the namespace for injection. The steps depend on your control plane implementation.

   Managed (TD)

   Apply the default injection label to the namespace:

   kubectl label namespace istio-egress \  istio.io/rev- istio-injection=enabled --overwrite 

   Managed (Istiod)

   Recommended: Run the following command to apply the default injection label to the namespace:

    kubectl label namespace istio-egress \  istio.io/rev- istio-injection=enabled --overwrite 

   If you are an existing user with the Managed Istiod control plane: We recommend that you use default injection, but revision-based injection is supported. Use the following instructions:

   1. Run the following command to locate the available release channels:

      kubectl -n istio-system get controlplanerevision 

      The output is similar to the following:

      NAME AGE asm-managed-rapid 6d7h 

      In the output, the value under the NAME column is the revision label that corresponds to the available release channel for the Cloud Service Mesh version.

   2. Apply the revision label to the namespace:

      kubectl label namespace istio-egress \  istio-injection- istio.io/rev=REVISION_LABEL --overwrite 

   In-cluster

   Recommended: Run the following command to apply the default injection label to the namespace:

    kubectl label namespace istio-egress \  istio.io/rev- istio-injection=enabled --overwrite 

   We recommend that you use default injection, but revision-based injection is supported: Use the following instructions:

   1. Use the following command to locate the revision label on istiod:

      kubectl get deploy -n istio-system -l app=istiod -o \  jsonpath={.items[*].metadata.labels.'istio\.io\/rev'}'{"\n"}' 

   2. Apply the revision label to the namespace. In the following command, REVISION_LABEL is the value of the istiod revision label that you noted in the previous step.

      kubectl label namespace istio-egress \  istio-injection- istio.io/rev=REVISION_LABEL --overwrite 

3. Create an operator manifest for the egress gateway:

   cat << EOF > egressgateway-operator.yaml apiVersion: install.istio.io/v1alpha1 kind: IstioOperator metadata:  name: egressgateway-operator  annotations:  config.kubernetes.io/local-config: "true" spec:  profile: empty  revision: REVISION  components:  egressGateways:  - name: istio-egressgateway  namespace: istio-egress  enabled: true  values:  gateways:  istio-egressgateway:  injectionTemplate: gateway  tolerations:  - key: "dedicated"  operator: "Equal"  value: "gateway"  nodeSelector:  cloud.google.com/gke-nodepool: "gateway" EOF 

4. Download the istioctl tool. You must use version 1.16.2-asm.2 or newer even if you are using Cloud Service Mesh version 1.15 or lower. See Downloading the correct istioctl version.

5. After extracting the downloaded archive, set an environment variable to hold the path to the istioctl tool and add it to your initialization script:

   ISTIOCTL=$(find "$(pwd -P)" -name istioctl) echo "ISTIOCTL=\"${ISTIOCTL}\"" >> ./init-egress-tutorial.sh 

6. Create the egress gateway installation manifest using the operator manifest and istioctl:

   ${ISTIOCTL} manifest generate \  --filename egressgateway-operator.yaml \  --output egressgateway \  --cluster-specific 

7. Install the egress gateway:

   kubectl apply --recursive --filename egressgateway/ 

8. Check that the egress gateway is running on nodes in the gateway node pool:

   kubectl get pods -n istio-egress -o wide 

9. The egress gateway pods have affinity for nodes in the gateway node pool and a toleration that lets them run on the tainted gateway nodes. Examine the node affinity and tolerations for the egress gateway pods:

   kubectl -n istio-egress get pod -l istio=egressgateway \  -o=custom-columns='name:metadata.name,node-affinity:spec.affinity.nodeAffinity.requiredDuringSchedulingIgnoredDuringExecution.nodeSelectorTerms,tolerations:spec.tolerations[?(@.key=="dedicated")]' 

   The output is similar to the following:

   name node-affinity tolerations istio-egressgateway-754d9684d5-jjkdz [map[matchExpressions:[map[key:cloud.google.com/gke-nodepool operator:In values:[gateway]]]]] map[key:dedicated operator:Equal value:gateway] 

Enable Envoy access logging

The steps required to enable Envoy access logs depend on your Cloud Service Mesh type, either managed or in-cluster:

Preparing the mesh and a test application

1. Make sure that STRICT mutual TLS is enabled. Apply a default PeerAuthentication policy for the mesh in the istio-system namespace:

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

   You can override this configuration by creating PeerAuthentication resources in specific namespaces.

2. Create namespaces to use for deploying test workloads. Later steps in this tutorial explain how to configure different egress routing rules for each namespace.

   kubectl create namespace team-x kubectl create namespace team-y 

3. Label the namespaces so that they can be selected by Kubernetes network policies:

   kubectl label namespace team-x team=x kubectl label namespace team-y team=y 

4. For Cloud Service Mesh to automatically inject proxy sidecars, you set the control plane revision label on the workload namespaces:

   kubectl label ns team-x istio.io/rev- istio-injection=enabled --overwrite kubectl label ns team-y istio.io/rev- istio-injection=enabled --overwrite 

5. Create a YAML file to use for making test deployments:

   cat << 'EOF' > ./test.yaml apiVersion: v1 kind: ServiceAccount metadata:  name: test --- apiVersion: v1 kind: Service metadata:  name: test  labels:  app: test spec:  ports:  - port: 80  name: http  selector:  app: test --- apiVersion: apps/v1 kind: Deployment metadata:  name: test spec:  replicas: 1  selector:  matchLabels:  app: test  template:  metadata:  labels:  app: test  spec:  serviceAccountName: test  containers:  - name: test  image: gcr.io/google.com/cloudsdktool/cloud-sdk:slim  command: ["/bin/sleep", "infinity"]  imagePullPolicy: IfNotPresent EOF 

6. Deploy the test application to the team-x namespace:

   kubectl -n team-x create -f ./test.yaml 

7. Verify that the test application is deployed to a node in the default pool and that a proxy sidecar container is injected. Repeat the following command until the pod's status is Running:

   kubectl -n team-x get po -l app=test -o wide 

   The output is similar to the following:

   NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES test-d5bdf6f4f-9nxfv 2/2 Running 0 19h 10.1.1.25 gke-cluster1-default-pool-f6c7a51f-wbzj 

   2 out of 2 containers are Running. One container is the test application and the other is the proxy sidecar.

   The Pod is running on a node in the default node pool.

8. Verify that it is not possible to make an HTTP request from the test container to an external site:

   kubectl -n team-x exec -it \  $(kubectl -n team-x get pod -l app=test -o jsonpath={.items..metadata.name}) \  -c test -- curl -v http://example.com 

   An error message from the sidecar proxy is generated because the global-deny-egress-all firewall rule denies the upstream connection.

Using the Sidecar resource to restrict the scope of sidecar proxy configuration

You can use the Sidecar resource to restrict the scope of the egress listener that is configured for sidecar proxies. To reduce configuration bloat and memory usage, it's a good practice to apply a default Sidecar resource for every namespace.

The proxy that Cloud Service Mesh runs in the sidecar is Envoy. In Envoy terminology, a cluster is a logically similar group of upstream endpoints used as destinations for load balancing.

1. Inspect the outbound clusters configured in the Envoy sidecar proxy for the test pod by running the istioctl proxy-config command:

   ${ISTIOCTL} pc c $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}).team-x --direction outbound 

   There are approximately 11 Envoy clusters in the list, including some for the egress gateway.

2. Restrict the proxy configuration to egress routes that have been explicitly defined with service entries in the egress and team-x namespaces. Apply a Sidecar resource to the team-x namespace:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: Sidecar metadata:  name: default  namespace: team-x spec:  outboundTrafficPolicy:  mode: REGISTRY_ONLY  egress:  - hosts:  - 'istio-egress/*'  - 'team-x/*' EOF 

   Setting outbound traffic policy mode to REGISTRY_ONLY restricts the proxy configuration to include only those external hosts that have been explicitly added to the mesh's service registry by defining service entries.

   Setting egress.hosts specifies that the sidecar proxy only selects routes from the egress namespace that are made available by using the exportTo attribute. The 'team-x/*' part includes any routes that have been configured locally in the team-x namespace.

3. View the outbound clusters configured in the Envoy sidecar proxy, and compare them to the list of clusters that were configured before applying the Sidecar resource:

   ${ISTIOCTL} pc c $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}).team-x --direction outbound 

   You see clusters for the egress gateway and one for the test pod itself.

Configuring Cloud Service Mesh to route traffic through the egress gateway

1. Configure a Gateway for HTTP traffic on port 80. The Gateway selects the egress gateway proxy that you deployed to the egress namespace. The Gateway configuration is applied to the egress namespace and handles traffic for any host.

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: Gateway metadata:  name: egress-gateway  namespace: istio-egress spec:  selector:  istio: egressgateway  servers:  - port:  number: 80  name: https  protocol: HTTPS  hosts:  - '*'  tls:  mode: ISTIO_MUTUAL EOF 

2. Create a DestinationRule for the egress gateway with mutual TLS for authentication and encryption. Use a single shared destination rule for all external hosts.

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata:  name: target-egress-gateway  namespace: istio-egress spec:  host: istio-egressgateway.istio-egress.svc.cluster.local  subsets:  - name: target-egress-gateway-mTLS  trafficPolicy:  tls:  mode: ISTIO_MUTUAL EOF 

3. Create a ServiceEntry in the egress namespace to explicitly register example.com in the mesh's service registry for the team-x namespace:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: ServiceEntry metadata:  name: example-com-ext  namespace: istio-egress  labels:  # Show this service and its telemetry in the Cloud Service Mesh page of the Google Cloud console  service.istio.io/canonical-name: example.com spec:  hosts:  - example.com  ports:  - number: 80  name: http  protocol: HTTP  - number: 443  name: tls  protocol: TLS  resolution: DNS  location: MESH_EXTERNAL  exportTo:  - 'team-x'  - 'istio-egress' EOF 

4. Create a VirtualService to route traffic to example.com through the egress gateway. There are two match conditions: the first condition directs traffic to the egress gateway, and the second directs traffic from the egress gateway to the destination host. The exportTo property controls which namespaces can use the virtual service.

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata:  name: example-com-through-egress-gateway  namespace: istio-egress spec:  hosts:  - example.com  gateways:  - istio-egress/egress-gateway  - mesh  http:  - match:  - gateways:  - mesh  port: 80  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-mTLS  port:  number: 80  weight: 100  - match:  - gateways:  - istio-egress/egress-gateway  port: 80  route:  - destination:  host: example.com  port:  number: 80  weight: 100  exportTo:  - 'istio-egress'  - 'team-x' EOF 

5. Run istioctl analyze to check for configuration errors:

   ${ISTIOCTL} analyze -n istio-egress --revision REVISION 

   The output is similar to the following:

   ✔ No validation issues found when analyzing namespace: istio-egress. 

6. Send several requests through the egress gateway to the external site:

   for i in {1..4} do  kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- \  curl -s -o /dev/null -w "%{http_code}\n" http://example.com done 

   You see 200 status codes for all four responses.

7. Verify that the requests were directed through the egress gateway by checking the proxy access logs. First check the access log for the proxy sidecar deployed with the test application:

   kubectl -n team-x logs -f $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) istio-proxy 

   For each request you send, you see a log entry similar to the following:

   [2020-09-14T17:37:08.045Z] "HEAD / HTTP/1.1" 200 - "-" "-" 0 0 5 4 "-" "curl/7.67.0" "d57ea5ad-90e9-46d9-8b55-8e6e404a8f9b" "example.com" "10.1.4.12:8080" outbound|80||istio-egressgateway.istio-egress.svc.cluster.local 10.1.0.17:42140 93.184.216.34:80 10.1.0.17:60326 - - 

8. Also check the egress gateway access log:

   kubectl -n istio-egress logs -f $(kubectl -n istio-egress get pod -l istio=egressgateway \  -o jsonpath="{.items[0].metadata.name}") istio-proxy 

   For each request you send, you see an egress gateway access log entry similar to the following:

   [2020-09-14T17:37:08.045Z] "HEAD / HTTP/2" 200 - "-" "-" 0 0 4 3 "10.1.0.17" "curl/7.67.0" "095711e6-64ef-4de0-983e-59158e3c55e7" "example.com" "93.184.216.34:80" outbound|80||example.com 10.1.4.12:37636 10.1.4.12:8080 10.1.0.17:44404 outbound_.80_.target-egress-gateway-mTLS_.istio-egressgateway.istio-egress.svc.cluster.local - 

Configure different routing for a second namespace

Configure routing for a second external host to learn how different external connectivity can be configured for different teams.

1. Create a Sidecar resource for the team-y namespace:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: Sidecar metadata:  name: default  namespace: team-y spec:  outboundTrafficPolicy:  mode: REGISTRY_ONLY  egress:  - hosts:  - 'istio-egress/*'  - 'team-y/*' EOF 

2. Deploy the test application to the team-y namespace:

   kubectl -n team-y create -f ./test.yaml 

3. Register a second external host and export it to the team-x and the team-y namespace:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: ServiceEntry metadata:  name: httpbin-org-ext  namespace: istio-egress  labels:  # Show this service and its telemetry in the Cloud Service Mesh page of the Google Cloud console  service.istio.io/canonical-name: httpbin.org spec:  hosts:  - httpbin.org  ports:  - number: 80  name: http  protocol: HTTP  - number: 443  name: tls  protocol: TLS  resolution: DNS  location: MESH_EXTERNAL  exportTo:  - 'istio-egress'  - 'team-x'  - 'team-y' EOF 

4. Create a virtual service to route traffic to httpbin.org through the egress gateway:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata:  name: httpbin-org-through-egress-gateway  namespace: istio-egress spec:  hosts:  - httpbin.org  gateways:  - istio-egress/egress-gateway  - mesh  http:  - match:  - gateways:  - mesh  port: 80  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-mTLS  port:  number: 80  weight: 100  - match:  - gateways:  - istio-egress/egress-gateway  port: 80  route:  - destination:  host: httpbin.org  port:  number: 80  weight: 100  exportTo:  - 'istio-egress'  - 'team-x'  - 'team-y' EOF 

5. Run istioctl analyze to check for configuration errors:

   ${ISTIOCTL} analyze -n istio-egress --revision REVISION 

   You see:

   ✔ No validation issues found when analyzing namespace: istio-egress. 

6. Make a request to httpbin.org from the team-y test app:

   kubectl -n team-y exec -it $(kubectl -n team-y get pod -l app=test -o \  jsonpath={.items..metadata.name}) -c test -- curl -I http://httpbin.org 

   You see a 200 OK response.

7. Also make a request to httpbin.org from the team-x test app:

   kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -I http://httpbin.org 

   You see a 200 OK response.

8. Attempt to make a request to example.com from the team-y namespace:

   kubectl -n team-y exec -it $(kubectl -n team-y get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -I http://example.com 

   The request fails because there is no outbound route configured for the example.com host.

Using Authorization Policy to provide additional control over traffic

In this tutorial, authorization policies for the egress gateway are created in the istio-egressnamespace. You can configure Kubernetes RBAC so that only network administrators can access the istio-egress namespace.

1. Create an AuthorizationPolicy so that applications in the team-x namespace can connect to example.com but not to other external hosts when sending requests using port 80. The corresponding targetPort on the egress gateway pods is 8080.

   cat <<EOF | kubectl apply -f - apiVersion: security.istio.io/v1beta1 kind: AuthorizationPolicy metadata:  name: egress-team-x-to-example-com  namespace: istio-egress spec:  action: ALLOW  rules:  - from:  - source:  namespaces:  - 'team-x'  to:  - operation:  hosts:  - 'example.com'  when:  - key: destination.port  values: ["8080"] EOF 

2. Verify that you can make a request to example.com from the test application in the team-x namespace:

   kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -I http://example.com 

   You see a 200 OK response.

3. Try to make a request to httpbin.org from the test application in the team-x namespace:

   kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -s -w " %{http_code}\n" \  http://httpbin.org 

   The request fails with an RBAC: access denied message and a 403 Forbidden status code. You may need to wait a few seconds because there is often a short delay before authorization policy takes effect.

4. Authorization policies provide rich control over which traffic is allowed or denied. Apply the following authorization policy to allow the test app in the team-y namespace to make requests to httpbin.org by using one particular URL path when sending requests using port 80. The corresponding targetPort on the egress gateway pods is 8080.

   cat <<EOF | kubectl apply -f - apiVersion: security.istio.io/v1beta1 kind: AuthorizationPolicy metadata:  name: egress-team-y-to-httpbin-teapot  namespace: istio-egress spec:  action: ALLOW  rules:  - from:  - source:  namespaces:  - 'team-y'  to:  - operation:  hosts:  - httpbin.org  paths: ['/status/418']  when:  - key: destination.port  values: ["8080"] EOF 

5. Attempt to connect to httpbin.org from the test app in the team-y namespace:

   kubectl -n team-y exec -it $(kubectl -n team-y get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -s -w " %{http_code}\n" \  http://httpbin.org 

   The request fails with an RBAC: access denied message and a 403 Forbidden status code.

6. Now make a request to httpbin.org/status/418 from the same app:

   kubectl -n team-y exec -it $(kubectl -n team-y get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl http://httpbin.org/status/418 

   The request succeeds because the path matches the pattern in the authorization policy. The output is similar to the following:

    -=[ teapot ]=- _...._ .' _ _ `. | ."` ^ `". _, \_;`"---"`|// | ;/ \_ _/ `"""` 

TLS origination at the egress gateway

You can configure egress gateways to upgrade (originate) plain HTTP requests to TLS or mutual TLS. Allowing applications to make plain HTTP requests has several advantages when used with Istio mutual TLS and TLS origination. For more information, see the best practices guide.

1. Create a DestinationRule. The DestinationRule specifies that the gateway originate a TLS connection to example.com.

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata:  name: example-com-originate-tls  namespace: istio-egress spec:  host: example.com  subsets:  - name: example-com-originate-TLS  trafficPolicy:  portLevelSettings:  - port:  number: 443  tls:  mode: SIMPLE  sni: example.com EOF 

2. Update the virtual service for example.com so that requests to port 80 on the gateway are upgraded to TLS on port 443 when they are sent to the destination host:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata:  name: example-com-through-egress-gateway  namespace: istio-egress spec:  hosts:  - example.com  gateways:  - mesh  - istio-egress/egress-gateway  http:  - match:  - gateways:  - mesh  port: 80  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-mTLS  port:  number: 80  - match:  - gateways:  - istio-egress/egress-gateway  port: 80  route:  - destination:  host: example.com  port:  number: 443  subset: example-com-originate-TLS  weight: 100 EOF 

3. Make several requests to example.com from the test app in the team-x namespace:

   for i in {1..4} do  kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -I http://example.com done 

   As before, the requests succeed with 200 OK responses.

4. Check the egress gateway log to verify that the gateway routed the requests to the destination host by originating TLS connections:

   kubectl -n istio-egress logs -f $(kubectl -n istio-egress get pod -l istio=egressgateway \  -o jsonpath=" {.items[0].metadata.name}") istio-proxy 

   The output is similar to the following:

   [2020-09-24T17:58:02.548Z] "HEAD / HTTP/2" 200 - "-" "-" 0 0 6 5 "10.1.1.15" "curl/7.67.0" "83a77acb-d994-424d-83da-dd8eac902dc8" "example.com" "93.184.216.34:443" outbound|443|example-com-originate-TLS|example.com 10.1.4.31:49866 10.1.4.31:8080 10.1.1.15:37334 outbound_.80_.target-egress-gateway-mTLS_.istio-egressgateway.istio-egress.svc.cluster.local - 

   The proxy sidecar sent the request to the gateway using port 80 and TLS originated on port 443 to send the request to the destination host.

Pass-through of HTTPS/TLS connections

Your existing applications might already be using TLS connections when communicating with external services. You can configure the egress gateway to pass TLS connections through without decrypting them.

1. Modify your configuration so that the egress gateway uses TLS pass-through for connections to port 443:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: Gateway metadata:  name: egress-gateway  namespace: istio-egress spec:  selector:  istio: egressgateway  servers:  - port:  number: 80  name: https  protocol: HTTPS  hosts:  - '*'  tls:  mode: ISTIO_MUTUAL  - port:  number: 443  name: tls  protocol: TLS  hosts:  - '*'  tls:  mode: PASSTHROUGH EOF 

2. Update the DestinationRule pointing to the egress gateway to add a second subset for port 443 on the gateway. This new subset doesn't use mutual TLS. Istio mutual TLS is not supported for pass-through of TLS connections. Connections on port 80 still use mTLS:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1alpha3 kind: DestinationRule metadata:  name: target-egress-gateway  namespace: istio-egress spec:  host: istio-egressgateway.istio-egress.svc.cluster.local  subsets:  - name: target-egress-gateway-mTLS  trafficPolicy:  portLevelSettings:  - port:  number: 80  tls:  mode: ISTIO_MUTUAL  - name: target-egress-gateway-TLS-passthrough EOF 

3. Update the virtual service for example.com so that TLS traffic on port 443 is passed through the gateway:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata:  name: example-com-through-egress-gateway  namespace: istio-egress spec:  hosts:  - example.com  gateways:  - mesh  - istio-egress/egress-gateway  http:  - match:  - gateways:  - mesh  port: 80  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-mTLS  port:  number: 80  - match:  - gateways:  - istio-egress/egress-gateway  port: 80  route:  - destination:  host: example.com  port:  number: 443  subset: example-com-originate-TLS  weight: 100  tls:  - match:  - gateways:  - mesh  port: 443  sniHosts:  - example.com  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-TLS-passthrough  port:  number: 443  - match:  - gateways:  - istio-egress/egress-gateway  port: 443  sniHosts:  - example.com  route:  - destination:  host: example.com  port:  number: 443  weight: 100  exportTo:  - 'istio-egress'  - 'team-x' EOF 

4. Update the virtual service for httpbin.org so that TLS traffic on port 443 is passed through the gateway:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata:  name: httpbin-org-through-egress-gateway  namespace: istio-egress spec:  hosts:  - httpbin.org  gateways:  - istio-egress/egress-gateway  - mesh  http:  - match:  - gateways:  - mesh  port: 80  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-mTLS  port:  number: 80  weight: 100  - match:  - gateways:  - istio-egress/egress-gateway  port: 80  route:  - destination:  host: httpbin.org  port:  number: 80  weight: 100  tls:  - match:  - gateways:  - mesh  port: 443  sniHosts:  - httpbin.org  route:  - destination:  host: istio-egressgateway.istio-egress.svc.cluster.local  subset: target-egress-gateway-TLS-passthrough  port:  number: 443  - match:  - gateways:  - istio-egress/egress-gateway  port: 443  sniHosts:  - httpbin.org  route:  - destination:  host: httpbin.org  port:  number: 443  weight: 100  exportTo:  - 'istio-egress'  - 'team-x'  - 'team-y' EOF 

5. Add an authorization policy that accepts any kind of traffic sent to port 443 of the egress gateway service. The corresponding targetPort on the gateway pods is 8443.

   cat <<EOF | kubectl apply -f - apiVersion: security.istio.io/v1beta1 kind: AuthorizationPolicy metadata:  name: egress-all-443  namespace: istio-egress spec:  action: ALLOW  rules:  - when:  - key: destination.port  values: ["8443"] EOF 

6. Run istioctl analyze to check for configuration errors:

   ${ISTIOCTL} analyze -n istio-egress --revision REVISION 

   You see:

   ✔ No validation issues found when analyzing namespace: istio-egress. 

7. Make a plain HTTP request to example.com from the test application in the team-xnamespace:

   kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -I http://example.com 

   The request succeeds with a 200 OK response.

8. Now make several TLS (HTTPS) requests from the test application in the team-x namespace:

   for i in {1..4} do  kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -s -o /dev/null \  -w "%{http_code}\n" \  https://example.com done 

   You see 200 responses.

9. Look at the egress gateway log again:

   kubectl -n istio-egress logs -f $(kubectl -n istio-egress get pod -l istio=egressgateway \  -o jsonpath="{.items[0].metadata.name}") istio-proxy 

   You see log entries similar to the following:

   [2020-09-24T18:04:38.608Z] "- - -" 0 - "-" "-" 1363 5539 10 - "-" "-" "-" "-" "93.184.216.34:443" outbound|443||example.com 10.1.4.31:51098 10.1.4.31:8443 10.1.1.15:57030 example.com - 

   The HTTPS request has been treated as TCP traffic and passed through the gateway to the destination host, so no HTTP information is included in the log.

Using Kubernetes NetworkPolicy as an additional control

There are many scenarios in which an application can bypass a sidecar proxy. You can use Kubernetes NetworkPolicy to additionally specify which connections workloads are allowed to make. After a single network policy is applied, all connections that aren't specifically allowed are denied.

This tutorial only considers egress connections and egress selectors for network policies. If you control ingress with network policies on your own clusters, then you must create ingress policies to correspond to your egress policies. For example, if you allow egress from workloads in the team-x namespace to the team-y namespace, you must also allow ingress to the team-y namespace from the team-x namespace.

1. Allow workloads and proxies deployed in the team-x namespace to connect to istiod and the egress gateway:

   cat <<EOF | kubectl apply -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata:  name: allow-egress-to-control-plane  namespace: team-x spec:  podSelector: {}  policyTypes:  - Egress  egress:  - to:  - namespaceSelector:  matchLabels:  "kubernetes.io/metadata.name": istio-system  podSelector:  matchLabels:  istio: istiod  - namespaceSelector:  matchLabels:  "kubernetes.io/metadata.name": istio-egress  podSelector:  matchLabels:  istio: egressgateway EOF 

2. Allow workloads and proxies to query DNS:

   cat <<EOF | kubectl apply -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata:  name: allow-egress-to-dns  namespace: team-x spec:  podSelector: {}  policyTypes:  - Egress  egress:  - to:  - namespaceSelector:  matchLabels:  "kubernetes.io/metadata.name": kube-system  ports:  - port: 53  protocol: UDP  - port: 53  protocol: TCP EOF 

3. Allow workloads and proxies to connect to the IPs that serve Google APIs and services, including Cloud Service Mesh certificate authority:

   cat <<EOF | kubectl apply -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata:  name: allow-egress-to-google-apis  namespace: team-x spec:  podSelector: {}  policyTypes:  - Egress  egress:  - to:  - ipBlock:  cidr: 199.36.153.4/30  - ipBlock:  cidr: 199.36.153.8/30 EOF 

4. Allow workloads and proxies to connect to the GKE metadata server:

   cat <<EOF | kubectl apply -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata:  name: allow-egress-to-metadata-server  namespace: team-x spec:  podSelector: {}  policyTypes:  - Egress  egress:  - to: # For GKE data plane v2  - ipBlock:  cidr: 169.254.169.254/32  - to: # For GKE data plane v1  - ipBlock:  cidr: 127.0.0.1/32 # Prior to 1.21.0-gke.1000  - ipBlock:  cidr: 169.254.169.252/32 # 1.21.0-gke.1000 and later  ports:  - protocol: TCP  port: 987  - protocol: TCP  port: 988 EOF 

5. Optional: Allow workloads and proxies in the team-x namespace to make connections to each other:

   cat <<EOF | kubectl apply -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata:  name: allow-egress-to-same-namespace  namespace: team-x spec:  podSelector: {}  ingress:  - from:  - podSelector: {}  egress:  - to:  - podSelector: {} EOF 

6. Optional: Allow workloads and proxies in the team-x namespace to make connections to workloads deployed by a different team:

   cat <<EOF | kubectl apply -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata:  name: allow-egress-to-team-y  namespace: team-x spec:  podSelector: {}  policyTypes:  - Egress  egress:  - to:  - namespaceSelector:  matchLabels:  "kubernetes.io/metadata.name": team-y EOF 

7. Connections between sidecar proxies persist. Existing connections are not closed when you apply a new network policy. Restart the workloads in the team-x namespace to make sure existing connections are closed:

   kubectl -n team-x rollout restart deployment 

8. Verify that you can still make an HTTP request to example.com from the test application in the team-xnamespace:

   kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- curl -I http://example.com 

   The request succeeds with a 200 OK response.

Directly accessing Google APIs using Private Google Access and IAM permissions

Google's APIs and services are exposed using external IP addresses. When pods with VPC-native alias IP addresses make connections to Google APIs by using Private Google Access, the traffic never leaves Google's network.

When you set up the infrastructure for this tutorial, you enabled Private Google Access for the subnet used by GKE pods. To allow access to the IP addresses used by Private Google Access, you created a route, a VPC firewall rule, and a private DNS zone. This configuration lets pods reach Google APIs directly without sending traffic through the egress gateway. You can control which APIs are available to specific Kubernetes service accounts (and hence namespaces) by using Workload Identity Federation for GKE and IAM. Istio authorization doesn't take effect because the egress gateway is not handling connections to the Google APIs.

Before pods can call Google APIs, you must use IAM to grant permissions. The cluster you are using for this tutorial is configured to use Workload Identity Federation for GKE, which allows a Kubernetes service account to act as a Google service account.

1. Create a Google service account for your application to use:

   gcloud iam service-accounts create sa-test-app-team-x 

2. Allow the Kubernetes service account to impersonate the Google service account:

   gcloud iam service-accounts add-iam-policy-binding \  --role roles/iam.workloadIdentityUser \  --member "serviceAccount:${PROJECT_ID}.svc.id.goog[team-x/test]" \  sa-test-app-team-x@${PROJECT_ID}.iam.gserviceaccount.com 

3. Annotate the Kubernetes service account for the test app in the team-x namespace with the email address of the Google service account:

   cat <<EOF | kubectl apply -f - apiVersion: v1 kind: ServiceAccount metadata:  annotations:  iam.gke.io/gcp-service-account: sa-test-app-team-x@${PROJECT_ID}.iam.gserviceaccount.com  name: test  namespace: team-x EOF 

4. The test application pod must be able to access the Google metadata server (running as a DaemonSet) to obtain temporary credentials for calling Google APIs. Create a service entry for the GKE metadata server:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: ServiceEntry metadata:  name: metadata-google-internal  namespace: istio-egress  labels:  # Show this service and its telemetry in the Cloud Service Mesh page of the Google Cloud console  service.istio.io/canonical-name: metadata.google.internal spec:  hosts:  - metadata.google.internal  ports:  - number: 80  name: http  protocol: HTTP  - number: 443  name: tls  protocol: TLS  resolution: DNS  location: MESH_EXTERNAL  exportTo:  - 'istio-egress'  - 'team-x' EOF 

5. Also create a service entry for private.googleapis.com and storage.googleapis.com:

   cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1beta1 kind: ServiceEntry metadata:  name: private-googleapis-com  namespace: istio-egress  labels:  # Show this service and its telemetry in the Cloud Service Mesh page of the Google Cloud console  service.istio.io/canonical-name: googleapis.com spec:  hosts:  - private.googleapis.com  - storage.googleapis.com  ports:  - number: 80  name: http  protocol: HTTP  - number: 443  name: tls  protocol: TLS  resolution: DNS  location: MESH_EXTERNAL  exportTo:  - 'istio-egress'  - 'team-x' EOF 

6. Verify that the Kubernetes service account is correctly configured to act as the Google service account:

   kubectl -n team-x exec -it $(kubectl -n team-x get pod -l app=test \  -o jsonpath={.items..metadata.name}) -c test -- gcloud auth list 

   You see the Google service account listed as the active and only identity.

7. Create a test file in a Cloud Storage bucket:

   echo "Hello, World!" > /tmp/hello gcloud storage buckets create gs://${PROJECT_ID}-bucket gcloud storage cp /tmp/hello gs://${PROJECT_ID}-bucket/ 

8. Grant permission for the service account to list and view files in the bucket:

   gcloud storage buckets add-iam-policy-binding gs://${PROJECT_ID}-bucket/ \  --member=serviceAccount:sa-test-app-team-x@${PROJECT_ID}.iam.gserviceaccount.com \  --role=roles/storage.objectViewer 

9. Verify that the test application can access the test bucket:

   kubectl -n team-x exec -it \ $(kubectl -n team-x get pod -l app=test -o jsonpath={.items..metadata.name}) \ -c test \ -- gcloud storage cat gs://${PROJECT_ID}-bucket/hello 

   You see:

   Hello, World!