[Feature flag] Rollout of `vue_epics_list`

What

Epics list page is being implemented using issuable_list which includes support for async tab switching, filtering and pagination. The implementation is currently behind feature flag :vue_epics_list and can be enabled on per-group basis from Rails console by running Feature.enable(:vue_epics_list, Group.find_by_full_path('gitlab-org')).

Remove the :vue_epics_list feature flag ...

Owners

• Team: groupproduct planning
• Most appropriate slack channel to reach out to: #s_plan
• Best individual to reach out to: @kushalpandya

Expectations

Visually only major change that Epics list will have is lack of numbered pagination that's because we're using GraphQL to fetch Epics list and it doesn't support numbered page navigation. Instead, user will see only Prev & Next buttons.

Older Epics List	Vue Epics List

What are we expecting to happen?

Epics list to render asynchronously after page is loaded and then all user interactions (tab switch, filtering, sorting and pagination) happening on listing page to be async as well.

What might happen if this goes wrong?

Listing page may be slow to load compared to HAML implementation.

Beta groups/projects

If applicable, any groups/projects that are happy to have this feature turned on early. Some organizations may wish to test big changes they are interested in with a small subset of users ahead of time for example.

• gitlab-org/gitlab-com groups

Roll Out Steps

• Enable on staging (/chatops run feature set --group=gitlab-org vue_epics_list true --staging)
• Test on staging
• Ensure that documentation has been updated
• Enable on GitLab.com for individual groups/projects listed above and verify behaviour (/chatops run feature set --group=gitlab-org vue_epics_list true)
• Coordinate a time to enable the flag with the SRE oncall and release managers
  • In #production by pinging @sre-oncall
  • In #g_delivery by pinging @release-managers
• Announce on the issue an estimated time this will be enabled on GitLab.com
• Enable on GitLab.com by running chatops command in #production (/chatops run feature set --group=gitlab-org vue_epics_list true)
• Cross post chatops Slack command to #support_gitlab-com (more guidance when this is necessary in the dev docs) and in your team channel
• Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel

Rollback Steps

• This feature can be disabled by running the following Chatops command:

/chatops run feature set --group=gitlab-org vue_epics_list false