Add Matthias Käppler as backend maintainer (gitlab)

Trainee maintainer issue: #6363 (closed)

Overview

I've been a Senior Engineer on the Memory team since October 2019. As we spend a lot of time in analysing application performance, our MR throughput might lag behind that of product teams, but we do get exposure to a lot of different aspects of the entire GitLab stack. Since my joining the team and company, I have been working on the following things:

• Import/export batch job performance and tooling
• Threading and connection pooling related aspects
• Usage Ping and application telemetry
• Dynamic image scaling (blogged about it here)
• Improvements to Prometheus application metrics
• Database related helpers
• Writing performance related RuboCops
• Contributed to ChatOps functionality
• Contributed to gitlab-compose-kit

I have also been a database reviewer for several months now.

Some contribution related stats (authored + reviewed MRs):

• Total: 148 merged MRs, 154 reviewed.
• gitlab: 74
• workhorse: 16
• GCK: 16

(just listing the repos where the primary focus has been)

Examples of reviews

• gitlab-org/gitlab!48687 (merged) (large MR that was difficult to review, but I think I helped improving it, e.g. to keep our architectural boundaries intact)
• gitlab-org/gitlab!49157 (merged) (it had an interesting discussion around when to abstract over common behavior)
• gitlab-org/gitlab!40971 (merged) (another long review with several rounds of feedback where I thought the end result was a definite improvement)

Things to improve

There are some definite challenges for me becoming a GitLab maintainer due to the nature of my role.

• Domain knowledge: Since our team does not work on expanding the suite of features in GitLab, but rather look after performance (which is often a more low-level kind of work), it is more difficult for us to build domain knowledge.
• The intersection of frontend and backend (e.g. ERB view rendering): since this is not something I am regularly exposed to.
• GraphQL: I have reviewed several MRs now that involved GQL, but I have yet to work with it in-depth myself.

I think all of these will improve with time, both by reviewing more MRs but also because my role tends to send me all over the code base.

@gitlab-org/maintainers/rails-backend please chime in below with your thoughts, and approve this MR if you agree.

Developer checklist

• Before this MR is merged
  • Mention @gitlab-org/maintainers/rails-backend, if not done (this issue template should do this automatically)
  • Assign this issue to your manager
• After this MR is merged
  • Request a maintainer from the #backend_maintainers Slack channel to add you as an Owner to gitlab-org/maintainers/rails-backend
  • Consider adding 'backend maintainer' to your Slack notification keywords

Manager checklist

• Before this MR is merged
  • The MR has been open for 5 working days
  • More than half of the existing maintainers approve the MR
  • There are no blocking concerns raised (if there are, please follow https://about.gitlab.com/handbook/engineering/workflow/code-review/#how-to-become-a-project-maintainer)
• After this MR is merged
  • Announce the good news in the relevant channels listed in https://about.gitlab.com/handbook/engineering/#keeping-yourself-informed