### Summary The option to use Puma was recently added to Omnibus. The Helm charts don't currently have this option. ### Problem statement Without Puma support, the Helm Chart's functionality is trailing behind the options available in the Omnibus, and this includes other functionality that is only available with Puma like [GitLab's Dependency Proxy](https://docs.gitlab.com/ee/administration/dependency_proxy.html). ### Proposal We should ship support for enabling puma. It should be optional, and not the default. It should be clearly documented that it is a currently unsupported feature. To match omnibus support added in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/3846 Related to https://gitlab.com/groups/gitlab-org/-/epics/465 As puma is already part of the `gitlab-rails` images, we probably want to branch off separate `gitlab-puma-Xe` images similar to the unicorn images. This will also unblock https://gitlab.com/charts/gitlab/issues/1284