Set node_readiness_label default to an empty value. (#204)

Previously, it was set to the lifecycle-status:ready, breaking a
lot of minikube deployments. Also it was not possible befor to run
with this label set to an empty value.

Document the effect of the label in the new section of the
documentation.

pkg/cluster/k8sres.go

@@ -238,6 +238,9 @@ PatroniInitDBParams:
 
 func (c *Cluster) nodeAffinity() *v1.Affinity {
 	matchExpressions := make([]v1.NodeSelectorRequirement, 0)
+	if len(c.OpConfig.NodeReadinessLabel) == 0 {
+		return nil
+	}
 	for k, v := range c.OpConfig.NodeReadinessLabel {
 		matchExpressions = append(matchExpressions, v1.NodeSelectorRequirement{
 			Key:      k,
@@ -431,10 +434,13 @@ func (c *Cluster) generatePodTemplate(
 		ServiceAccountName:            c.OpConfig.ServiceAccountName,
 		TerminationGracePeriodSeconds: &terminateGracePeriodSeconds,
 		Containers:                    []v1.Container{container},
-		Affinity:                      c.nodeAffinity(),
 		Tolerations:                   c.tolerations(tolerationsSpec),
 	}
 
+	if affinity := c.nodeAffinity(); affinity != nil {
+		podSpec.Affinity = affinity
+	}
+
 	if c.OpConfig.ScalyrAPIKey != "" && c.OpConfig.ScalyrImage != "" {
 		podSpec.Containers = append(
 			podSpec.Containers,

pkg/util/config/config.go

@@ -32,7 +32,7 @@ type Resources struct {
 	DefaultCPULimit         string            `name:"default_cpu_limit" default:"3"`
 	DefaultMemoryLimit      string            `name:"default_memory_limit" default:"1Gi"`
 	PodEnvironmentConfigMap string            `name:"pod_environment_configmap" default:""`
-	NodeReadinessLabel      map[string]string `name:"node_readiness_label" default:"lifecycle-status:ready"`
+	NodeReadinessLabel      map[string]string `name:"node_readiness_label" default:""`
 	MaxInstances            int32             `name:"max_instances" default:"-1"`
 	MinInstances            int32             `name:"min_instances" default:"-1"`
 }