Changing a manifest in a live cluster is quick to do and easy to get wrong. At Demuxer we build Kuberniq, a desktop Kubernetes client for macOS and Windows, and this article shows its YAML editor, which checks each field against the schema the cluster serves and shows the diff before anything is sent.

The problem

kubectl edit deployment web opens the manifest in your terminal editor, with no idea of what each field accepts. Type replicas: "three" and you only find out when you save and the API server refuses it. Once the edit goes through, you don't get a view of what changed against what was in the cluster unless you keep a copy and run kubectl diff on it.

How Kuberniq does it

The Compare Deployment web dialog of Kuberniq, with In the cluster against After applying and 1 change, replicas 2 to 3

  1. Open Deployments and click web. The manifest opens in an editor tab, with Compare… and Apply at the top.
  2. On line 15, change replicas: 2 to replicas: "three". Kuberniq marks the value as you type, and hovering it shows spec.replicas, its type, integer, and the documentation the cluster serves for it: "Number of desired pods…"
  3. Change it to replicas: 3 and the marker goes away.
  4. Compare… opens "Compare Deployment web", with In the cluster on the left and After applying on the right, and 1 change: replicas: 2 becomes replicas: 3. That's the screenshot.
  5. Apply sends the change, and Kuberniq confirms with "Deployment web applied".

What it doesn't do yet

Kuberniq edits the object in the cluster, not the file in your Git repository. If the Deployment comes from Helm, Kustomize or a GitOps tool, the next sync puts back what the repository says, so make the same change there. There's also no Linux build; it runs on macOS and Windows.

Try it

The free license covers personal projects, study, teaching and open source, with the whole app and no account. If you edit manifests in the cluster, we'd like to know what you'd want the editor to check that it doesn't yet.

Download Kuberniq from its page: https://demuxer.dev/kuberniq?utm_source=devto&utm_medium=organic&utm_campaign=kuberniq-desktop&utm_content=dev-to%2Fyaml-editor