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main.go
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main.go
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package main
import (
"encoding/json"
"errors"
"log"
"os"
"strconv"
"sync"
"time"
apps "k8s.io/api/apps/v1beta2"
core "k8s.io/api/core/v1"
meta "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/types"
"k8s.io/apimachinery/pkg/util/strategicpatch"
"k8s.io/apimachinery/pkg/watch"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
)
type ChangeType struct {
Type string
Name string
}
type Deployment struct {
Name string
Options meta.GetOptions
}
var (
namespace = "default"
changeTimers = map[ChangeType]*time.Timer{}
updateTimers = map[Deployment]*time.Timer{}
delay = time.Duration(5) * time.Second
client *kubernetes.Clientset
config *rest.Config
)
func main() {
ns := os.Getenv("CONFIGMASTER_NAMESPACE")
if ns != "" {
namespace = ns
}
d := os.Getenv("CONFIGMASTER_DELAY")
if d != "" {
di, err := strconv.Atoi(d)
if err != nil {
panic(err)
}
delay = time.Duration(di) * time.Second
}
var err error
if os.Getenv("KUBERNETES_SERVICE_HOST") != "" && os.Getenv("KUBERNETES_SERVICE_PORT") != "" {
config, err = rest.InClusterConfig()
if err != nil {
panic(err)
}
} else {
if os.Getenv("CONFIGMASTER_HOST") == "" {
panic(errors.New("Must export CONFIGMASTER_HOST"))
}
config = &rest.Config{
Host: os.Getenv("CONFIGMASTER_HOST"),
}
}
wg := sync.WaitGroup{}
wg.Add(1)
client = kubernetes.NewForConfigOrDie(config)
log.Printf("configmaster connecting to %s listening on namespace %s with %.0fs delay", config.Host, namespace, delay.Seconds())
filterFunc := func(in watch.Event) (watch.Event, bool) {
return in, in.Type == "MODIFIED"
}
go func() {
configmaps, err := client.CoreV1().ConfigMaps(namespace).Watch(meta.ListOptions{})
if err != nil {
panic(err)
}
for event := range watch.Filter(configmaps, filterFunc).ResultChan() {
configmap, _ := event.Object.(*core.ConfigMap)
delayedUpdate(ChangeType{
Type: "ConfigMap",
Name: configmap.ObjectMeta.Name,
})
}
}()
go func() {
secrets, err := client.CoreV1().Secrets(namespace).Watch(meta.ListOptions{})
if err != nil {
panic(err)
}
for event := range watch.Filter(secrets, filterFunc).ResultChan() {
secret, _ := event.Object.(*core.Secret)
delayedUpdate(ChangeType{
Type: "Secret",
Name: secret.ObjectMeta.Name,
})
}
}()
wg.Wait()
}
func delayedUpdate(change ChangeType) {
if timer, ok := changeTimers[change]; ok {
log.Printf("saw change to %s %s, resetting delay", change.Type, change.Name)
timer.Reset(delay)
} else {
log.Printf("saw change to %s %s, starting countdown", change.Type, change.Name)
changeTimers[change] = time.AfterFunc(delay, func() {
delete(changeTimers, change)
findAndQueueDeployments(change)
})
}
}
func findAndQueueDeployments(change ChangeType) {
deployments, err := client.AppsV1beta2().Deployments(namespace).List(meta.ListOptions{})
if err != nil {
panic(err)
}
deploymentLoop:
for _, deployment := range deployments.Items {
for _, container := range deployment.Spec.Template.Spec.Containers {
for _, env := range container.EnvFrom {
if change.Type == "ConfigMap" && env.ConfigMapRef != nil && env.ConfigMapRef.Name == change.Name {
queueDeployment(deployment)
continue deploymentLoop
}
if change.Type == "Secret" && env.SecretRef != nil && env.SecretRef.Name == change.Name {
queueDeployment(deployment)
continue deploymentLoop
}
}
for _, env := range container.Env {
if change.Type == "ConfigMap" && env.ValueFrom != nil && env.ValueFrom.ConfigMapKeyRef != nil && env.ValueFrom.ConfigMapKeyRef.Name == change.Name {
queueDeployment(deployment)
continue deploymentLoop
}
if change.Type == "Secret" && env.ValueFrom != nil && env.ValueFrom.SecretKeyRef != nil && env.ValueFrom.SecretKeyRef.Name == change.Name {
queueDeployment(deployment)
continue deploymentLoop
}
}
}
}
}
func queueDeployment(deployment apps.Deployment) {
dep := Deployment{
Name: deployment.Name,
Options: meta.GetOptions{
ResourceVersion: deployment.ObjectMeta.ResourceVersion,
},
}
if timer, ok := updateTimers[dep]; ok {
log.Printf("resetting timer on queued update to deployment %s", deployment.Name)
timer.Reset(delay)
} else {
log.Printf("queuing update to deployment %s", deployment.Name)
updateTimers[dep] = time.AfterFunc(delay, func() {
delete(updateTimers, dep)
patchDeployment(dep)
})
}
}
func patchDeployment(deployment Deployment) {
dep, err := client.AppsV1beta2().Deployments(namespace).Get(deployment.Name, deployment.Options)
if err != nil {
log.Printf("error retrieving deployment %s: %+v", deployment.Name, err)
return
}
current, err := json.Marshal(dep)
if err != nil {
log.Printf("error marshaling deployment %s: %+v", dep.Name, err)
return
}
if dep.Annotations == nil {
dep.Annotations = map[string]string{}
}
if dep.Spec.Template.Annotations == nil {
dep.Spec.Template.Annotations = map[string]string{}
}
now := time.Now().Format(time.RFC3339)
dep.Annotations["configmaster/last.update"] = now
dep.Spec.Template.Annotations["configmaster/last.update"] = now
updated, err := json.Marshal(dep)
if err != nil {
log.Printf("error marshaling deployment %s: %+v", dep.Name, err)
return
}
patch, err := strategicpatch.CreateTwoWayMergePatch(current, updated, apps.Deployment{})
if err != nil {
log.Printf("error generating patch for deployment %s: %+v", dep.Name, err)
return
}
_, err = client.AppsV1beta2().Deployments(namespace).Patch(dep.Name, types.StrategicMergePatchType, patch)
if err != nil {
log.Printf("error patching deployment %s: %+v", dep.Name, err)
return
}
log.Printf("patched deployment %s", dep.Name)
}