Resources calculation of a pod with restartable init containers is wrong in kubectl describe nodes

[gjkim42]

What happened?

Resources calculation of a pod with restartable init containers is wrong in kubectl describe nodes
It does not take into account the restartable init containers.

/cc @SergeyKanzhelev @tzneal
/sig node
ref: #115934

What did you expect to happen?

kubectl describe nodes should show the right resource requirement considering restartable init containers.

How can we reproduce it (as minimally and precisely as possible)?

0. Create a cluster enabling SidecarContainers feature gate.

1. Create a pod with a restartable init container

$ cat <<EOF | kubectl apply -f -                                                                  
apiVersion: v1                                                                                    
kind: Pod                                      
metadata:                                                                                                                                                                                                  
  name: sidecar                                                                                                                                                                                            
spec:                                                                                                                                                                                                      
  initContainers:                                                                                                                                                                                          
  - name: init-1                                                                                                                                                                                           
    image: ubuntu                                                                                                                                                                                          
    command:                                                                                                                                                                                               
    - sh                                                                                                                                                                                                   
    - -c                                                                                                                                                                                                   
    - |                                                                                                                                                                                                    
      sleep 1s                                                                                                                                                                                             
    resources:                                                                                                                                                                                             
      limits:                        
        cpu: 100m                                                                                    
        memory: 100Mi                                                                                
  - name: sidecar-1                                                                                                                                                                                        
    image: ubuntu                                                                                                                                                                                          
    command:                                                                                                                                                                                               
    - sh                                                                                                                                                                                                   
    - -c                                                                                                                                                                                                   
    - |                                                                                                                                                                                                    
      sleep 600s                                                                                                                                                                                           
    resources:                                                                                                                                                                                             
      limits:                                                                                        
        cpu: 200m                                                                                                                                                                                          
        memory: 200Mi                                                                                
    restartPolicy: Always                                                                                                                                                                                  
  containers:                                                                                                                                                                                              
  - name: main                                                                                                                                                                                             
    image: ubuntu                                                                                                                                                                                          
    command:                                                                                                                                                                                               
    - sh                                                                                                                                                                                                   
    - -c                                                                                                                                                                                                   
    - |                                                                                                                                                                                                    
      sleep 600s                                                                                                                                                                                           
    resources:                                                                                                                                                                                             
      limits:                                                                                                                                                                                              
        cpu: 300m                                                                                                                                                                                          
        memory: 300Mi                                                                                                                                                                                      
  terminationGracePeriodSeconds: 1                                                                                                                                                                         
EOF                                                                                               
pod/sidecar created

2. wait for the pod is running.

3. kubectl describe node THE_NODE_RUNNING_THAT_POD

$ kubectl describe nodes | grep sidecar -B 3
Non-terminated Pods:          (10 in total)
  Namespace                   Name                                          CPU Requests  CPU Limits  Memory Requests  Memory Limits  Age
  ---------                   ----                                          ------------  ----------  ---------------  -------------  ---
  default                     sidecar                                       300m (2%)     300m (2%)   300Mi (1%)       300Mi (1%)     6m43s

The resource requirement should be 500m CPU, 500Mi memory

Anything else we need to know?

No response

Kubernetes version

$ kubectl version
# paste output here

Cloud provider

OS version

# On Linux:
$ cat /etc/os-release
# paste output here
$ uname -a
# paste output here

# On Windows:
C:\> wmic os get Caption, Version, BuildNumber, OSArchitecture
# paste output here

Install tools

Container runtime (CRI) and version (if applicable)

Related plugins (CNI, CSI, ...) and versions (if applicable)

[tzneal]

/triage accepted
/assign tzneal

[gjkim42]

We can close this now as #119509 has been merged.

/close

[k8s-ci-robot]

@gjkim42: Closing this issue.

In response to this:

We can close this now as #119509 has been merged.

/close

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[Sivakajan-tech]

@gjkim42 @tzneal QQ: Why are only the resources of the restartable init containers expected to be counted, while normal init containers are not included? Your response is highly appreciated.

[gjkim42]

@gjkim42 @tzneal QQ: Why are only the resources of the restartable init containers expected to be counted, while normal init containers are not included? Your response is highly appreciated.

The reason we had excluded the normal init containers was that they temporarily occupy resources and release the resources after the initialization phase. However, the restartable init container occupies the resources for the entire lifecyle of the pod.

See https://kubernetes.io/docs/concepts/workloads/pods/sidecar-containers/ for the detail.
"Restartable init container" is the internal concept to implement the native sidecar container.