Generalize Infrastructure Roles

date:2017-09-10 14:00
tags:ansible, roles, mariadb, rabbitmq

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Currently openstack-ansible is maintaining infrastructure roles that are used to deploy general infrastructure services such as MariaDB and RabbitMQ, which are applicable in non-OpenStack ansible environments also. With little to no refactoring these roles can be used to deploy the services in other Ansible managed environments also.

By maintaining robust, generalized service roles, they are more likely to be consumed, improved, and maintained by other operators in the greater Ansible community. This will benefit us by training us to keep a modular mindset when building the roles, which leads to better maintainability and wider testing for OSA consumers also.

In some cases we may wish to deprecate our openstack-ansible roles and consume more generalized upstream alternatives.

Problem description

In some of the roles (such as haproxy), we implement a very OSA specific deployment with very little reusability or configurability for a typical HAProxy deployer.

Other roles, such as Galera server, are fairly generalized and robust, but carry the openstack-ansible-service_name naming scheme, making it less likely for anyone NOT using openstack-ansible to use the role in their deployments.

pip_install is an example of a role that will require some minor refactoring to generalize it. The role performs some very out of scope tasks, such as repo management, which have nothing to do with installing pip. These features should be moved to appropriately modularized roles (a general repo management role?), so that pip_install is only doing the work it is meant to do.

Proposed change

Examine the following roles to identify and refactor out of scope tasks and orchestrate openstack-ansible specific configurations at the integrated repo level. If the role is built properly it should offer the necessary service configuration to be injected from the inventory and playbooks.

Roles to examine initially:
  • openstack-ansible-pip_install
  • openstack-ansible-lxc_hosts
  • openstack-ansible-lxc_container_create
  • openstack-ansible-haproxy_server
  • openstack-ansible-memcached_server
  • openstack-ansible-galera_server
  • openstack-ansible-rabbitmq_server
  • openstack-ansible-ceph_client

Once the work outlined above has progressed sufficiently, we should consider renaming some of the roles to a more appropriate naming, ie. openstack-ansible-galera_server becomes ansible-mariadb-cluster, etc.

Alternatives

N/A

Playbook/Role impact

The playbooks and especially inventory should eventually contain all of our openstack-ansible specific configurations. The infrastructure roles themselves should be generalized without an assumption or skew toward being consumed only by openstack-ansible.

In some cases this is already implemented, but in other cases the role will undergo significant changes or wholesale replacement to accomplish this.

Upgrade impact

Consumers of the roles will need to adjust to any major refactorings that take place, including possible renaming of the git sources and role names.

Security impact

N/A

Performance impact

N/A

End user impact

N/A

Deployer impact

Deployers who work frequently with openstack-ansible will benefit from the ability to use the same roles to deploy applicable services for other projects they work on besides OSA.

Developer impact

It is possible that this could draw more developers to assist in maintaining some of the roles. Cosmetic changes such as renaming may also help veteran OSA developers take a more abstract approach when crafting changes to these roles, which should make them more maintainable in the long run.

Dependencies

N/A

Implementation

Assignee(s)

Primary assignee:
Logan Vig (LP: loganv; IRC: logan-)

Work items

  • Examine the infrastructure roles for out of scope tasks or reusability concerns. Address the issues by refactoring or replacing the role.
  • Improve the role documentation if necessary with example playbooks demonstrating ad-hoc usage of the role.
  • Rename the role and repo to a globally namespaced ansible role such as ansible-service-name.

Testing

N/A

Documentation impact

Improving and expanding the role documentation will be beneficial for reusability also.