12-dockerbuild.md

Docker Hub Build

In the previous lab, we built and pushed a container image to Google Cloud Registry (GCR). In this lab, we will push to Docker Hub instead. It's more involved as we need to register secrets for Docker Hub.

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.

Register secrets for Docker Hub

We need to first register a secret in Kubernetes for authentication with Docker Hub.

Create a docker-secret.yaml file for Secret manifest, which is used to store your Docker Hub credentials:

apiVersion: v1
kind: Secret
metadata:
  name: basic-user-pass
  annotations:
    build.knative.dev/docker-0: https://index.docker.io/v1/
type: kubernetes.io/basic-auth
data:
  # Use 'echo -n "username" | base64' to generate this string
  username: BASE64_ENCODED_USERNAME
  # Use 'echo -n "password" | base64' to generate this string
  password: BASE64_ENCODED_PASSWORD

Make sure to replace BASE64_ENCODED_USERNAME and BASE64_ENCODED_PASSWORD with your Base64 encoded DockerHub username and password.

Create a service-account.yaml for Service Account used to link the build process to the secret:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: build-bot
secrets:
  - name: basic-user-pass

Apply the Secret and Service Account:

kubectl apply -f docker-secret.yaml
secret "basic-user-pass" created
kubectl apply -f service-account.yaml
serviceaccount "build-bot" created

Design the build

We will use Kaniko again in our Build. Create a build-helloworld-docker.yaml build file:

apiVersion: build.knative.dev/v1alpha1
kind: Build
metadata:
  name: build-helloworld-docker
spec:
  serviceAccountName: build-bot
  source:
    git:
      url: https://github.com/meteatamel/knative-tutorial.git
      revision: master
    subPath: serving/helloworld/csharp
  steps:
  - name: build-and-push
    image: "gcr.io/kaniko-project/executor:v0.6.0"
    args:
    - "--dockerfile=/workspace/Dockerfile"
    # Replace {username} with your actual DockerHub
    - "--destination=docker.io/{username}/helloworld:build"

This uses Knative Build to download the source code in the 'workspace' directory and then use Kaniko to build and push an image to Docker Hub tagged with knativebuild. Note how we're using build-bot as serviceAccountName.

Run and watch the build

You can start the build with:

kubectl apply -f build-helloworld-docker.yaml

Check that it is created:

kubectl get build

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

kubectl get pods
NAME                                             READY     STATUS
build-helloworld-docker-pod-454bd8        0/1       Init:2/3

You can see the progress of the build with:

kubectl logs --follow --container=build-step-build-and-push <podid>

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

kubectl get pods
NAME                                              READY     STATUS
build-helloworld-docker-pod-454bd8         0/1       Completed

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

What's Next?

Kaniko Build Template