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main.go
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main.go
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package main
import (
"context"
"flag"
"fmt"
"os"
"path/filepath"
"strings"
"time"
"github.com/mongodb/mongo-go-driver/x/bsonx"
"github.com/mongodb/mongo-go-driver/x/network/address"
"github.com/mongodb/mongo-go-driver/x/network/command"
"github.com/mongodb/mongo-go-driver/x/network/connection"
"github.com/mongodb/mongo-go-driver/x/network/wiremessage"
"github.com/sirupsen/logrus"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/clientcmd"
)
type Config struct {
LabelSelector string
Namespace string
Address string
LabelAll bool
LogLevel logrus.Level
}
type Labeler struct {
Config *Config
K8scli *kubernetes.Clientset
}
func New() (*Labeler, error) {
config, err := getConfigFromEnvironment()
if err != nil {
return nil, err
}
k8scli, err := getKubeClientSet()
if err != nil {
return nil, err
}
return &Labeler{
Config: config,
K8scli: k8scli,
}, nil
}
func (l *Labeler) setPrimaryLabel() error {
primary, err := l.getMongoPrimary()
if err != nil {
return err
}
listOptions := metav1.ListOptions{
LabelSelector: l.Config.LabelSelector,
}
pods, err := l.K8scli.CoreV1().Pods(l.Config.Namespace).List(context.Background(), listOptions)
if err != nil {
return err
}
var found bool
logrus.Debugf("Found %d pods", len(pods.Items))
for _, pod := range pods.Items {
name := pod.GetName()
if name == primary {
if pod.Labels["primary"] != "true" {
logrus.Infof("Setting primary to true for pod %s", name)
}
pod.Labels["primary"] = "true"
found = true
} else {
if l.Config.LabelAll == true {
if pod.Labels["primary"] != "false" {
logrus.Infof("Setting primary to false for pod %s", name)
}
pod.Labels["primary"] = "false"
} else {
delete(pod.Labels, "primary")
}
}
logrus.Debugf("Setting labels %v", pod.Labels)
_, err := l.K8scli.CoreV1().Pods(l.Config.Namespace).Update(context.Background(), &pod, metav1.UpdateOptions{})
if err != nil {
return err
}
}
if !found {
return fmt.Errorf("primary not found")
}
return nil
}
func getConfigFromEnvironment() (*Config, error) {
var l string
var ok bool
if l, ok = os.LookupEnv("LABEL_SELECTOR"); !ok {
return nil, fmt.Errorf("please export LABEL_SELECTOR")
}
config := &Config{
LabelSelector: l,
Namespace: "default",
Address: "localhost:27017",
LabelAll: false,
LogLevel: logrus.InfoLevel,
}
if l, ok = os.LookupEnv("NAMESPACE"); ok {
config.Namespace = l
}
if l, ok = os.LookupEnv("MONGO_ADDRESS"); ok {
config.Address = l
}
if _, ok = os.LookupEnv("LABEL_ALL"); ok {
config.LabelAll = true
}
if _, ok = os.LookupEnv("DEBUG"); ok {
config.LogLevel = logrus.DebugLevel
}
return config, nil
}
func getKubeClientSet() (*kubernetes.Clientset, error) {
if _, ok := os.LookupEnv("KUBERNETES_SERVICE_HOST"); ok {
config, err := rest.InClusterConfig()
if err != nil {
return nil, err
}
return kubernetes.NewForConfig(config)
}
var kubeconfig *string
if home := homeDir(); home != "" {
kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
} else {
kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
}
flag.Parse()
// use the current context in kubeconfig
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
if err != nil {
return nil, err
}
return kubernetes.NewForConfig(config)
}
func homeDir() string {
if h := os.Getenv("HOME"); h != "" {
return h
}
return os.Getenv("USERPROFILE") // windows
}
func (l *Labeler) getMongoPrimary() (string, error) {
ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
defer cancel()
var addr address.Address
addr = address.Address(l.Config.Address)
c, _, err := connection.New(ctx, addr)
if err != nil {
return "", err
}
defer func(c connection.Connection) {
err := c.Close()
if err != nil {
_ = fmt.Errorf("not posiblie to close connection")
}
}(c)
isMaster, err := (&command.IsMaster{}).Encode()
err = c.WriteWireMessage(ctx, isMaster)
if err != nil {
return "", err
}
wm, err := c.ReadWireMessage(ctx)
if err != nil {
return "", err
}
reply := wm.(wiremessage.Reply)
doc, err := reply.GetMainDocument()
var hosts bsonx.Arr
var ok bool
if hosts, ok = doc.Lookup("hosts").ArrayOK(); !ok {
return "", fmt.Errorf("no hosts found for replica")
}
logrus.Debugf("Hosts %s", hosts)
if primaryHost, ok := doc.Lookup("primary").StringValueOK(); ok {
primary := strings.Split(primaryHost, ".")[0]
if len(primary) != 0 {
return primary, nil
}
}
return "", fmt.Errorf("can't find primary server")
}
func main() {
labeler, err := New()
if err != nil {
logrus.Fatal(err)
}
logrus.SetLevel(labeler.Config.LogLevel)
logrus.Infof("Setting logging level to %s", labeler.Config.LogLevel.String())
ticker := time.NewTicker(5 * time.Second).C
done := make(chan bool)
for {
select {
case <-ticker:
err := labeler.setPrimaryLabel()
if err != nil {
logrus.Error(err)
}
case <-done:
logrus.Info("Done")
return
}
}
}