GitHub Actions vs Jenkins: Which CI/CD Tool in 2026?

The Jenkins master node went down on the morning of our biggest release of the quarter. PagerDuty fired, and when I checked the status, every pipeline across every team had stopped. Before I even started diagnosing, I caught myself thinking: why are we still running this thing?

TL;DR: After years on Jenkins, I moved our platform to GitHub Actions and measured a roughly 20% reduction in release-related work time (self-reported by teams). Whether you should make the same move depends on your context — here's the reasoning I actually used.

What I Was Trying to Do#

Before moving into SRE, I worked on ERP systems. Jenkins was already there, and it was just how CI/CD worked. You created jobs manually, wrote Groovy scripts, and managed plugins. That was the job.

When I joined the SRE team, I inherited a Jenkins setup that multiple teams depended on. Hundreds of job definitions, a Shared Library built over years, and plugin dependencies going back eight years. My first job wasn't to modernize it — it was to not break it.

That changed over time. The conviction that we needed to move grew slowly, but the master node incident is where it crystallized.

What Went Wrong (and Why)#

The problems with Jenkins weren't surface-level. They went all the way down to architecture.

Single Point of Failure#

When the master node goes down, everything stops. You can mitigate this with a Controller/Agent setup, but you never eliminate the dependency on the controller. The incident that started this story was caused by disk exhaustion — build logs had filled the volume. Recovery took thirty minutes. But across all the teams that were blocked, the total lost time was significant. I calculated it afterward: the aggregate engineering hours lost were in the dozens.

Groovy Debugging Costs#

Jenkins Shared Libraries are written in Groovy — dynamically typed, with limited IDE support. "What does this method accept?" meant reading documentation or just running it and watching it fail. Testing was possible, but most meaningful tests required a running Jenkins instance. Nothing could be validated locally in a clean way.

One change I made to the Shared Library affected over a hundred jobs. The change itself was a one-line bug fix. Understanding the impact took half a day.

Plugin Gravity#

The Jenkins plugin ecosystem is rich, but maintaining it is expensive. Compatibility issues between versions come up regularly, and every update carries the implicit question: what's going to break this time? I remember spending half a day debugging a Slack notification plugin that stopped working after a security update. The fix was straightforward — but finding it wasn't.

The Fix — Step by Step#

The migration wasn't a cutover. It was a deliberate, slow transition.

Step 1: New repositories get GitHub Actions#

I didn't migrate existing Jenkins jobs. Instead, I made a rule: any new project or repository starts on GitHub Actions. This kept migration costs low and gave teams time to learn the new patterns before we touched anything critical.

My reasoning was simple — migration is a people problem before it's a technical one. Swapping everything at once creates a period where nobody knows how anything works. A gradual approach meant teams could build familiarity while the old system stayed stable.

Step 2: Design for the golden path#

With GitHub Actions, workflows live in YAML and can be composed through reusable workflows and Composite Actions. The design decision I cared about most wasn't syntax — it was philosophy.

Instead of documenting best practices and asking teams to follow them, I built reusable workflows where the default behavior was the right behavior:

# Teams call this and get security scanning, caching, and notifications for free
jobs:
  deploy:
    uses: ./.github/workflows/standard-deploy.yml
    with:
      environment: production
    secrets: inherit

YAML is less expressive than Groovy. That's real. But it's readable in a diff, it has IDE completion, and it doesn't require a running Jenkins to test.

Step 3: Run both systems in parallel#

Jenkins stayed alive for two years while we migrated. This wasn't ideal, but it was realistic. You can't migrate a decade of CI/CD overnight without breaking teams. During this period I learned that self-hosted runners on EC2 work well for cost management — I'll cover that in a separate post.

Step 4: Measure the outcome#

After the migration reached critical mass, I ran a team survey: how has the time you spend on release-related work changed? The average response was about 20% less.

I'm not going to oversell that number. 20% isn't dramatic. But applied across multiple teams over multiple months, it compounds. When I calculated the aggregate time freed across three teams over six months, it came close to one engineer's full capacity.

What I'd Do Differently#

I would have introduced security scanning earlier.

Moving to GitHub Actions made it obvious how much tighter the integration with GitHub Advanced Security, Dependabot, and secret scanning could be. This wasn't impossible on Jenkins — but it required deliberate effort. I kept deferring it until after the migration. In hindsight, that was the wrong call.

I would have tracked the Jenkins tax from day one.

When I made the case for migration, I had qualitative frustration: Groovy debugging is painful, plugin management is unreliable. What I didn't have was data. If I'd been recording "time spent investigating Shared Library blast radius" or "hours lost to plugin failures," I'd have had a cleaner argument for leadership and a clearer signal about when migration had paid off.

Next time I face a similar decision, I'm measuring from the start.

Key Takeaways#

Two questions I use when someone asks whether they should switch from Jenkins to GitHub Actions:

1. Does your team want to build a CI/CD platform or use one?

Jenkins gives you the freedom to construct exactly the tooling you need. If you have hard requirements — unusual execution environments, strict on-premises constraints — that freedom has real value. If you don't, you're paying the maintenance cost without getting the benefit.

2. Are you already using GitHub for source control?

If yes, the integration cost with GitHub Actions is close to zero. PR status checks, secrets management, runner management — it all lives in the same system. That coherence is worth something.

FAQ#

Q: How long does migrating from Jenkins to GitHub Actions take?

A: Expect six months to two years, depending on team size and pipeline complexity. In my case, moving ten teams to full GitHub Actions coverage took roughly two years — but we weren't migrating full-time. We ran both systems in parallel and let new projects land on GitHub Actions naturally. Projects that try to migrate everything at once tend to stall somewhere in the middle.

Q: Is GitHub Actions cheaper than running Jenkins?

A: GitHub Actions is often cheaper — but Jenkins hides its real costs. For smaller teams, GitHub Actions' free tier often covers it. At scale, hosted runner costs grow, and self-hosted runners on EC2 become a practical alternative. Jenkins looks free, but the true cost includes master node operations, plugin maintenance, and the engineering time that goes into failure recovery. In every case where I've done an honest accounting, the "free" Jenkins setup wasn't cheaper than it appeared.

Q: Can I use GitHub Actions with on-premises or self-hosted infrastructure?

A: Yes. Self-hosted runners let you execute jobs on your own servers while keeping workflow definitions in GitHub. For environments with restricted connectivity, GitHub Enterprise Server is another option. The workflow syntax stays the same — only the execution environment changes.

Q: Is YAML reusability as good as Jenkins Shared Libraries?

A: Honestly, no. Groovy is a general-purpose programming language; YAML isn't. GitHub Actions has real expressiveness limits. That said, reusable workflows and Composite Actions handle around 80% of what I've needed. For the remaining 20% — complex logic that doesn't fit in YAML — writing a custom Action in TypeScript or falling back to shell scripts is the practical pattern.

Q: How do you debug GitHub Actions workflows when something goes wrong?

A: Better than I expected coming from Jenkins. For local validation, act lets you run workflows on your machine. In GitHub itself, the step-by-step log UI is cleaner than the Jenkins console output, and finding the failure point is usually faster. When I'm stuck on something non-obvious, setting the ACTIONS_STEP_DEBUG secret to true gives verbose output that usually surfaces what's happening.

This article draws on the author's experience working as an SRE across multiple organizations. Some descriptions — including specific timelines, team interactions, and internal decisions — are illustrative reconstructions based on that experience, not verbatim accounts. Details that could identify specific companies or individuals have been omitted or generalized.