microservices/

README

Example: µSvcs with Skaffold

In this example:

• Deploy multiple applications with skaffold
• In development, only rebuild and redeploy the artifacts that have changed
• Deploy multiple applications outside the working directory
• Define dependencies between artifacts

In the real world, Kubernetes deployments will consist of multiple applications that work together. In this example, we'll walk through using skaffold to develop and deploy two applications, an exposed "web" frontend which calls an unexposed "app" backend.

WARNING: If you're running this on a cloud cluster, this example will create a service and expose a webserver. It's highly suggested that you only run this example on a local, private cluster like minikube or Kubernetes in Docker for Desktop.

Running the example on minikube

From this directory, run

skaffold dev

Now, in a different terminal, hit the leeroy-web endpoint

$ curl $(minikube service leeroy-web --url)
leeroooooy app!

Now, let's change the message in leeroy-app without changing leeroy-web. Add a few exclamations points because this is exhilarating stuff.

In leeroy-app/app.go, change the message here

func handler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "leeroooooy app!!!\n")
}

Once you see the log message

[leeroy-app-5b4dfdcbc6-6vf6r leeroy-app] 2018/03/30 06:28:47 leeroy app server ready

Your service will be ready to hit again with

$ curl $(minikube service leeroy-web --url)
leeroooooy app!!!

Configuration walkthrough

Let's walk through the first part of the skaffold.yaml

artifacts:
  - image: leeroy-web
    context: leeroy-web
    requires:
     - image: base
       alias: BASE
  - image: leeroy-app
    context: leeroy-app
    requires:
      - image: base
        alias: BASE
  - image: base
    context: base

We're deploying a leeroy-web image, which we build in the context of its subdirectory and a leeroy-app image built similarly. Both of these artifacts depend on the base artifact which their Dockerfiles can reference as a build argument keyed on the alias BASE.

ARG BASE
...
FROM $BASE
COPY --from=builder /app .

leeroy-web will listen for requests, and then make a simple HTTP call to leeroy-app using Kubernetes service discovery and return that result.

In the deploy stanza, we use the glob matching pattern to deploy all YAML and JSON files in the respective Kubernetes manifest directories.

deploy:
  kubectl:
    manifests:
    - ./leeroy-web/kubernetes/*
    - ./leeroy-app/kubernetes/*