GitLab CI vs GitHub Actions: choosing the one you will not regret

If you are leaving Jenkins, the destination is almost always one of these two, and the choice is usually made by where your code already lives. That is a reasonable default — the integration between source and CI is most of the value — but there are four places where the difference is big enough to override it.

Runner economics

GitHub Actions bills per minute on hosted runners, with a multiplier: Linux ×1, Windows ×2, macOS ×10. Larger runners cost proportionally more. For a team doing a few thousand Linux build-minutes a month, hosted runners are cheap and you should not think about it. For a team doing 200,000 minutes a month, or any macOS at all, the bill becomes a line item worth managing and the answer is self-hosted runners.

GitLab CI bills the same way on GitLab.com shared runners, but the self-hosted runner story is older and more flexible: the runner is one Go binary with a dozen executors (shell, Docker, Kubernetes, custom), it registers with a token, and running your own has been the normal path for years rather than a later add-on.

If you are self-hosting from day one, GitLab's runner is the more mature piece. If you want to never think about runners, Actions' hosted fleet is broader.

Pipeline definition

Actions composes at the step level: an action is a unit you call in a step, versioned by git ref, from a marketplace with tens of thousands of entries. That marketplace is a genuine productivity advantage and a genuine supply-chain surface — a third-party action runs arbitrary code in a job that may hold your cloud credentials. Pin to a full commit SHA, not a tag:

- uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8  # v5.0.0

GitLab composes at the job level with include: and extends:, which pushes you toward a shared pipeline template rather than assembling steps:

include:
  - project: platform/ci-templates
    ref: v4
    file: /service.yml

build:
  extends: .service-build
  variables:
    SERVICE: orders

In practice: Actions is faster to get something working, GitLab is easier to keep a hundred repositories consistent. If you already learned that lesson with Jenkins shared libraries, GitLab's model will feel familiar.

Multi-repo and monorepo

GitLab has first-class parent-child and multi-project pipelines: a job can trigger a downstream pipeline in another project and wait on it, with the whole thing visualised as one graph. If your delivery involves five repositories that must move together, this is the feature you will miss elsewhere.

Actions handles cross-repo through workflow_dispatch and repository_dispatch, which works but is fire-and-forget plumbing you assemble yourself. For monorepos, both need path filters, and both get slow if you skip that step.

Secrets and cloud access

Both support OIDC federation into AWS, Azure, GCP and Vault, and in both cases that is what you should use instead of storing long-lived keys — see CI secrets without long-lived keys. The difference is in the guardrails.

GitLab has protected branches, protected variables and environments with approval rules that are enforced server-side, plus per-environment secrets. Actions has environments with required reviewers and deployment branch rules, which cover the same ground, plus a hard-won set of defaults around pull_request_target and fork PRs that you must understand before allowing external contributions.

The single most important setting in either: restrict which refs can assume your cloud roles. An OIDC trust policy scoped to repo:acme/*:* means any workflow in any branch of any repo in the org can assume that role.

"Condition": {
  "StringEquals": {
    "token.actions.githubusercontent.com:sub": "repo:acme/orders:environment:production"
  }
}

The honest summary

Choose GitHub Actions if your code is on GitHub, your builds are mostly Linux containers, and you value the marketplace more than you fear it. It is the path of least resistance and the ecosystem is where new tooling appears first.

Choose GitLab CI if you self-host, if you need one platform covering source, CI, registry, packages and releases in a regulated or air-gapped environment, or if your delivery genuinely spans repositories that must be coordinated.

Do not choose based on a feature comparison table. Both build containers, run tests in parallel, cache dependencies and deploy to Kubernetes. Choose based on the runner bill at your volume and on which composition model your organisation can actually maintain in two years.

And whichever you pick, keep the pipeline logic in a versioned template repository from the first week. The thing that makes CI migrations expensive is never the YAML syntax; it is the two hundred repositories that each invented their own.