DevOps Engineer Cover Letter Example

Your job post mentions a migration from self-hosted Jenkins to GitHub Actions — I led exactly that migration at Cardstack last year for a 35-person engineering team. I can tell you where the complexity hides and what I would do differently the second time.

At Cardstack I moved 60 pipelines from a single-point-of-failure Jenkins server to GitHub Actions with reusable workflows, achieving zero-downtime migration over three weeks while keeping all teams shipping. Post-migration deployment frequency went from 8 per week to 24 per week, and our average deploy time dropped from 22 minutes to 7 minutes due to better parallelism and caching. MTTR for pipeline failures went from 2 hours to 18 minutes because engineers could diagnose and retry without waiting for a Jenkins admin.

I introduced infrastructure-as-code across the whole platform using Terraform and a GitOps promotion model. Every environment change now goes through pull request review. The result was that the first time a junior engineer accidentally misconfigured a security group, the PR review caught it before it reached staging. Before IaC, that kind of change went directly to production with no audit trail.

I write runbooks for the scenarios I hope never happen. After my first major incident at Cardstack — a misconfigured load balancer that caused 40 minutes of partial downtime — I spent a week documenting every high-risk change pattern with step-by-step rollback instructions. Those runbooks were used twice in the next six months by engineers who were not on call when I wrote them. Happy to share the format if it is useful.