11-autobuild.md

Automatic Build

In the previous lab, we built and pushed a container image to Docker Hub manually. But it doesn't have to be manual. You can actually configure your Knative Service to automatically build when there's a change.

There's Orchestrating a source-to-URL deployment on Kubernetes tutorial in Knative docs that explains how to do this and more but we will go through the steps here as well.

Make sure you already registered a Secret for Docker Hub and created a ServiceAccount as explained in the previous lab.

Kaniko Build Template

We'll use the Kaniko Build Template in the service definition.

Install Kaniko Build Template:

kubectl apply -f https://raw.githubusercontent.com/knative/build-templates/master/kaniko/kaniko.yaml

Check that it is installed:

kubectl get buildtemplate
NAME      AGE
kaniko    24m

Define the service with inline Build

Let's now define a Knative Service that uses an inline Build,

Create a service-autobuild-docker.yaml file:

apiVersion: serving.knative.dev/v1alpha1
kind: Service
metadata:
  name: helloworld-csharp-from-source
  namespace: default
spec:
  runLatest:
    configuration:
      build:
        apiVersion: build.knative.dev/v1alpha1
        kind: Build
        spec:
          serviceAccountName: build-bot
          source:
            git:
              url: https://github.com/meteatamel/knative-tutorial.git
              revision: master
            subPath: "serving/helloworld-csharp/"
          template:
            name: kaniko
            arguments:
              - name: IMAGE
                # Replace {username} with your actual DockerHub
                value: docker.io/{username}/helloworld-csharp:from-source
      revisionTemplate:
        spec:
          container:
            # Replace {username} with your actual DockerHub
            image: docker.io/{username}/helloworld-csharp:from-source
            imagePullPolicy: Always
            env:
              - name: TARGET
                value: "C# Sample from-source"

Note the inline build section where we tell Knative Build how to get the source and how to build and push the image using Kaniko.

Run and watch the build

You can deploy the service with:

kubectl apply -f service-autobuild-docker.yaml

You should see that a build is created:

kubectl get build
NAME                                  AGE
helloworld-csharp-from-source-00001   12s

Soon after, you'll see a pod created for the build:

kubectl get pods
NAME                                              READY     STATUS     
helloworld-csharp-from-source-00001-pod-3dfef7    0/1       Init:2/3

When the build is finished, you'll see the pod in Completed state:

kubectl get pods
NAME                                              READY     STATUS 
helloworld-csharp-from-source-00001-pod-3dfef7    0/1       Completed

Soon after, you should also see a new pod created for the Knative service:

NAME                                                             READY     STATUS
helloworld-csharp-from-source-00001-deployment-5b74c5c8b-w8nmw   3/3       Running

At this point, you should see the image pushed to Docker Hub:

Test the service

We can finally test the service with curl and see that the new service is up and running:

curl http://helloworld-csharp-from-source.default.$KNATIVE_INGRESS.nip.io
Hello C# Sample from-source

What's Next?