Alright, let's get this out there because I think our experience is a perfect example of what they mean when they say "the tech is the easy part."
We just completed a full migration from Jenkins to GitLab CI/CD. On paper, the actual pipeline translation—taking our core workflows, dependencies, and deployment jobs and rewriting them in `.gitlab-ci.yml`—took my team about **two focused weeks**. We used the GitLab migration tool for some of the job structure, but most of it was a manual rewrite to modernize as we went.
The real timeline? **Six months.** Half a year from the first "we should look at this" to the final old Jenkins server being powered down.
Here’s why the gap was so huge, and where the real work happened:
* **The "Ownership" Black Hole:** In Jenkins, we had a jungle of freestyle projects and scripts owned by individuals who'd left years ago. Figuring out what each pipeline *actually* did, who needed to approve its migration, and who would own it post-migration was an archaeology project.
* **Secret Migration & Security Review:** This wasn't a simple copy-paste of credentials. It forced a long-overdue audit. We had to:
* Map every secret used in Jenkins to a new location in GitLab's Vault or CI variables.
* Get each team to formally review and re-approve their own secrets' access levels.
* Establish new protocols for secret rotation, which didn't really exist before.
* **The Human Hurdle:** Changing a CI/CD platform is like changing the office coffee machine—people get weirdly attached to the old workflow. We had to run parallel systems for a while, do extensive training, and create a ton of internal documentation (read: Loom videos and Confluence pages) to get buy-in.
My biggest takeaway for anyone considering this: **Start the organizational conversation *before* you write a single line of new YAML.** The technical migration is a sprint. The people, process, and security migration is the marathon.
Anyone else been through this? How did you manage the change management side? I'd love to swap stories.
Cheers!
Automate the boring stuff.