Crossplane top command - pods resources utilization implementation

[Piotr1215]

Description of your changes

Initial implementation of the crossplane top command.

This implementation covers running the top command to show resources utilization of crossplane pods:

• crossplane
• functions
• providers

Prerequisites

In order to display metrics, the metrics-server needs to be enabled. Prometheus is not required. Enabling metrics server like so, for example:

 kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
 kubectl patch deployment metrics-server -n kube-system \
  --type='json' \
  -p='[{"op": "add", "path": "/spec/template/spec/containers/0/args/-", "value": "--kubelet-insecure-tls=true"}]'

Running the command

The top command behaves very similarly to the kubectl top pods. It displays CPU and Memory utilization for Crossplane pods. By default the command will search for crossplane pods in the crossplane-system namespace. It's possible to use -n or --namespace flag to look for pods in another namespace.

Running command without flags will default to a table view, sorted by pod type and pod name.

From here, it's easy to use command line utilities like sort awk or sed to manipulate the output.

Running command with -s or --summary flag will add pods summary on top of the table view:

Metrics Server

Before pods can emit metrics it can take a moment for new pods to register, so transient errors like this are possible, just run the command again.

crossplane: error: error adding metrics to pod, check if metrics-server is running or wait until metrics are available for the pod: pods "provider
-aws-052e7b5a5276-96b9888bc-gff49" not found
exit status 1

Partially Implements #5036

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added or updated unit tests.
• Added or updated e2e tests.
• Linked a PR or a docs tracking issue to document this change.
• Added backport release-x.y labels to auto-backport this PR.

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[lsviben]

Did a quick pass, maybe some comments are uneccesary as I know its a WIP, but added them just in case.

[negz]

@Piotr1215 Could you please update the PR description with an example or two, showing what it's like to use the command?

[jbw976]

@Piotr1215 Could you please update the PR description with an example or two, showing what it's like to use the command?

+1 to this as I'm actually having trouble testing this PR myself. I built from your branch/fork, installed Crossplane with --set metrics.enabled=true, but running beta top gives me:

~/dev/go/src/github.com/crossplane/crossplane/_output/bin/darwin_arm64 @c865430c
❯ ./crank beta top -s
crossplane: error: error adding metrics to pod: the server could not find the requested resource (get pods.metrics.k8s.io crossplane-5b8df59d5-9cqt8)

Is there more config I need to do to enable the metrics and get the top command working? 🤔

[Piotr1215]

@negz @jbw976 thank you for the reviews. I have clarified the command usage in PR description and updated command help with examples. In order for the command to work, the metrics server must be enabled.

The error you have seen @jbw976 is a bit unfortunate because it can mean that the metrics server is not enabled (prerequisite not met) or that there are pods that are still registering with the server (transient error).

I've marked as resolved the suggestions that are implemented/fixed. The ones still open have some open questions/comments.

I think adding more tests would also be a good idea :)

[jbw976]

awesome this looks like it got to a clean place to ship initial functionality!! 💪