Helpers for Juju Charms to load external resources


License
MIT
Install
pip install jujuresources==0.4.0

Documentation

Juju Resources badge

Juju Resources provides helpers for charms to load binary resources from external sources, as well as tools for creating mirrors of external resources for network-restricted deployments.

This is intended as a stop-gap until Juju has core support for resources, as well as to prototype what features are needed.

The full documentation is available online at: http://pythonhosted.org/jujuresources/

Installing

Install Juju Resources using pip:

pip install jujuresources

Charm Usage

A charm using Juju Resources will need to define a resources.yaml, such as:

resources:
    my_resource:
        url: http://example.com/path/to/my_resource.tgz
        hash: b377b7cccdd281bc5e4c4071f80e84a3
        hash_type: sha256
    my_py:
        pypi: jujuresources>=0.2
optional_resources:
    my_optional_resource:
        url: http://example.com/path/to/my_optional_resource.tgz
        hash: 476881ef4012262dfc8adc645ee786c4
        hash_type: sha256

Then, once the charm has installed Juju Resources, it can fetch and verify resources, either in Python:

from jujuresources import fetch, verify, install, config_get

if not fetch(mirror_url=config_get('resources_mirror')):
    print "Mandatory resources did not download; check resources_mirror option"
    sys.exit(1)
install('my_py')

fetch('my_optional_resource', mirror_url=config_get('resources_mirror'))
if verify('my_optional_resource'):
    install('my_optional_resource', destination='/usr/lib/myres', skip_top_level=True)

Or via the command-line / bash:

if ! juju-resources fetch -u `config-get resources_mirror`; then
    echo "Mandatory resources did not download; check resources_mirror option"
    exit 1
fi
juju-resources install my_py

juju-resources fetch -u `config-get resources_mirror` my_optional_resource
if juju-resources verify my_optional_resource; then
    juju-resources install my_optional_resource -D /usr/lib/myres -s
fi

Mirroring Resources

If you will need to deploy charms in an environment with limited network access, you can create a mirror ahead of time, or on a gateway node which has access:

mkdir local_mirror
juju-resources fetch --all -d local_mirror -r http://github.com/me/my-charm/blob/master/resources.yaml
juju-resources serve -d local_mirror

You will then have a lightweight HTTP server running to which you can set the charm's resources_mirror (or equivalent) config option to point to, serving all (--all, optional as well as required) resources defined in the remote resources.yaml (-r <url-or-file>), which are cached in the local_mirror directory (-d local_mirror).

Note that the charms will need to be able to access the machine and port you run the mirror on, and the charms must support a config option to point Juju Resources to the mirror (as well as handle the possibility that their resources may not be available when they are first deployed).