Hi everyone, I've been lurking for a bit but this is my first post. I'm helping a small team get our CI/CD setup in order, and honestly, I'm a bit in over my head 😅.
We wanted a "modern" setup, so we went with Jenkins running on a Kubernetes cluster in our cloud provider (I'd rather not say which one just yet). The idea was to be scalable and efficient. But our monthly bill has been... shocking. Our cloud credits are evaporating way faster than we projected, and I'm scrambling to figure out why.
Our setup is pretty basic: a few build agents in pods, building maybe 50-60 times a day for a couple of small web apps and a Python service. I expected some cost, but not this much. I'm looking at the node utilization and it feels like we're paying for a lot of idle time, but I'm not sure how to tighten it up without breaking things.
I'd love some real-world advice from anyone who's been here. Did we go wrong with Jenkins on K8s for a small team? Should we be looking at a managed service instead, or are there specific configurations (like scaling down to zero, or different resource requests/limits) that can make this viable? I really want to make this work, but I also need to make the business case to my team if we need to switch tracks.
Any guidance or even just a breakdown of what costs we should realistically expect would be a huge help. Feeling a bit lost!
Ah, the "modern" setup tax. You paid it in full. The shocking part is you thought it would be scalable *and* efficient for a small team. That's the vendor's story, not the reality.
You're paying for idle time because you're almost certainly running static nodes or a controller pod 24/7. Jenkins on K8s for small-scale work is a classic case of over-engineering for the brochure, not for the bank statement. The complexity you've added to shave seconds off a build is costing you dollars per hour.
Before you jump to a managed service, which just trades one bill for another, find out what your idle-to-build time ratio is. If your pods are sitting idle for 90% of the day, you've already answered your own question. Look at your cloud console's cost breakdown - I guarantee the line item for the control plane and the persistent disks will be an education.
Procurement Cynic
While the core point about idle costs is valid, calling it the "modern setup tax" misattributes the problem. The issue isn't the stack itself, it's a failure to implement the stack's actual scaling mechanisms.
You've correctly identified the symptom - static nodes and a persistent controller. But that's a configuration failure, not an inherent flaw of Jenkins on K8s. The whole point of the Kubernetes plugin is dynamic, on-demand agent provisioning. If they're running static pods, they've just recreated a VM-style setup with extra orchestration overhead and are paying for the worst of both worlds.
The real "brochure vs. reality" gap is that implementing proper, cost-aware scaling requires tuning the pod templates, resource requests, and scale-down delays - which is non-trivial. The vendor sold them an auto-scaling fantasy without mentioning the configuration burden. So they're left with the default, which is indeed just always-on VMs in pod clothing.
You're spot on about it being a configuration failure. I've audited a few of these setups, and the "static pods in pod clothing" pattern is sadly common. It's a checklist problem: "Deploy Jenkins on K8s" gets ticked, but "Configure proper scaling" gets forgotten because it's complex.
Your point about the vendor selling the fantasy hits home. But I'd add that the security implications are rarely considered in that gap. A poorly tuned scale-down delay, for instance, can leave orphaned pods with elevated privileges running longer than needed, expanding the attack surface. People chase cost optimization without realizing they're also optimizing for risk.
The real tragedy is they're now paying a premium for a system that's less secure and less cost-effective than a simple, well-managed VM would have been.
Jane