operator: modified prometheus wget probe when listenLocal

When using prometheus with listenLocal=true the wget probe in the pod
failed because the created download file prenvents further successfull
wget runs.
Using /dev/null for the wget output file fixes that.

Fixes #2921

pkg/prometheus/statefulset.go

@@ -616,7 +616,7 @@ func makeStatefulSetSpec(p monitoringv1.Prometheus, c *Config, ruleConfigMapName
 		fmt.Sprintf("--config-envsubst-file=%s", path.Join(confOutDir, configEnvsubstFilename)),
 	}
 
-	const localProbe = `if [ -x "$(command -v curl)" ]; then curl %s; elif [ -x "$(command -v wget)" ]; then wget -q %s; else exit 1; fi`
+	const localProbe = `if [ -x "$(command -v curl)" ]; then curl %s; elif [ -x "$(command -v wget)" ]; then wget -q -O /dev/null %s; else exit 1; fi`
 
 	var livenessProbeHandler v1.Handler
 	var readinessProbeHandler v1.Handler

pkg/prometheus/statefulset_test.go

@@ -406,7 +406,7 @@ func TestListenLocal(t *testing.T) {
 				Command: []string{
 					`sh`,
 					`-c`,
-					`if [ -x "$(command -v curl)" ]; then curl http://localhost:9090/-/ready; elif [ -x "$(command -v wget)" ]; then wget -q http://localhost:9090/-/ready; else exit 1; fi`,
+					`if [ -x "$(command -v curl)" ]; then curl http://localhost:9090/-/ready; elif [ -x "$(command -v wget)" ]; then wget -q -O /dev/null http://localhost:9090/-/ready; else exit 1; fi`,
 				},
 			},
 		},
@@ -425,7 +425,7 @@ func TestListenLocal(t *testing.T) {
 				Command: []string{
 					`sh`,
 					`-c`,
-					`if [ -x "$(command -v curl)" ]; then curl http://localhost:9090/-/healthy; elif [ -x "$(command -v wget)" ]; then wget -q http://localhost:9090/-/healthy; else exit 1; fi`,
+					`if [ -x "$(command -v curl)" ]; then curl http://localhost:9090/-/healthy; elif [ -x "$(command -v wget)" ]; then wget -q -O /dev/null http://localhost:9090/-/healthy; else exit 1; fi`,
 				},
 			},
 		},