feat(argo-workflows): Add the ability to use headless service for workflow controller (#2620)

charts/argo-workflows/Chart.yaml

@@ -3,7 +3,7 @@ appVersion: v3.5.5
 name: argo-workflows
 description: A Helm chart for Argo Workflows
 type: application
-version: 0.41.0
+version: 0.41.1
 icon: https://argo-workflows.readthedocs.io/en/stable/assets/logo.png
 home: https://github.com/argoproj/argo-helm
 sources:
@@ -17,4 +17,4 @@ annotations:
     url: https://argoproj.github.io/argo-helm/pgp_keys.asc
   artifacthub.io/changes: |
     - kind: added
-      description: Check Prometheus CRDs are available before creating Service Monitor resource(s)
+      description: Add the ability to use a headless service for the workflow controller

charts/argo-workflows/README.md

@@ -170,6 +170,7 @@ Fields to note:
 | controller.logging.globallevel | string | `"0"` | Set the glog logging level |
 | controller.logging.level | string | `"info"` | Set the logging level (one of: `debug`, `info`, `warn`, `error`) |
 | controller.metricsConfig.enabled | bool | `false` | Enables prometheus metrics server |
+| controller.metricsConfig.headlessService | bool | `false` | Flag to enable headless service |
 | controller.metricsConfig.ignoreErrors | bool | `false` | Flag that instructs prometheus to ignore metric emission errors. |
 | controller.metricsConfig.metricRelabelings | list | `[]` | ServiceMonitor metric relabel configs to apply to samples before ingestion |
 | controller.metricsConfig.metricsTTL | string | `""` | How often custom metrics are cleared from memory |

charts/argo-workflows/templates/controller/workflow-controller-service.yaml

@@ -32,6 +32,9 @@ spec:
     {{- include "argo-workflows.selectorLabels" (dict "context" . "name" .Values.controller.name) | nindent 4 }}
   sessionAffinity: None
   type: {{ .Values.controller.serviceType }}
+  {{- if and (eq .Values.controller.serviceType "ClusterIP") .Values.controller.metricsConfig.headlessService }}
+  clusterIP: None
+  {{- end }}
   {{- if and (eq .Values.controller.serviceType "LoadBalancer") .Values.controller.loadBalancerSourceRanges }}
   loadBalancerSourceRanges:
     {{- toYaml .Values.controller.loadBalancerSourceRanges | nindent 4 }}

charts/argo-workflows/values.yaml

@@ -135,6 +135,8 @@ controller:
     servicePort: 8080
     # -- Service metrics port name
     servicePortName: metrics
+    # -- Flag to enable headless service
+    headlessService: false
     # -- ServiceMonitor relabel configs to apply to samples before scraping
     ## Ref: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#relabelconfig
     relabelings: []