How to change step behavior when creating a charm

See also:

• charmcraft init

Charmcraft supports the definition of a parts section in charmcraft.yaml, and that allows the charm developer to specify payloads in a very flexible way. Developers can also change the way each part step is executed by writing a scriptlet that replaces the built-in handling for that step by using override-<step> entries:

parts:
  charm:
    override-build: |
      echo "Running the build step"

This however completely replaces the original build step: in this example, the charm source will not be built. To fix that, executing the original step handler is also necessary.

To run the default processing for a step even if it’s overriden, create a new charm project with charmcraft init:

$ mkdir mycharm
$ charmcraft init
Charm operator package file and directory tree initialized.
...

Replace the contents of the new charm project’s charmcraft.yaml file with the following :

type: "charm"
bases:
  - build-on:
    - name: "ubuntu"
      channel: "20.04"
    run-on:
    - name: "ubuntu"
      channel: "20.04"

parts:
  charm:
    override-build: |
       echo "Running the build step"
       craftctl default

Run charmcraft pack to execute the parts lifecycle and package the charm. Charmcraft will run commands from the override-build scriptlet and call the default build handler for the charm plugin to create the final charm payload.