karmadactl supports top node

[zhzhuang-zju]

What type of PR is this?
/kind feature

What this PR does / why we need it:
karmadactl supports top node

$ karmadactl top node
NAME                    CLUSTER   CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
member1-control-plane   member1   90m          2%     876Mi           5% 
member2-control-plane   member1   90m          2%     876Mi           5% 
member3-control-plane   member1   90m          2%     876Mi           5% 

$ karmadactl top node --clusters=member1
NAME                    CLUSTER   CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
member1-control-plane   member1   90m          2%     876Mi           5% 

Which issue(s) this PR fixes:
Parts of #4217

Special notes for your reviewer:
none

Does this PR introduce a user-facing change?:

`karmadactl`: add new command `top node` to display resource (CPU/memory) usage of nodes in member clusters.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 191 lines in your changes missing coverage. Please review.

Project coverage is 29.52%. Comparing base (6318541) to head (3af667c).

Files	Patch %	Lines
pkg/karmadactl/top/top_node.go	0.00%	143 Missing ⚠️
pkg/karmadactl/top/metrics_printer.go	0.00%	31 Missing ⚠️
pkg/karmadactl/top/metrics_sorter.go	0.00%	16 Missing ⚠️
pkg/karmadactl/top/top.go	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4224      +/-   ##
==========================================
- Coverage   29.67%   29.52%   -0.15%     
==========================================
  Files         632      633       +1     
  Lines       43936    44127     +191     
==========================================
- Hits        13037    13029       -8     
- Misses      29954    30152     +198     
- Partials      945      946       +1     

Flag	Coverage Δ
unittests	29.52% <0.00%> (-0.15%)	⬇️

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[RainbowMango]

Generally looks good to me.

@chaunceyjiang Can you help to take a look? As it's similar to top pods.

[chaunceyjiang]

/assign

[zhzhuang-zju]

kindly ping @chaunceyjiang @RainbowMango

[zhzhuang-zju]

@hulizhe @RainbowMango The previous proposal envisioned that the top pod and top node commands would provide the ability to view the usage of resources in the control plane and member clusters. However, due to the existence of the component metrics-adapter, when the operation scope of the top command is set to karmada, it returns the resources of all member clusters instead, just like:

$ kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-apiserver top pod   
NAME    CPU(cores)   MEMORY(bytes)   
nginx   0m           3Mi             
nginx   0m           2Mi             
nginx   0m           3Mi             
$ kubectl --kubeconfig $HOME/.kube/karmada.config --context karmada-apiserver top node
NAME                    CPU(cores)   CPU%    MEMORY(bytes)   MEMORY%   
member1-control-plane   85m          725Mi   
member2-control-plane   87m          715Mi   
member3-control-plane   94m          786Mi 

So, it would be better to limit the operation-scope of the top command to members.

[RainbowMango]

/lgtm
/approve

It looks great!

# _output/bin/linux/amd64/karmadactl top nodes
NAME                    CLUSTER   CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%   
member1-control-plane   member1   292m         7%     779Mi           4%        
member2-control-plane   member2   98m          2%     772Mi           4%        
member3-control-plane   member3   104m         2%     869Mi           5%        

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RainbowMango

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• pkg/karmadactl/top/OWNERS [RainbowMango]

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