This is part 3 in a series of posts where I spike out a cloud microservice app on GCP. In this post I set up a Kubernetes (k8s) cluster in Google Kubernetes Engine (GKE), deploy my app and make it available as an external service.

• Part 1 - the CryptoTracker app introduces my prototype microservice app
• Part 2 - run in GCP gets the app running in Docker in Google Compute Engine
• Part 3 - run in GKE (this page) gets the app running in Google Kubernetes Engine
• Part 4 - run in an Istio service mesh gets the app running in an Istio service mesh
• Part 5 - secure the app via TLS secures the app by using TLS over HTTPS

Create a new Kubernetes cluster and deploy

Rather than exploit the full power of the kubectl command line I used the GKE UI to keep things simple. I created a basic k8s cluster with 2 small nodes in europe-west-2 (London) region, keeping everything else as default.

Once the cluster was up and running it was trivial to deploy my app: just the docker image name and mongo connection string are required and everything else can be kept as default. The only minor issue I had is that the colon character is not supported in an environment variable name, but the ASP.NET Core configuration settings copes with this. Double-underscores are supported on all environments so I just changed MongoDB:ConnectionString to MongoDB__ConnectionString and it all worked fine.

Expose my app as a k8s service

By default, any deployment is not exposed outside the GKE cluster and a service is required to give a public endpoint. When I view my deployment in the Cloud console (Kubernetes Engine -> Workloads -> ctmd) I can see a single pod running and have the option to scale it up or down. The pod itself is transient and may be replaced at any time, resulting in a new IP address. A service will have a static IP address and load balance between any number of underlying, transient, pods.

I have mapped my container port 8080 to port 80 (http default) on my service so I don’t need to specify a port in the url any more. Once the service is created I can hit the service’s external IP address and access the URL (http://<service ip>/api/v1/currencies) exposed by my app!