Add Support for Custom TripleO Validations

https://blueprints.launchpad.net/tripleo/+spec/custom-validations

All validations are currently stored in a single directory. This makes it inconvenient to try and write new validations, update from a remote repository or to add an entirely new (perhaps private) source.

Problem Description

  • The deployer wants to develop and test their own validations in a personal checkout without risking changes to the default ones.
  • The deployer wants to use a stable release of TripleO but consume the latest validations because they are non-disruptive and check for more stuff.
  • A third party has developed validations specific to their product that they don’t want to or can’t include in the tripleo-validations repository.

Proposed Change

Overview

We will store a default set of TripleO validations in a Swift container called tripleo-validations. These will be shared across all plans and are not expected to be updated by the deployer. This container should be created on initial undercloud deployment.

We will provide a mechanism for deployers to add a custom set of validations per deployment plan. These plan-specific validations will be stored in a custom-validations subdirectory in the plan’s Swift container. Storing them together with the plan makes sense as these validations can be specific to particular deployment plan configuration, as well as makes the import/export easier.

Since custom validation will be stored as part of the plan, no additional workflows/actions to perform CRUD operations for them will be necessary; we can simply use the existing plan create/update for this purpose.

The validation Mistral actions (e.g. list and run_validation) will need to be updated to take into account this new structure of validations. They will need to look for validations in the tripleo-validations Swift container (for default validations) and the plan’s custom-validations subdirectory (for custom validations), instead of sourcing them from a directory on disk, as they are doing now.

If a validation with the same name is found both in default in custom validations, we will always pick the one stored in custom validations.

Note

As a further iteration, we can implement validations as per-service tasks in standalone service Ansible roles. They can then be consumed by tripleo-heat-templates service templates.

Alternatives

  • Do nothing. The deployers can already bring in additional validations, it’s just less convenient and potentially error-prone.
  • We could provide a know directory structure conceptually similar to run-parts where the deployers could add their own validation directories.

Security Impact

None

Other End User Impact

In order to add their own validations, the deployer will need to update the deployment plan by adding a custom-validations directory to it, and making sure this directory contains the desired custom validations. The plan update operation is already supported in the CLI and the UI.

Performance Impact

Since the validation sources will now be Swift containers, downloading validations will potentially be necessary on each run. We will have to keep an eye on this an potentially introduce caching if this turns out to be a problem.

Other Deployer Impact

None

Developer Impact

Testing and developing new validations in both development and production environments will be easier with this change.

Implementation

Assignee(s)

Primary assignees:
  • akrivoka
Other contributors:
  • florianf

Work Items

  • Move to using Swift as default storage for tripleo-validations ([1]).
  • Update load_validations and find_validation functions to read validations from all the sources specified in this document.

Dependencies

In order to be able to implement this new functionality, we first need to have the validations use Swift as the default storage. In other words, this spec depends on the blueprint [1].

Testing

The changes will be unit-tested in all the tripleo repos that related changes land in (tripleo-common, instack-undercloud, tripleo-heat-templates, etc).

We could also add a new CI scenario that would have a custom-validations directory within a plan set up.

Documentation Impact

We will need to document the format of the new custom-validations plan subdirectory and the new behaviour this will introduce.