admission.go

Documentation: k8s.io/kubernetes/plugin/pkg/admission/defaulttolerationseconds

     1  /*
     2  Copyright 2017 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 defaulttolerationseconds
    18  
    19  import (
    20  	"context"
    21  	"flag"
    22  	"fmt"
    23  	"io"
    24  
    25  	v1 "k8s.io/api/core/v1"
    26  	"k8s.io/apimachinery/pkg/api/errors"
    27  	"k8s.io/apiserver/pkg/admission"
    28  	api "k8s.io/kubernetes/pkg/apis/core"
    29  )
    30  
    31  // PluginName indicates name of admission plugin.
    32  const PluginName = "DefaultTolerationSeconds"
    33  
    34  var (
    35  	defaultNotReadyTolerationSeconds = flag.Int64("default-not-ready-toleration-seconds", 300,
    36  		"Indicates the tolerationSeconds of the toleration for notReady:NoExecute"+
    37  			" that is added by default to every pod that does not already have such a toleration.")
    38  
    39  	defaultUnreachableTolerationSeconds = flag.Int64("default-unreachable-toleration-seconds", 300,
    40  		"Indicates the tolerationSeconds of the toleration for unreachable:NoExecute"+
    41  			" that is added by default to every pod that does not already have such a toleration.")
    42  
    43  	notReadyToleration = api.Toleration{
    44  		Key:               v1.TaintNodeNotReady,
    45  		Operator:          api.TolerationOpExists,
    46  		Effect:            api.TaintEffectNoExecute,
    47  		TolerationSeconds: defaultNotReadyTolerationSeconds,
    48  	}
    49  
    50  	unreachableToleration = api.Toleration{
    51  		Key:               v1.TaintNodeUnreachable,
    52  		Operator:          api.TolerationOpExists,
    53  		Effect:            api.TaintEffectNoExecute,
    54  		TolerationSeconds: defaultUnreachableTolerationSeconds,
    55  	}
    56  )
    57  
    58  // Register registers a plugin
    59  func Register(plugins *admission.Plugins) {
    60  	plugins.Register(PluginName, func(config io.Reader) (admission.Interface, error) {
    61  		return NewDefaultTolerationSeconds(), nil
    62  	})
    63  }
    64  
    65  // Plugin contains the client used by the admission controller
    66  // It will add default tolerations for every pod
    67  // that tolerate taints `notReady:NoExecute` and `unreachable:NoExecute`,
    68  // with tolerationSeconds of 300s.
    69  // If the pod already specifies a toleration for taint `notReady:NoExecute`
    70  // or `unreachable:NoExecute`, the plugin won't touch it.
    71  type Plugin struct {
    72  	*admission.Handler
    73  }
    74  
    75  var _ admission.MutationInterface = &Plugin{}
    76  
    77  // NewDefaultTolerationSeconds creates a new instance of the DefaultTolerationSeconds admission controller
    78  func NewDefaultTolerationSeconds() *Plugin {
    79  	return &Plugin{
    80  		Handler: admission.NewHandler(admission.Create, admission.Update),
    81  	}
    82  }
    83  
    84  // Admit makes an admission decision based on the request attributes
    85  func (p *Plugin) Admit(ctx context.Context, attributes admission.Attributes, o admission.ObjectInterfaces) (err error) {
    86  	if attributes.GetResource().GroupResource() != api.Resource("pods") {
    87  		return nil
    88  	}
    89  
    90  	if len(attributes.GetSubresource()) > 0 {
    91  		// only run the checks below on pods proper and not subresources
    92  		return nil
    93  	}
    94  
    95  	pod, ok := attributes.GetObject().(*api.Pod)
    96  	if !ok {
    97  		return errors.NewBadRequest(fmt.Sprintf("expected *api.Pod but got %T", attributes.GetObject()))
    98  	}
    99  
   100  	tolerations := pod.Spec.Tolerations
   101  
   102  	toleratesNodeNotReady := false
   103  	toleratesNodeUnreachable := false
   104  	for _, toleration := range tolerations {
   105  		if (toleration.Key == v1.TaintNodeNotReady || len(toleration.Key) == 0) &&
   106  			(toleration.Effect == api.TaintEffectNoExecute || len(toleration.Effect) == 0) {
   107  			toleratesNodeNotReady = true
   108  		}
   109  
   110  		if (toleration.Key == v1.TaintNodeUnreachable || len(toleration.Key) == 0) &&
   111  			(toleration.Effect == api.TaintEffectNoExecute || len(toleration.Effect) == 0) {
   112  			toleratesNodeUnreachable = true
   113  		}
   114  	}
   115  
   116  	if !toleratesNodeNotReady {
   117  		pod.Spec.Tolerations = append(pod.Spec.Tolerations, notReadyToleration)
   118  	}
   119  
   120  	if !toleratesNodeUnreachable {
   121  		pod.Spec.Tolerations = append(pod.Spec.Tolerations, unreachableToleration)
   122  	}
   123  
   124  	return nil
   125  }
   126
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