k8s.io/kubernetes@v1.31.0-alpha.0.0.20240520171757-56147500dadc/pkg/kubelet/images/puller.go (about)

     1  /*
     2  Copyright 2016 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package images
    18  
    19  import (
    20  	"context"
    21  	"time"
    22  
    23  	v1 "k8s.io/api/core/v1"
    24  	"k8s.io/apimachinery/pkg/util/wait"
    25  	runtimeapi "k8s.io/cri-api/pkg/apis/runtime/v1"
    26  	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
    27  )
    28  
    29  type pullResult struct {
    30  	imageRef     string
    31  	imageSize    uint64
    32  	err          error
    33  	pullDuration time.Duration
    34  }
    35  
    36  type imagePuller interface {
    37  	pullImage(context.Context, kubecontainer.ImageSpec, []v1.Secret, chan<- pullResult, *runtimeapi.PodSandboxConfig)
    38  }
    39  
    40  var _, _ imagePuller = &parallelImagePuller{}, &serialImagePuller{}
    41  
    42  type parallelImagePuller struct {
    43  	imageService kubecontainer.ImageService
    44  	tokens       chan struct{}
    45  }
    46  
    47  func newParallelImagePuller(imageService kubecontainer.ImageService, maxParallelImagePulls *int32) imagePuller {
    48  	if maxParallelImagePulls == nil || *maxParallelImagePulls < 1 {
    49  		return &parallelImagePuller{imageService, nil}
    50  	}
    51  	return &parallelImagePuller{imageService, make(chan struct{}, *maxParallelImagePulls)}
    52  }
    53  
    54  func (pip *parallelImagePuller) pullImage(ctx context.Context, spec kubecontainer.ImageSpec, pullSecrets []v1.Secret, pullChan chan<- pullResult, podSandboxConfig *runtimeapi.PodSandboxConfig) {
    55  	go func() {
    56  		if pip.tokens != nil {
    57  			pip.tokens <- struct{}{}
    58  			defer func() { <-pip.tokens }()
    59  		}
    60  		startTime := time.Now()
    61  		imageRef, err := pip.imageService.PullImage(ctx, spec, pullSecrets, podSandboxConfig)
    62  		var size uint64
    63  		if err == nil && imageRef != "" {
    64  			// Getting the image size with best effort, ignoring the error.
    65  			size, _ = pip.imageService.GetImageSize(ctx, spec)
    66  		}
    67  		pullChan <- pullResult{
    68  			imageRef:     imageRef,
    69  			imageSize:    size,
    70  			err:          err,
    71  			pullDuration: time.Since(startTime),
    72  		}
    73  	}()
    74  }
    75  
    76  // Maximum number of image pull requests than can be queued.
    77  const maxImagePullRequests = 10
    78  
    79  type serialImagePuller struct {
    80  	imageService kubecontainer.ImageService
    81  	pullRequests chan *imagePullRequest
    82  }
    83  
    84  func newSerialImagePuller(imageService kubecontainer.ImageService) imagePuller {
    85  	imagePuller := &serialImagePuller{imageService, make(chan *imagePullRequest, maxImagePullRequests)}
    86  	go wait.Until(imagePuller.processImagePullRequests, time.Second, wait.NeverStop)
    87  	return imagePuller
    88  }
    89  
    90  type imagePullRequest struct {
    91  	ctx              context.Context
    92  	spec             kubecontainer.ImageSpec
    93  	pullSecrets      []v1.Secret
    94  	pullChan         chan<- pullResult
    95  	podSandboxConfig *runtimeapi.PodSandboxConfig
    96  }
    97  
    98  func (sip *serialImagePuller) pullImage(ctx context.Context, spec kubecontainer.ImageSpec, pullSecrets []v1.Secret, pullChan chan<- pullResult, podSandboxConfig *runtimeapi.PodSandboxConfig) {
    99  	sip.pullRequests <- &imagePullRequest{
   100  		ctx:              ctx,
   101  		spec:             spec,
   102  		pullSecrets:      pullSecrets,
   103  		pullChan:         pullChan,
   104  		podSandboxConfig: podSandboxConfig,
   105  	}
   106  }
   107  
   108  func (sip *serialImagePuller) processImagePullRequests() {
   109  	for pullRequest := range sip.pullRequests {
   110  		startTime := time.Now()
   111  		imageRef, err := sip.imageService.PullImage(pullRequest.ctx, pullRequest.spec, pullRequest.pullSecrets, pullRequest.podSandboxConfig)
   112  		var size uint64
   113  		if err == nil && imageRef != "" {
   114  			// Getting the image size with best effort, ignoring the error.
   115  			size, _ = sip.imageService.GetImageSize(pullRequest.ctx, pullRequest.spec)
   116  		}
   117  		pullRequest.pullChan <- pullResult{
   118  			imageRef:  imageRef,
   119  			imageSize: size,
   120  			err:       err,
   121  			// Note: pullDuration includes credential resolution and getting the image size.
   122  			pullDuration: time.Since(startTime),
   123  		}
   124  	}
   125  }