Adding a new service

When adding a role for a new service in Ansible, there are couple of patterns which Kolla uses throughout and which should be followed.

  • The sample inventories

    Entries should be added for the service in each of ansible/inventory/multinode and ansible/inventory/all-in-one.

  • The playbook

    The main playbook that ties all roles together is in ansible/site.yml, this should be updated with appropriate roles, tags, and conditions. Ensure also that supporting hosts such as haproxy are updated when necessary.

  • The common role

    A common role exists which sets up logging, kolla-toolbox and other supporting components. This should be included in all services within meta/main.yml of your role.

  • Common tasks

    All services should include the following tasks:

    • deploy.yml : Used to bootstrap, configure and deploy containers for the service.

    • reconfigure.yml : Used to push new configuration files to the host and restart the service.

    • pull.yml : Used to pre fetch the image into the Docker image cache on hosts, to speed up initial deploys.

    • upgrade.yml : Used for upgrading the service in a rolling fashion. May include service specific setup and steps as not all services can be upgraded in the same way.

  • Log rotation

    • For OpenStack services there should be a cron-logrotate-PROJECT.conf.j2 template file in ansible/roles/common/templates with the following content:

    • For OpenStack services there should be an entry in the services list in the cron.json.j2 template file in ansible/roles/common/templates.

  • Log delivery

    • For OpenStack services the service should add a new rewriterule in the match element in the 01-rewrite.conf.j2 template file in ansible/roles/common/templates/conf/filter to deliver log messages to Elasticsearch.

  • Documentation

    • For OpenStack services there should be an entry in the list OpenStack services in the README.rst file.

    • For infrastructure services there should be an entry in the list Infrastructure components in the README.rst file.

  • Syntax

    • All YAML data files should start with three dashes (---).

Other than the above, most service roles abide by the following pattern:

  • Register: Involves registering the service with Keystone, creating endpoints, roles, users, etc.

  • Config: Distributes the config files to the nodes to be pulled into the container on startup.

  • Bootstrap: Creating the database (but not tables), database user for the service, permissions, etc.

  • Bootstrap Service: Starts a one shot container on the host to create the database tables, and other initial run time config.

Ansible handlers are used to create or restart containers when necessary.