Build image directly in Kubernetes (e.g. using Kubernetes Job)

[collimarco]

I have read the docs multiple times, but I can't find an answer.

Is there any way to build an image, using pack or similar, directly inside a Kubernetes pod / job?

Example:

apiVersion: batch/v1
kind: Job
metadata:
  name: build-app-image-with-buildpacks
spec:
  template:
    spec:
      restartPolicy: Never
      containers:
        - name: build-app-image-with-buildpacks
          image: buildpacksio/pack:latest
          command: ['build']
          args: ['<my-image> --builder <builder-image>']
          env: …

Is there any way to specify in the args that we want to download the app source code from a git repo and upload it to a docker registry?

Here's an ideal workflow:

1. Run a Job in Kubernetes
2. The Job launches a pack container passing some argments
3. The pack container automatically downloads source code from a git repo and uploads the built image to a registry

Is it possible to achieve that?

[sambhav]

@collimarco there are various k8s based platforms available.

You can use kpack or tekton

You can also directly build an image using a Job using the lifecycle. See https://github.com/tektoncd/catalog/blob/00ddee3f3d18001bf8fd22850b47239258af1d48/task/buildpacks/0.3/buildpacks.yaml#L125-L147 for eg.

[collimarco]

@samj1912 Thanks for the useful information. kpack and tekton seem more like a full CI/CD pipeline rather than a simple way to invoke the pack command.

Is there any way to use a simple K8s Job (like the one I have defined above) to invoke pack build?

If there was a git option as source code (instead of a local directory) and a Docker registry as target to save the image, then it would be possible. I think that it would be very useful to have these two options inside the pack command.

Maybe (?) in the meantime I can simply run a bash script in the container buildpacksio/pack that checkout the git repo, builds with pack and pushes with Docker...

[sambhav]

The example I gave for the lifecycle task in tekton is just an example to draw inspiration from. You can run that command inside any normal container. The main thing to look there is the lifecycle invocation and the arguments passed to the lifecycle.

[collimarco]

I have nearly found a solution:

apiVersion: batch/v1
kind: Job
metadata:
  name: buildjob
spec:
  template:
    spec:
      restartPolicy: Never
      containers:
        - name: buildjob
          image: ubuntu:latest
          command:
            - /bin/sh
            - -c
            - |
              set -e
              apt-get update
              apt-get install -y software-properties-common
              add-apt-repository ppa:cncf-buildpacks/pack-cli
              apt-get install -y pack-cli
              apt-get install -y docker.io
              apt-get install -y git
              git clone https://github.com/JetBrains/sample_rails_app.git
              cd sample_rails_app
              pack builder suggest
              pack build sample_rails_app_img --builder heroku/buildpacks:20
              echo Done

However I get an error from pack build:

ERROR: failed to build: failed to fetch builder image 'index.docker.io/heroku/buildpacks:20': Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Do you have any idea on how to solve this (we are inside a pod)?