Define sidecars in the operator configuration.

Right now only the name and the docker image can be defined, but with
the help of the pod_environment_configmap parameter arbitrary
environment variables can be passed to the sidecars.

docs/reference/operator_parameters.md

@@ -15,6 +15,11 @@ words.
   your own Spilo image from the [github
   repository](https://github.com/zalando/spilo).
 
+* **sidecars**
+  a map of sidecar names to docker images for the containers to run alongside
+  Spilo. In case of the name conflict with the definition in the cluster
+  manifest the cluster-specific one is preferred.
+
 * **workers**
   number of working routines the operator spawns to process requests to
   create/update/delete/sync clusters concurrently. The default is `4`.

pkg/cluster/k8sres.go

@@ -318,7 +318,7 @@ func (c *Cluster) generatePodTemplate(
 	patroniParameters *spec.Patroni,
 	cloneDescription *spec.CloneDescription,
 	dockerImage *string,
-	sidecars *[]spec.Sidecar,
+	sidecars []spec.Sidecar,
 	customPodEnvVars map[string]string,
 ) (*v1.PodTemplateSpec, error) {
 	spiloConfiguration := c.generateSpiloJSONConfiguration(pgParameters, patroniParameters)
@@ -526,8 +526,8 @@ func (c *Cluster) generatePodTemplate(
 		)
 	}
 
-	if sidecars != nil && len(*sidecars) > 0 {
+	if sidecars != nil && len(sidecars) > 0 {
-		for index, sidecar := range *sidecars {
+		for index, sidecar := range sidecars {
 			sc, err := c.getSidecarContainer(sidecar, index, volumeMounts)
 			if err != nil {
 				return nil, err
@@ -659,7 +659,10 @@ func (c *Cluster) generateStatefulSet(spec *spec.PostgresSpec) (*v1beta1.Statefu
 			customPodEnvVars = cm.Data
 		}
 	}
-	podTemplate, err := c.generatePodTemplate(c.Postgresql.GetUID(), resourceRequirements, resourceRequirementsScalyrSidecar, &spec.Tolerations, &spec.PostgresqlParam, &spec.Patroni, &spec.Clone, &spec.DockerImage, &spec.Sidecars, customPodEnvVars)
+
+	mergedSidecars := c.mergeSidecars(spec.Sidecars)
+
+	podTemplate, err := c.generatePodTemplate(c.Postgresql.GetUID(), resourceRequirements, resourceRequirementsScalyrSidecar, &spec.Tolerations, &spec.PostgresqlParam, &spec.Patroni, &spec.Clone, &spec.DockerImage, mergedSidecars, customPodEnvVars)
 	if err != nil {
 		return nil, fmt.Errorf("could not generate pod template: %v", err)
 	}
@@ -689,6 +692,31 @@ func (c *Cluster) generateStatefulSet(spec *spec.PostgresSpec) (*v1beta1.Statefu
 	return statefulSet, nil
 }
 
+// mergeSidecar merges globally-defined sidecars with those defined in the cluster manifest
+func (c *Cluster) mergeSidecars(sidecars []spec.Sidecar) []spec.Sidecar {
+	globalSidecarsToSkip := map[string]bool{}
+	result := make([]spec.Sidecar, 0)
+
+	for i, sidecar := range sidecars {
+		dockerImage, ok := c.OpConfig.Sidecars[sidecar.Name]
+		if ok {
+			if dockerImage != sidecar.DockerImage {
+				c.logger.Warningf("merging definitions for sidecar %q: "+
+					"ignoring %q in the global scope in favor of %q defined in the cluster",
+					sidecar.Name, dockerImage, sidecar.DockerImage)
+			}
+			globalSidecarsToSkip[sidecar.Name] = true
+		}
+		result = append(result, sidecars[i])
+	}
+	for name, dockerImage := range c.OpConfig.Sidecars {
+		if !globalSidecarsToSkip[name] {
+			result = append(result, spec.Sidecar{Name: name, DockerImage: dockerImage})
+		}
+	}
+	return result
+}
+
 func (c *Cluster) getNumberOfInstances(spec *spec.PostgresSpec) (newcur int32) {
 	min := c.OpConfig.MinInstances
 	max := c.OpConfig.MaxInstances

pkg/util/config/config.go

@@ -71,6 +71,7 @@ type Config struct {
 	WatchedNamespace string            `name:"watched_namespace"`    // special values: "*" means 'watch all namespaces', the empty string "" means 'watch a namespace where operator is deployed to'
 	EtcdHost         string            `name:"etcd_host" default:""` // special values: the empty string "" means Patroni will use k8s as a DCS
 	DockerImage      string            `name:"docker_image" default:"registry.opensource.zalan.do/acid/spilo-cdp-10:1.4-p8"`
+	Sidecars         map[string]string `name:"sidecars"`
 	// default name `operator` enables backward compatibility with the older ServiceAccountName field
 	PodServiceAccountName string `name:"pod_service_account_name" default:"operator"`
 	// value of this string must be valid JSON or YAML; see initPodServiceAccount