Build and release workflow/UI

[timothyb89]

With release plugins (#9) and repository hooks (#19) we have a decent story for managing the whole CI/CD process, at least on the backend. However, we still need to give users control over how and when a change is is built and released. Ideally this should integrate directly with GitHub issues/pull requests and we should avoid having any external UI.

One idea is for the bot to detect changed modules in a particular PR. It can then leave a comment on the PR users can interact with. Examples in followup comments.

[timothyb89]

Example: monasca/monasca-docker#324. Makes changes to and releases a new version of a semver module. With this workflow the version bump in grafana/build.yml and .env would be automatically created by the pr-bot in a follow-up PR. A comment on the user's PR might look like:

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Modules affected by this change:

• grafana - 2 downstream modules

No modules have been selected for release. Click a checkbox above or comment @monasca-ci release <modulename> [level] to perform a release.

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If the user clicks the checkbox it will edit the bot's comment. All allowed users may not be able to edit comments, so they can also comment by @-ing the bot. Clicking a checkbox results in a patch release by default, and @-syntax can be used to specify a major or minor release instead.

If a release is specified the bot will update its comment (and perhaps leave another comment acknowledging the user request). If a user requests a minor update:

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Modules affected by this change:

• grafana - minor - 2 downstream modules

The following modules will be released:

• grafana: new minor version 4.0.0-1.3.0, updating:
  • docker-compose in monasca-docker
  • monasca in monasca-helm

Click a checkbox above or comment @monasca-ci release <modulename> [level] to perform a release. Don't want to release? Uncheck or @monasca-ci release <modulename> to toggle.

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Once the change is merged the bot will file release PRs and should leave another comment linking to them.