Overview

This is the base layer for all CAAS reactive Charms. It provides all of the standard Juju hooks and starts the reactive framework when these hooks get executed.

Usage

Any CAAS or Kubernetes charm should include this in its layer.yaml. It is also recommended to include layer:docker-resource:

includes:
  - 'layer:caas-base'
  - 'layer:docker-resource'

The charm can then define its container image as a resource in metadata.yaml:

name: my-charm
resources:
  my-image:
    description: 'Image for this charm'
    type: oci-image
    auto-fetch: true

When ready, the charm should call pod_spec_set with the relevant data structure:

from charmhelpers.core import hookenv
from charms.reactive import set_flag, when, when_not

from charms import layer

@when('layer.docker-resource.my-image.available')
@when_not('charm.my-charm.started')
def create_container():
    layer.status.maintenance('configuring container')

    image_info = layer.docker_resource.get_info('my-image')
    config = hookenv.config()

    success = layer.caas_base.pod_spec_set({
        'containers': [
            {
                'name': 'my-charm',
                'imageDetails': {
                    'imagePath': image_info.registry_path,
                    'username': image_info.username,
                    'password': image_info.password,
                },
                'ports': [
                    {
                        'name': 'service',
                        'containerPort': 80,
                    },
                ],
                'config': {
                    'SOME_VALUE': config['some-option'],
                },
                'files': [
                    {
                        'name': 'configs',
                        'mountPath': '/etc/config',
                        'files': {
                            'my-charm.conf': Path('files/my-charm.conf').read_text(),
                        },
                    },
                ],
            },
        ],
    })
    if success:
        layer.status.maintenance('creating container')
        set_flag('charm.my-charm.started')
    else:
        layer.status.blocked('k8s spec failed to deploy')