Proxy can’t access backend Cloud Run service when ingress set to internal: A Comprehensive Guide

Have you ever encountered the frustrating issue where your proxy can’t access your backend Cloud Run service when the ingress is set to internal? You’re not alone! This problem has puzzled many a developer, but fear not, dear reader, for we’re about to embark on a journey to resolve this conundrum once and for all.

Understanding the Problem

Before we dive into the solution, let’s take a step back and understand the issue at hand. When you set the ingress of your Cloud Run service to internal, it means that the service is only accessible from within the same VPC network or from other VPC networks that are peered with it. This is a great security feature, but it can cause problems when you’re trying to access your service from outside the network, such as through a proxy.

The error message you’re likely seeing is something like:

Error: Failed to connect to backend Cloud Run service: dial tcp [INTERNAL_IP]:443: i/o timeout

This error message indicates that the proxy is unable to connect to the backend Cloud Run service because it’s not accessible from outside the network.

The Solution: Using a Service Mesh

One way to solve this problem is to use a service mesh, such as Istio or Google Cloud’s Cloud Mesh. A service mesh acts as a proxy between your proxy and the backend Cloud Run service, allowing you to access the service from outside the network.

Step 1: Enable Istio on Your GKE Cluster

First, you need to enable Istio on your Google Kubernetes Engine (GKE) cluster. You can do this by running the following command:

gcloud beta container clusters update [CLUSTER_NAME] --enable-istio

Replace [CLUSTER_NAME] with the name of your GKE cluster.

Step 2: Create an Istio Gateway

Next, you need to create an Istio gateway that will act as the entry point for your proxy to access the backend Cloud Run service. Create a YAML file with the following contents:

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: [GATEWAY_NAME]
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"

Replace [GATEWAY_NAME] with the name of your gateway. Apply the YAML file to your GKE cluster using the following command:

kubectl apply -f [GATEWAY_NAME].yaml

Step 3: Create an Istio Virtual Service

Now, you need to create an Istio virtual service that will route traffic from the gateway to the backend Cloud Run service. Create a YAML file with the following contents:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: [VIRTUAL_SERVICE_NAME]
spec:
  hosts:
  - "*"
  gateways:
  - [GATEWAY_NAME]
  http:
  - route:
    - destination:
        host: [BACKEND_SERVICE_NAME].run.app
        port:
          number: 80

Replace [VIRTUAL_SERVICE_NAME] with the name of your virtual service, [GATEWAY_NAME] with the name of your gateway, and [BACKEND_SERVICE_NAME] with the name of your backend Cloud Run service. Apply the YAML file to your GKE cluster using the following command:

kubectl apply -f [VIRTUAL_SERVICE_NAME].yaml

The Solution: Using a Cloud NAT

Another way to solve this problem is to use a Cloud NAT, which allows your proxy to access the backend Cloud Run service from outside the network.

Step 1: Create a Cloud NAT

First, you need to create a Cloud NAT. You can do this by running the following command:

gcloud compute routers create [ROUTER_NAME] --region [REGION]

Replace [ROUTER_NAME] with the name of your router and [REGION] with the region of your Cloud Run service.

Step 2: Create a Cloud NAT Gateway

Next, you need to create a Cloud NAT gateway. Create a YAML file with the following contents:

apiVersion: compute.cnrm.cloud.google.com/v1beta1
kind: NATGateway
metadata:
  name: [NAT_GATEWAY_NAME]
spec:
  router: $(ref.[ROUTER_NAME].selfLink)
  natIPs:
  - $(ref.[STATIC_IP_ADDRESS].selfLink)

Replace [NAT_GATEWAY_NAME] with the name of your NAT gateway, [ROUTER_NAME] with the name of your router, and [STATIC_IP_ADDRESS] with the static IP address of your NAT gateway. Apply the YAML file to your GKE cluster using the following command:

kubectl apply -f [NAT_GATEWAY_NAME].yaml

Step 3: Configure Your Proxy

Finally, you need to configure your proxy to use the Cloud NAT gateway. Update your proxy configuration to include the following:

http:
  upstream:
    backend:
      servers:
      - [NAT_GATEWAY_IP]:80

Replace [NAT_GATEWAY_IP] with the IP address of your Cloud NAT gateway.

Comparison of Solutions

Now that we’ve explored two solutions to the problem, let’s compare them:

Solution	Advantages	Disadvantages
Service Mesh (Istio)	Provides a flexible and scalable solution Supports multiple protocols (HTTP, gRPC, etc.) Offers advanced features such as traffic management and security	Requires additional infrastructure (Istio control plane) Can be complex to set up and manage
Cloud NAT	Simpler to set up and manage Does not require additional infrastructure Supports multiple protocols (TCP, UDP, etc.)	Limited to TCP and UDP protocols Does not offer advanced features such as traffic management and security

As you can see, both solutions have their advantages and disadvantages. The service mesh solution provides a more flexible and scalable solution, but requires additional infrastructure and can be complex to set up and manage. The Cloud NAT solution is simpler to set up and manage, but is limited to TCP and UDP protocols and does not offer advanced features.

Conclusion

In conclusion, we’ve explored two solutions to the problem of accessing a backend Cloud Run service from a proxy when the ingress is set to internal. Both solutions have their advantages and disadvantages, and the choice of solution will depend on your specific use case and requirements. By following the steps outlined in this article, you should be able to resolve the issue and access your backend Cloud Run service from your proxy.

FAQs

Here are some frequently asked questions about this topic:

Q: Why can’t I access my backend Cloud Run service from my proxy when the ingress is set to internal?

A: Because the ingress is set to internal, the Cloud Run service is only accessible from within the same VPC network or from other VPC networks that are peered with it. The proxy is outside the network, so it can’t access the service.

Q: What is a service mesh?

A: A service mesh is a configurable infrastructure layer for microservices applications that makes it easy to manage service discovery, traffic management, and security.

Q: What is a Cloud NAT?

A: A Cloud NAT is a Google Cloud service that provides a highly available and scalable solution for outbound internet access from private networks.

Q: Can I use both solutions simultaneously?

A: Yes, you can use both solutions simultaneously. In fact, using a service mesh and a Cloud NAT together can provide an even more robust and scalable solution.

We hope this article has been helpful in resolving the issue of accessing a backend Cloud Run service from a proxy when the ingress is set to internal. If you have any further questions or concerns, please don’t hesitate to reach out.

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