0k-charms/README.org

• 0k-charms
• Maturity
• Usage
  • Through compose for full deployment of sets of services
  • Through lxc-deploy for full install and deployment of services
  • Through docker-build-charm for docker image creation
  • Through 0k-charm for bare hosts installs
• Installation
• Specs
  • charm type

0k-charms

This package provides charms, which are special system recipes, that are meant to be executable and mangled together to allow managing a wide set of services.

Inspired by juju charms, these are mostly bash scripts organized by service and meant to automate all administration tasks, from installation, to connection with other services, or any other task a service would need.

Several tools are able to read the current state of this repository to effectively deploy full production grade services on different type of platform.

The only real fully functional implementation is 0k-compose. It will use these charms to drive, prepare, and build in docker, complete sets of services.

Another old solution called lxc-deploy was used actively before to deploy services on LXC tool set until 2016 using these charms.

Bare hosts can also replay some recipes to install services directly on them via the 0k-charm project using the charm apply command. Note that actually, as most recipes are bash executable, it is still a viable option to copy-paste parts of source-code of these scripts. These last two options are still used very often to bootstrap installs of docker-hosts for instance.

Maturity

Charms in these repository are in a wide set of maturity, from simple note taking of shell commands, not even executable, to full charm allowing to deploy services and manage the full life cycle of the service.

The repository in a whole is thus NOT considered as mature at all, and will require some thorough cleaning and decisions to furthermore structure to reach a state where it'll make sense to go full public.

Usage

TODO Through compose for full deployment of sets of services

Requires 0k-compose package that contains the compose command line tool.

TBD

TODO Through lxc-deploy for full install and deployment of services

Requires lxc-scripts package that holds several tools for LXC management, amongst them is lxc-deploy.

TBD

TODO Through docker-build-charm for docker image creation

Requires 0k-docker package that holds several tools for docker management, amongst them is docker-build-charm.

docker-build-charm will use the install recipes in a charm to basically mimic the Dockerfile purpose and create a docker image for a specific service.

TBD

TODO Through 0k-charm for bare hosts installs

Requires 0k-charm package to get the charm command line util.

TBD

Installation

Most tools should check the CHARM_STORE bash environment variable that should be the path to reach the root of this repository. If not defined, most tools will look in /srv/charm-store by default.

Specs

charm type

Not all charm are intended to bring up services as having a container always running and listening.

In metadata.yml, the root level type can be one of:

• service (default)

  If not specified, this is the default. A charm brings up a service. It is meant to be always running. For instance, apache, mysql, postgres are services.

  They usually open ports and are listening to provide their service, or carry background listening of other ressources (like checking time and sending scheduling command for the cron services), and or use files to trigger or report on their activity.

  It will have an entry in the final docker-compose.yml, and thus, a container will run and stay in memory and have a restart: unless-stopped policy. They use CPU and memory ressources.

• run-once

  The entry is meant to describe a command that run once, it will be called by a service and will exit after execution.

  For instance, logrotate, rsync-backup, or letsencrypt are of type run-once.

  They are meant to be run by service for specific events. They usually will use relations to ensure they are called at specific moment by service…

  A command does not have an automatic restart policy as services have.

  They use CPU and memory ressources only when run and gives them back once finished.

• stub

  The entry describes an entity that will not be run at all. It is used to hold information in the compose.yml and often to stand for a real service managed outside of compose.yml (on an other host or on a different managing system, like a local installation or LXC, virtualbox, …).

  For instance, stmp-stub can be used to stand for an external smtp.

  It is through their relation that they shine as they can provide similar interface than actual services would have provided. smtp-stub is a smtp-server provider and other charm can connect to it.

  They usually implement relation hooks, and are providers.

  No entry will be created in the final docker-compose.yml.

  They use no CPU or memory ressources at all.