pkg/ansible,pkg/scaffold/ansible; enables leader election for ansible operators

Author: mhrivnak

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - A new command [`operator-sdk migrate`](https://github.com/operator-framework/operator-sdk/blob/master/doc/sdk-cli-reference.md#migrate) which adds a main.go source file and any associated source files for an operator that is not of the "go" type. ([#887](https://github.com/operator-framework/operator-sdk/pull/887) and [#897](https://github.com/operator-framework/operator-sdk/pull/897))
 - New commands [`operator-sdk run ansible`](https://github.com/operator-framework/operator-sdk/blob/master/doc/sdk-cli-reference.md#ansible) and [`operator-sdk run helm`](https://github.com/operator-framework/operator-sdk/blob/master/doc/sdk-cli-reference.md#helm) which run the SDK as ansible  and helm operator processes, respectively. These are intended to be used when running in a Pod inside a cluster. Developers wanting to run their operator locally should continue to use `up local`. ([#887](https://github.com/operator-framework/operator-sdk/pull/887) and [#897](https://github.com/operator-framework/operator-sdk/pull/897))
+- Ansible-based operators have leader election turned on by default. When upgrading, add environment variable `POD_NAME` to your operator's Deployment using the Kubernetes downward API. To see an example, run `operator-sdk new --type=ansible ...` and see file `deploy/operator.yaml`.
 
 ### Changed
 

pkg/ansible/run.go

@@ -15,13 +15,16 @@
 package ansible
 
 import (
+	"context"
 	"os"
 	"runtime"
 
 	aoflags "github.com/operator-framework/operator-sdk/pkg/ansible/flags"
 	"github.com/operator-framework/operator-sdk/pkg/ansible/operator"
 	proxy "github.com/operator-framework/operator-sdk/pkg/ansible/proxy"
 	"github.com/operator-framework/operator-sdk/pkg/k8sutil"
+	"github.com/operator-framework/operator-sdk/pkg/leader"
+	"github.com/operator-framework/operator-sdk/pkg/ready"
 	sdkVersion "github.com/operator-framework/operator-sdk/version"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
@@ -42,6 +45,8 @@ func printVersion() {
 func Run(flags *aoflags.AnsibleOperatorFlags) {
 	logf.SetLogger(logf.ZapLogger(false))
 
+	printVersion()
+
 	namespace, found := os.LookupEnv(k8sutil.WatchNamespaceEnvVar)
 	if found {
 		log.Infof("Watching %v namespace.", namespace)
@@ -58,7 +63,31 @@ func Run(flags *aoflags.AnsibleOperatorFlags) {
 		log.Fatal(err)
 	}
 
-	printVersion()
+	name, found := os.LookupEnv(k8sutil.OperatorNameEnvVar)
+	if !found {
+		log.Fatal("OPERATOR_NAME environment variable not set")
+	}
+	// Become the leader before proceeding
+	err = leader.Become(context.TODO(), name+"-lock")
+	if err != nil {
+		log.Error(err, "")
+		os.Exit(1)
+	}
+
+	// Set ready
+	r := ready.NewFileReady()
+	err = r.Set()
+	if err != nil {
+		log.Error(err, "")
+		os.Exit(1)
+	}
+	defer func() {
+		if err = r.Unset(); err != nil {
+			log.Error(err, "")
+			os.Exit(1)
+		}
+	}()
+
 	done := make(chan error)
 	cMap := proxy.NewControllerMap()
 

pkg/scaffold/ansible/operator.go

@@ -58,6 +58,14 @@ spec:
           - containerPort: 60000
             name: metrics
           imagePullPolicy: Always
+          readinessProbe:
+            exec:
+              command:
+                - stat
+                - /tmp/operator-sdk-ready
+            initialDelaySeconds: 4
+            periodSeconds: 10
+            failureThreshold: 1
           env:
             - name: WATCH_NAMESPACE
               {{- if .IsClusterScoped }}
@@ -67,6 +75,10 @@ spec:
                 fieldRef:
                   fieldPath: metadata.namespace
               {{- end}}
+            - name: POD_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.name
             - name: OPERATOR_NAME
               value: "{{.ProjectName}}"
 `