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README.md

Up and Running with Ansible

This is meant to be a quick guide to getting going with Ansible with this project.

Before executing playbooks, this project makes use of roles from galaxy.ansible.com which need to be installed prior to use.

Galaxy Roles

These roles are listed in the requirements.yml file and added to the workstation by issuing:

ansible-galaxy install --roles-path ./galaxy -r requirements.yml

The ansible.cfg file includes the directive to include the ./galaxy directory when looking for roles.

Vault Utilization

This project makes use of the ansible-vault for encrypting settings. To work with the vault files use the --vault-id parameter to pass the location of the vault id file.

To access/edit the contents of the vault file use:

ansible-vault --vault-id <path/to/vault/id> edit vars/settings.yml

Playbooks

The heart of using Ansible for systems management is the use of playbooks to execute commands on the various systems. Details on the playbooks themselves is listed below.

Executing playbooks is done via the ansible-playbook command. When executing the playbook runs as your user, with your privileges. If changing users is required (sudo access), then your password can be prompted for with --ask-become-pass.

An example command for deploying docker to all systems:

ansible-playbook --ask-become-pass \
  -i inventories/production \
  --limit lw-mc-01.metacpan.org \
  playbooks/provision_docker.yml

This playbook execution shows some of the common options when executing Ansible playbooks:

  • -i

    The Ansible inventory to run the playbook against, in this case production

  • --limit

    Within the inventory only run the playbook against this host or group, in this case lw-mc-01.metacpan.org

  • --ask-become-pass

    The user executing the playbooks password on the remote systems to be used by the sudo command

Additional verbosity can be added to the output produced by ansible-playbook by adding the -v option. The number of vs added corresponds to the amount of verbosity.

Usage of the Ansible vault was dicussed previously and is available as part of the ansible-playbook command, however the example command does not make use of any values stored in the vault.

Playbook Details

The playbooks are divided into two groups by prefix, provision* and deploy*.

Provision playbooks are meant to be executed when setting up new servers or environments. The general idea is they contain plays that are run once, or very rarely. However that doesn't mean that they should not be idempotent. All playbooks must be idempotent.

The deploy playbooks are meant to be executed all the time and can be run multiple times throughout the day. They're individual pieces of the environment, meant to be executed quickly, with one big deploy playbook to manage all the plays should need be.

provision_docker.yml

Adds the docker installation repository and then installs docker and docker-compose.

deploy_docker_mgmt.yml

This role clones the metacpan-docker-production repository onto the servers that are part of the inventory group container_hosts.

This is the lowest level of the docker deployment playbooks and is required to be run before deploying any other docker based sites.

Variables used by this playbook can be defined in the inventory group_vars/container_hosts.yml file

---

docker_mgmt:
  directory: /home/metacpan/docker-production
  git:
    repo: https://github.com/metacpan/metacpan-docker-production
    version: master
    user: metacpan

These values are used by the Ansible git task to perform the actual cloning.

Roles

deploy_site

deploy_site is a base level role that is to be used for all sites within the metacpan-docker environments. The site variable is a required setting and must match the name of the service to be started, and the configuration values in the var/settings.yml file.

The deploy_site role is comprised of 3 parts:

  1. configure
  2. compose_pull
  3. compose_up

configure

The configure phase integrates the values for the site in vars/settings.yml into the {{ site }}/environment.json file. Site settings keys are used to search the environment file for matching keys, and the values from settings are substituted. This allows for separation of development/test values and those used in production.

compose_pull

The compose pull phase issues the docker-compose pull {{ site }} command in order to make sure that the local images are up to date with the latest releases before starting the containers.

compose_up

The compose up phase starts the containers as necessary by issuing the docker-compose up -d {{ site }} command.

env_files

The env_files role writes settings specified in the env variable to the environment file named for the value in the container variable. If none is specified the .env file is updated instead.

    - name: Set logging environment
      include_role:
        name: env_files
      vars:
        container: logging
        env: "{{ logging.environment }}"

Warnings & Troubleshooting

The python library urllib3 may need to be updated on each system in order to install docker.

pip install urllib3 --upgrade
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