How to pack your hooks-based charm with Charmcraft

See also:

You want a hooks-based charm. Such a charm cannot be initialised with Charmcraft. However, it can be packed with Charmcraft. This document shows you how.

Introduced in Charmcraft 1.4

Suppose you have a hooks-only charm, for example, tiny-bash, which you can obtain as follows:

$ git clone https://github.com/erik78se/tiny-bash

To make it packable by Charmcraft, all you need to do is navigate inside the charm directory and create a charmcraft.yaml file with the part definition for a hooks-based charm, as shown below:

type: charm

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

parts:
  tiny-bash:
    plugin: dump
    source: .
    prime:
      - LICENSE
      - README.md
      - config.yaml
      - copyright
      - hooks
      - icon.svg
      - metadata.yaml

After this, you can pack your charm with charmcraft pack, as usual:

$ charmcraft pack
Charms packed:
    tiny-bash_ubuntu-20.04-amd64.charm

If successful, the result should look as below, i.e., the charm file should contain all the files listed in the prime section of the tiny-bash part and the charm manifest.

$ unzip -l tiny-bash_ubuntu-20.04-amd64.charm
Archive:  tiny-bash_ubuntu-20.04-amd64.charm
  Length      Date    Time    Name
---------  ---------- -----   ----
      423  2021-11-12 19:37   metadata.yaml
      431  2021-11-12 19:37   README.md
       12  2021-11-12 19:37   config.yaml
     3693  2021-11-12 19:37   icon.svg
       38  2021-11-12 19:37   copyright
      261  2021-11-12 20:08   manifest.yaml
    34523  2021-11-12 19:37   LICENSE
      381  2021-11-12 19:37   hooks/update-status
      346  2021-11-12 19:37   hooks/start
     1294  2021-11-12 19:37   hooks/shared-fs-relation-changed
      563  2021-11-12 19:37   hooks/stop
      497  2021-11-12 19:37   hooks/leader-elected
      447  2021-11-12 19:37   hooks/install
      417  2021-11-12 19:37   hooks/leader-settings-changed
      811  2021-11-12 19:37   hooks/upgrade-charm
      625  2021-11-12 19:37   hooks/config-changed
---------                     -------
    44762                     16 files

And you can also deploy your application with juju deploy, as usual:

$ juju deploy ./tiny-bash_ubuntu-20.04-amd64.charm
Located local charm "tiny-bash", revision 0
Deploying "tiny-bash" from local charm "tiny-bash", revision 0

If successful, the result should look as below, i.e., with the application status active.

$ juju status
Model    Controller           Cloud/Region         Version  SLA          Timestamp
default  localhost-localhost  localhost/localhost  2.9.12   unsupported  17:23:23-03:00

App        Version  Status  Scale  Charm      Store  Channel  Rev  OS      Message
tiny-bash           active      1  tiny-bash  local             0  ubuntu  update-status ran: 20:22

Unit          Workload  Agent  Machine  Public address  Ports  Message
tiny-bash/0*  active    idle   0        10.2.17.31             update-status ran: 20:22

Machine  State    DNS         Inst id        Series  AZ  Message
0        started  10.2.17.31  juju-55481c-0  focal       Running

Last updated 3 months ago.