docker distribution #0

Supports: trusty

Description

A layer to deploy an AWS s3 backed Docker Distribution daemon


Charm Layer for Docker

This repository contains the Charm layer for docker, which can be used as a base layer for other Charms that use docker. Please refer to the Juju composer docs.

Usage

In a charm that wants to use docker, the integration can be as simple as placing the following in your charm's compose.yaml:

includes: ['layer:docker']

From here, you simply amend any hooks/reactive patterns you require to deliver and manage the lifecycle of your applications docker image.

States

The docker layer raises a few synthetic events:

  • docker.ready

  • docker.available

docker.ready

When docker.ready is set, this event is before we signify to other layers that we are ready to start workloads, which should allow for docker extensions to be installed free of disrupting active workloads.

For example, installing SDN support and getting the daemon configured for TCP connections.

@when('docker.ready')
def start_flannel_networking():
    # do something here
docker.available

When docker.available is set, the daemon is considered fully configured and ready to accept workloads.

@when('docker.available')
def start_my_workload():
    # do something with docker

Docker Compose

This layer installs the 'docker-compose' python package from pypi. So once the Docker layer is installed you have the ability to use Docker Compose functionality such as control files, and logging.

Memory Accounting

The charm supports altering the GRUB2 options enabling CGROUPS and memory accounting. Changing this value will reboot the host, and any running workloads are at the mercy of the charm author inheriting from this charm. Please use --restart=always on your container runs that need to be persistent.

charms.docker

This layer also includes a wheelhouse of charms.docker a python library to make charming with docker, and configuring the docker daemon much easier, and syntactically enjoyable. For more information about this library see the project

Credit

This charm contains a slightly modified copy of the script contained at: https://get.docker.io

The modifications were raising status messages for Juju so its apparent what is happening to the end user following along with Juju's extended status feature.


Configuration

enable-cgroups
(boolean) Enable GRUB cgroup overrides cgroup_enable=memory swapaccount=1. WARNING changing this option will reboot the host - use with caution on production services
password
(string) Default administrative user password of the registry
user
(string) Default administrative user of the registry