Running a CloudRun or docker image in a mesh environment

Cloud Run ASM is an experimental feature which isn't officially supported. We do not recommend using this feature in production at this stage.

This repository implements a small launcher that prepares a mesh environment and starts the user application.

Overview

In K8s, the mesh implementation relies on a mutating webhook that patches the Pod, injecting for required environment. Docker and CloudRun images do not have an injector so this application plays that role, using the K8s and GCP APIs to setup iptables and the sidecar process or the proxyless bootstrap.

This supports running an app:

• in an Istio-like environment with a Sidecar and iptables interception
• if iptables is not available (gVisor, regular docker, dev machine), configure 'whitebox' mode ( HTTP_PROXY and localhost port forwarding for TCP)
• in proxyless gRPC mode for applications that natively support XDS and mesh, without iptables or sidecar.

The launcher is responsible for:

• discovering a GKE/K8s cluster based on environment (metadata server, env variables), and getting credentials and config
• discovering the XDS address and config (root certificates, metadata)
• setting up iptables ( equivalent to the init container or CNI in K8s ), or configuring 'whitebox' mode if lacking permissions for iptables.
• launching envoy sidecar (optional for proxyless)
• configuring pilot-agent to intercept DNS
• launching the application after the network setup is stable
• creating any necessary tunnels to allow use of mTLS, based on the HBONE (tunneling over HTTP/2) proposal in Istio. For example in CloudRun each received mTLS connection is tunnelled as a HTTP/2 stream.

The repository also includes a specialised SNI-routing gateway and controller that allows any mesh node using mTLS to tunnel requests to CloudRun with the expected authentication.

The user application will use the sidecar and XDS server to discover and communicate with other mesh workloads running in Pods, VMs or other mesh-enabled CloudRun services.

The code is based on the Istio VM startup script and injection template and will need to be kept in sync with future changes in the mesh startup.

Architecture

Before you begin

Set the common environment variables used in this document:

export PROJECT_ID=wlhe-cr
export CLUSTER_LOCATION=us-central1-c
export CLUSTER_NAME=asm-cr
# CloudRun region 
export REGION=us-central1

export WORKLOAD_NAMESPACE=fortio # Namespace where the CloudRun service will 'attach'
export WORKLOAD_NAME=cloudrun

# Name of the service account running the CloudRun service. It is recommended to use a dedicated SA for each K8s namespace
# and keep permissions as small as possible. 
# By default the namespace is extracted from the GSA name - if using a different SA or naming, WORKLOAD_NAMESPACE env
# is required when deploying the docker image. 
# (This may change as we polish the UX)
export CLOUDRUN_SERVICE_ACCOUNT=k8s-${WORKLOAD_NAMESPACE}@${PROJECT_ID}.iam.gserviceaccount.com

# Name for the cloudrun service - will use the same as the workload.
# Note that the service must be unique for region, if you want the same name in multiple namespace you must 
# use explicit config for WORKLOAD_NAME when deploying and unique cloudrun service name
export CLOUDRUN_SERVICE=${WORKLOAD_NAME}

Install

Requirements:

• For each region, you need a Serverless connector, using the same network as the GKE cluster(s) and VMs. CloudRun will use it to communicate with the Pods/VMs.
• All config clusters must have equivalent configuration - the CloudRun instance will attempt to connect to a cluster in same region but may fallback to other regions.
• You must have admin permissions for the project and cluster during the initial setup.
• Required binaries include:
  • kubectl
  • gcloud
  • envsubst

Cluster setup (once per cluster)

1. If you don't already have a cluster with managed ASM, follow Install docs. Also supported is in-cluster ASM.

2. Configure the in-cluster 'mesh connector' gateway and permissions. (this step is temporary, WIP to upstream it to Istiod and the East-West gateway. Versions of Istio after upstreaming will not need this step.)

   kubectl apply -k github.com/GoogleCloudPlatform/cloud-run-mesh/manifests/

Notes:

• In-cluster ASM with -ca mesh-ca is not , but managed ASM is. You can use managed ASM by applying the --managed flag instead.
• OSS Istio requires additional setup steps, will be documented separately.

Serverless connector setup (once per project / region / VPC network)

For each region where GKE and CloudRun will be used, install CloudRun connector. Using the Cloud Console is usually easier. However, it requires you to specify a /28 range. You can call the connector 'serverlesscon'. You will use this name to deploy the CloudRun service.

If you already have a connector, you can continue to use it and adjust the '--vpc-connector' parameter on the deploy command.

The connector MUST be on the same VPC network with the GKE cluster and configured with a not-in-use CIDR range.

Namespace Setup

After installing you can only configure new services for namespaces using namespace-level permissions in K8s. We recommend using a dedicated Google Service Account for each namespace. This requires IAM permissions to setup (once per namespace).

The Google Service Account running the CloudRun service will be mapped to a K8s namespace. Currently the 'default' K8s service account in the namespace is used - custom setup will be documented separately.

You must grant the service account used by CloudRun access to the GKE APIserver with minimal permissions.

A user or service account with namespace permissions in K8s can run these steps. It does not require K8s cluster admin permissions, but it does require IAM permissions on the project running the CloudRun service.

1. Make sure you're using the current config cluster

   gcloud container clusters get-credentials ${CLUSTER_NAME} --zone ${CLUSTER_LOCATION} --project ${PROJECT_ID}

2. Create a Google service account for the CloudRun app using the pattern: k8s-NAMESPACE ( custom names are also possible, but require extra manual configuration )

   gcloud --project ${PROJECT_ID} iam service-accounts create k8s-${WORKLOAD_NAMESPACE} \
         --display-name "Service account with access to ${WORKLOAD_NAMESPACE} k8s namespace"

3. Grant '--role="roles/container.clusterViewer"' to the service account. This allows it to view the list of GKE clusters and connect with minimal permissions ('authenticated' RBAC group)

   gcloud --project ${PROJECT_ID} projects add-iam-policy-binding \
               ${PROJECT_ID} \
               --member="serviceAccount:${CLOUDRUN_SERVICE_ACCOUNT}" \
               --role="roles/container.clusterViewer"

4. Grant additional RBAC permissions to the google service account, allowing it to access in-namespace config map and use TokenReview for the default KSA. (this step is also temporary, WIP to make it optional). This is used to get the MeshCA certificate and communicate with the managed control plane - Istio injector is mounting the equivalent tokens. If the app is using K8s, you should grant the required permissions to the mapped K8s service account ('default') - at runtime the container is configured similarly to a Pod running as that KSA.

5. Make sure the namespace is created:

   kubectl create ns ${WORKLOAD_NAMESPACE} | true

6. Associate the Google Service Account with the K8s Namespace:

   curl https://raw.githubusercontent.com/GoogleCloudPlatform/cloud-run-mesh/main/manifests/google-service-account-template.yaml | envsubst | kubectl apply -f -

Build a mesh-enabled docker image for the app

Mesh-enabled images include the sidecar (envoy), launcher and the actual application. The easiest way to create one is using a 'golden image', that is used as base.

The samples/fortio/Dockerfile directory contains an example Dockerfile or you can use the pre-built image gcr.io/wlhe-cr/fortio-mesh:main

To build your own image, use the Dockerfile as an example:

git clone https://github.com/GoogleCloudPlatform/cloud-run-mesh.git
cd cloud-run-mesh

# Base image. You can create a custom 'golden' base, starting with ASM proxy image and adding the 
# startup helper (krun) and other files or configs you need. This doc uses the image
# used for the CI/CD testing.
export GOLDEN_IMAGE=gcr.io/wlhe-cr/krun:main

# Target image 
export IMAGE=gcr.io/${PROJECT_ID}/fortio-mesh:main

(cd samples/fortio && docker build . -t ${IMAGE} --build-arg=BASE=${GOLDEN_IMAGE} )

docker push ${IMAGE}

Deploy the image to CloudRun

Deploy the service, with explicit configuration:

# If you didn't build a custom docker image, you can use the prebuilt image: 
# IMAGE=gcr.io/wlhe-cr/fortio-mesh:main

gcloud alpha run deploy ${CLOUDRUN_SERVICE} \
          --platform managed \
          --project ${PROJECT_ID} \
          --region ${REGION} \
          --execution-environment=gen2 \
          --service-account=k8s-${WORKLOAD_NAMESPACE}@${PROJECT_ID}.iam.gserviceaccount.com \
          --allow-unauthenticated \
          --use-http2 \
          --port 15009 \
          --image ${IMAGE} \
          --vpc-connector projects/${PROJECT_ID}/locations/${REGION}/connectors/serverlesscon \
         --set-env-vars="CLUSTER_NAME=${CLUSTER_NAME}" \
         --set-env-vars="CLUSTER_LOCATION=${CLUSTER_LOCATION}"

For versions of gcloud older than 353.0, replace --execution-environment=gen2 with --sandbox=minivm.

Note that CLUSTER_NAME and CLUSTER_LOCATION are optional because krun picks a config cluster in the same region that is setup with MCP and fallbacks to another config cluster if the local cluster is unavailable. Cluster names starting with 'istio' will be used first in a region. (Will likely change to use a dedicated label on the project - WIP)

• gcloud run deploy SERVICE --platform=managed --project --region is common required parameters
• --execution-environment=gen2 is currently required to have iptables enabled. Without it the 'whitebox' mode will be used (still WIP)
• --service-account is recommended for 'minimal privilege'. The service account will act as a K8s SA, and have its RBAC permissions
• --use-http2 and --port 15009 are required

Configure the CloudRun service in K8s

For workloads in K8s to communicate with the CloudRun service you must create a few Istio configurations.

This step will be replaced by auto-registration (WIP), but is currently required:

export SNI_GATE_IP=$(kubectl -n istio-system get service internal-hgate -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
export K_SERVICE=$(gcloud run services describe ${CLOUDRUN_SERVICE} --region ${REGION} --project ${PROJECT_ID} --format="value(status.address.url)" | sed s,https://,, | sed s/.a.run.app// )

curl https://raw.githubusercontent.com/GoogleCloudPlatform/cloud-run-mesh/main/manifests/sni-service-template.yaml | SNI_GATE_IP=${SNI_GATE_IP} K_SERVICE=${K_SERVICE} envsubst  | kubectl apply -f -

# Or: cat ../../manifests/sni-service-template.yaml | SNI_GATE_IP=${SNI_GATE_IP} K_SERVICE=${K_SERVICE} envsubst  | kubectl apply -f -

This creates a K8s Service with the same base name as the cloudrun service (for example: fortio-cr-icq63pqnqq-uc). You can use VirtualService or K8s Gateway API to aggregate routing and use custom names.

Testing

1. Deploy an in-cluster application. The CloudRun service will connect to it:

   gcloud container clusters get-credentials ${CLUSTER_NAME} --zone ${CLUSTER_LOCATION} --project ${PROJECT_ID}
   
   kubectl create ns fortio
   kubectl label namespace fortio  istio.io/rev=asm-managed 
   kubectl -n fortio apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/cloud-run-mesh/main/samples/fortio/in-cluster.yaml

2. Use the CloudRun service to connect to the in-cluster workload. Use the CR service URL with /fortio/ path to access the UI of the app.

   In the UI, use "http://fortio.fortio.svc:8080" and you should see the results for testing the connection to the in-cluster app.

In general, the CloudRun applications can use any K8s service name, including shorter version for same-namespace services. So fortio, fortio.fortio, fortio.fortio.svc.cluster.local also work.

In this example the in-cluster application is using ASM. It is also possible to access regular K8s applications without a sidecar.

3. To verify calls from K8s to CloudRun, you can use 'kubectl exec' to the fortio Pod, with a command like

  curl http://${KSERVICE}.fortio.svc:8080/fortio/ 

or

  fortio load http://${KSERVICE}.fortio.svc:8080/echo

The cloudrun service is mapped to a K8s service with the same name. This can be used as a destination in Gateway or VirtualService using a different name or load balancing multiple CloudRun regions.

apiVersion: v1
kind: Service
metadata:
  name: myservice
  namespace: fortio
spec:
  ports:
    - port: 8080
      name: http
      targetPort: 15443
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: myservice
  namespace: fortio
spec:
  hosts:
    - myservice
    - myservice.fortio.svc
  http:
    - route:
        # Use the actual CR service.
        - destination:
            host: cloudrun-6c3hzwsnla-uc
          weight: 25
        - destination:
            host: cloudrun2-6c3hzwsnla-uc
          weight: 75

Configuration options

When running in CloudRun, default automatic configuration is based on environment variables, metadata servers, and calls to GKE APIs. For debugging (as a regular process), when running with a regular docker or to override the defaults, the settings must be explicit.

• WORKLOAD_NAMESPACE - default value extracted from the service account running the CloudRun service
• WORKLOAD_NAME - default value is the CloudRun service name. Also used as 'canonical service'.
• PROJECT_ID - default is the same project as the CloudRun service.
• CLUSTER_LOCATION - default is the same region as the CloudRun service. If CLUSTER_NAME is not specified, a cluster with ASM in the region or zone will be picked.
• CLUSTER_NAME - if not set, clusters in same region or a zone in the region will be picked. Cluster names starting with 'istio' are currently picked first. (WIP to define a labeling or other API for cluster selection)

Also for local development:

• GOOGLE_APPLICATION_CREDENTIALS must be set to a file that is mounted, containing GSA credentials.
• Alternatively, a KUBECONFIG file must be set and configured for the intended cluster.

How it works

The setup is similar to Istio on VM support.

The mesh connector is an extended version of the "East-West" Gateway, provide access to the in-cluster Istiod and handles forwarding the requests from pods to CloudRun.

The 'golden image' includes the istio sidecar components and a launcher, similar with Istio on VMs. The launcher will

1. Load the istio-system/mesh-env config map created by the connector (until it is moved to Istiod proper)
2. Set iptables interception
3. Generate the mesh certificates
4. Start envoy using pilot-agent
5. Run the application.

The application works the same as Pods or VMs with Istio support: outgoing requests are intercepted then sent to Envoy where mTLS and policies are handled.

Debugging and troubleshooting

For install, few useful commands:

kubectl -n istio-system get svc hgate -o yaml
kubectl -n istio-system get svc internal-hgate -o yaml

# Status should show the external and internal IPs of the mesh connector.

kubectl -n istio-system get cm mesh-env -o yaml

# Should include 'MESH_TENANT' if using managed ASM
# Should include root cert, external and internal IP address of the 'mesh connector'