controller.go

Documentation: sigs.k8s.io/controller-runtime/examples/builtins

     1  /*
     2  Copyright 2018 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 main
    18  
    19  import (
    20  	"context"
    21  	"fmt"
    22  
    23  	appsv1 "k8s.io/api/apps/v1"
    24  	"k8s.io/apimachinery/pkg/api/errors"
    25  	"sigs.k8s.io/controller-runtime/pkg/client"
    26  	"sigs.k8s.io/controller-runtime/pkg/log"
    27  	"sigs.k8s.io/controller-runtime/pkg/reconcile"
    28  )
    29  
    30  // reconcileReplicaSet reconciles ReplicaSets
    31  type reconcileReplicaSet struct {
    32  	// client can be used to retrieve objects from the APIServer.
    33  	client client.Client
    34  }
    35  
    36  // Implement reconcile.Reconciler so the controller can reconcile objects
    37  var _ reconcile.Reconciler = &reconcileReplicaSet{}
    38  
    39  func (r *reconcileReplicaSet) Reconcile(ctx context.Context, request reconcile.Request) (reconcile.Result, error) {
    40  	// set up a convenient log object so we don't have to type request over and over again
    41  	log := log.FromContext(ctx)
    42  
    43  	// Fetch the ReplicaSet from the cache
    44  	rs := &appsv1.ReplicaSet{}
    45  	err := r.client.Get(ctx, request.NamespacedName, rs)
    46  	if errors.IsNotFound(err) {
    47  		log.Error(nil, "Could not find ReplicaSet")
    48  		return reconcile.Result{}, nil
    49  	}
    50  
    51  	if err != nil {
    52  		return reconcile.Result{}, fmt.Errorf("could not fetch ReplicaSet: %+v", err)
    53  	}
    54  
    55  	// Print the ReplicaSet
    56  	log.Info("Reconciling ReplicaSet", "container name", rs.Spec.Template.Spec.Containers[0].Name)
    57  
    58  	// Set the label if it is missing
    59  	if rs.Labels == nil {
    60  		rs.Labels = map[string]string{}
    61  	}
    62  	if rs.Labels["hello"] == "world" {
    63  		return reconcile.Result{}, nil
    64  	}
    65  
    66  	// Update the ReplicaSet
    67  	rs.Labels["hello"] = "world"
    68  	err = r.client.Update(ctx, rs)
    69  	if err != nil {
    70  		return reconcile.Result{}, fmt.Errorf("could not write ReplicaSet: %+v", err)
    71  	}
    72  
    73  	return reconcile.Result{}, nil
    74  }
    75
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