Alright, let's get this out there before I'm accused of being "helpful" or "productive." We've all been through it: you spin up a new cluster on Yet Another Managed Kubernetes Service™, you go to install the `kube-prometheus-stack` Helm chart because, let's be honest, it's the default, and suddenly you're neck-deep in permission errors, missing CRDs, or your node-exporter is having a meltdown because the host filesystem path is wrong. Why? Because the "standard" chart makes a hilarious number of assumptions about *its* standard environment, which of course doesn't exist.
So, in a fit of pique, I built a script. It doesn't deploy anything. It just compares the *default* values of the `kube-prometheus-stack` chart against the actual, real-world defaults of the major distributions. The goal was to map the minefield. The results are, predictably, a mess of silent failures waiting to happen.
The script essentially does a diff between the chart's vanilla `values.yaml` and a curated set of "distribution profiles" I had to manually piece together from forums, docs, and bitter experience. It highlights where the defaults are dangerously incompatible. A few choice findings:
* **NodeExporter Host Paths:** The chart assumes a standard host filesystem layout (`/sys`, `/proc`, etc.). This is fine on a raw cluster. Now try it on GKE's Container-Optimized OS, or AWS's Bottlerocket. Suddenly your paths are wrong, or you need entirely different mounts. The script flags this as a critical path mismatch.
* **Prometheus Operator ClusterPermissions:** The chart's RBAC defaults are... optimistic. On distributions like OpenShift or even EKS with certain IRSA configurations, the default service account permissions are a fraction of what the operator expects. The script lists the specific rules most likely to cause a `CreateContainerConfigError` or a silent failure to create ServiceMonitors.
* **CoreDNS vs. kube-dns:** This one's a classic. The chart's default Prometheus scrape job for `coredns` will gracefully do nothing on a cluster running `kube-dns`. It's not a failure, just a gaping hole in your monitoring you won't notice until you wonder why you have no DNS metrics. The script tags this as a "silent skip."
* **Network Policies & PSPs:** Depending on the distribution's Pod Security Standard defaults (or legacy PSPs), the Prometheus or Alertmanager pods might get blocked from talking to the API server. The script doesn't solve your policy writing, but it does warn you that the chart's `networkPolicy.enabled: false` default is a hard requirement on some platforms unless you're prepared to write a lot of YAML.
The takeaway isn't that any one distribution is "better." It's that the entire industry's reliance on a "standard" chart is a case study in survivorship bias. The people who claim "it works fine!" either got lucky with their platform's defaults, or they've already bled all over their keyboard debugging it and forgot the pain. The operational overhead isn't in running Prometheus; it's in the 2-3 hours of initial configuration triage that nobody talks about.
I'm still cleaning up the script (it's currently a ugly bash and jq monstrosity), but the real question for the thread is: **What other distribution-specific landmines have you found with this stack?** I'm looking for the subtle stuff—the defaults that *almost* work but then break at 3 AM during a scale event.
Specifically:
* On AKS with Calico network policies, did you have to make specific allowances?
* For Rancher or OpenShift users, what are the mandatory value overrides you *always* have to set?
* Has anyone compared the actual resource *requests/limits* needed across distros? The chart defaults seem both over- and under-provisioned depending on the cloud provider's kernel overhead.
Let's compile the real, tacit knowledge instead of pretending one size fits all.
🤷
Oh man, you're singing my song. The silent failure point is so real. I once spent half a day trying to figure out why my Prometheus storage retention was 2 days on a new EKS cluster, only to find the default `persistentVolume` size was something tiny and it had filled up immediately. The chart default assumes infinite disk!
Do you have GKE's "in-cluster config" profile in your script? Their auto-negotiated ports for node-exporter are different last I checked, and it'll just... not scrape if you don't catch it. A diff would've saved me.
Also, brilliant idea. Can we bug you to share the script on GitHub? I'd love to add a DigitalOcean Kubernetes profile to it.
cost first, then scale
The GKE in-cluster config point is exactly the kind of thing this community needs to surface more. I've seen whole teams burn cycles debugging node-exporter scrape targets only to realize the port mismatch was a documented but rarely advertised quirk. Your offer to add a DigitalOcean profile is great - that kind of shared, battle-tested knowledge is way more valuable than anything in a vendor's quickstart guide.
One thing I'd flag as a moderator though: if the script gets shared publicly, maybe consider a permissive license and a warning that these profiles are snapshots, not guarantees. Cloud providers update defaults without fanfare. Are you still on the EKS version that gave you that persistentVolume shock, or have you since migrated?
Stay curious, stay skeptical.