Add operator deployment readiness probe (zalando#1874)

* Add operator deployment readiness probe

Author: dmvolod

charts/postgres-operator/templates/deployment.yaml

@@ -57,6 +57,14 @@ spec:
 {{ toYaml .Values.resources | indent 10 }}
         securityContext:
 {{ toYaml .Values.securityContext | indent 10 }}
+        {{- if .Values.readinessProbe }}
+        readinessProbe:
+          httpGet:
+            path: /readyz
+            port: {{ .Values.configLoggingRestApi.api_port }}
+          initialDelaySeconds: {{ .Values.readinessProbe.initialDelaySeconds }}
+          periodSeconds: {{ .Values.readinessProbe.periodSeconds }}
+        {{- end }}
       {{- if .Values.imagePullSecrets }}
       imagePullSecrets:
 {{ toYaml .Values.imagePullSecrets | indent 8 }}

charts/postgres-operator/values.yaml

@@ -470,6 +470,11 @@ securityContext:
   readOnlyRootFilesystem: true
   allowPrivilegeEscalation: false
 
+# Allow to setup operator Deployment readiness probe
+readinessProbe:
+  initialDelaySeconds: 5
+  periodSeconds: 10
+
 # Affinity for pod assignment
 # Ref: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity
 affinity: {}

pkg/apiserver/apiserver.go

@@ -12,7 +12,6 @@ import (
 	"time"
 
 	"github.com/sirupsen/logrus"
-
 	"github.com/zalando/postgres-operator/pkg/cluster"
 	"github.com/zalando/postgres-operator/pkg/spec"
 	"github.com/zalando/postgres-operator/pkg/util"
@@ -87,6 +86,7 @@ func New(controller controllerInformer, port int, logger *logrus.Logger) *Server
 	mux.Handle("/debug/pprof/trace", http.HandlerFunc(pprof.Trace))
 
 	mux.Handle("/status/", http.HandlerFunc(s.controllerStatus))
+	mux.Handle("/readyz/", http.HandlerFunc(s.controllerReady))
 	mux.Handle("/config/", http.HandlerFunc(s.operatorConfig))
 
 	mux.HandleFunc("/clusters/", s.clusters)
@@ -155,6 +155,10 @@ func (s *Server) controllerStatus(w http.ResponseWriter, req *http.Request) {
 	s.respond(s.controller.GetStatus(), nil, w)
 }
 
+func (s *Server) controllerReady(w http.ResponseWriter, req *http.Request) {
+	s.respond("OK", nil, w)
+}
+
 func (s *Server) operatorConfig(w http.ResponseWriter, req *http.Request) {
 	s.respond(map[string]interface{}{
 		"controller": s.controller.GetConfig(),