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leader.go
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leader.go
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// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2016-present Datadog, Inc.
package leader
import (
"context"
"encoding/json"
"fmt"
"github.com/DataDog/datadog-operator/pkg/plugin/common"
"github.com/spf13/cobra"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
"k8s.io/cli-runtime/pkg/genericclioptions"
"sigs.k8s.io/controller-runtime/pkg/client"
)
var leaderExample = `
# get the pod name of the datadog cluster agent leader
%[1]s leader
`
// options provides information required by clusteragent leader command.
type options struct {
genericclioptions.IOStreams
common.Options
args []string
}
type leaderResponse struct {
HolderIdentity string `json:"holderIdentity"`
}
// newOptions provides an instance of options with default values.
func newOptions(streams genericclioptions.IOStreams) *options {
o := &options{
IOStreams: streams,
}
o.SetConfigFlags()
return o
}
// New provides a cobra command wrapping options for "leader" sub command.
func New(streams genericclioptions.IOStreams) *cobra.Command {
o := newOptions(streams)
cmd := &cobra.Command{
Use: "leader",
Short: "Get Datadog Cluster Agent leader",
Example: fmt.Sprintf(leaderExample, "kubectl datadog clusteragent"),
SilenceUsage: true,
RunE: func(c *cobra.Command, args []string) error {
if err := o.complete(c, args); err != nil {
return err
}
if err := o.validate(); err != nil {
return err
}
return o.run(c)
},
}
o.ConfigFlags.AddFlags(cmd.Flags())
return cmd
}
// complete sets all information required for processing the command.
func (o *options) complete(cmd *cobra.Command, args []string) error {
o.args = args
return o.Init(cmd)
}
// validate ensures that all required arguments and flag values are provided.
func (o *options) validate() error {
return nil
}
// run runs the leader command.
func (o *options) run(cmd *cobra.Command) error {
// FIXME: Support multiple leader election config maps.
cmName := "datadog-leader-election"
// Get the config map holding the leader identity.
cm := &corev1.ConfigMap{}
err := o.Client.Get(context.TODO(), client.ObjectKey{Namespace: o.UserNamespace, Name: cmName}, cm)
if err != nil && apierrors.IsNotFound(err) {
return fmt.Errorf("config map %s/%s not found", o.UserNamespace, cmName)
} else if err != nil {
return fmt.Errorf("unable to get leader election config map: %w", err)
}
// Get leader from annotations.
annotations := cm.GetAnnotations()
leaderInfo, found := annotations["control-plane.alpha.kubernetes.io/leader"]
if !found {
return fmt.Errorf("couldn't find leader annotation on %s config map", cmName)
}
leader := leaderResponse{}
if err := json.Unmarshal([]byte(leaderInfo), &leader); err != nil {
return fmt.Errorf("couldn't unmarshal leader annotation: %w", err)
}
cmd.Println("The Pod name of the Cluster Agent is:", leader.HolderIdentity)
return nil
}