From c30f1984e418bc12953bd967fcc8dd2598173a65 Mon Sep 17 00:00:00 2001
From: Karl Lyons <7.lyonsy@gmail.com>
Date: Tue, 2 Apr 2024 13:26:07 -0400
Subject: [PATCH] feat(argo-workflows): Add the ability to use headless service
 for workflow controller (#2620)

---
 charts/argo-workflows/Chart.yaml                              | 4 ++--
 charts/argo-workflows/README.md                               | 1 +
 .../templates/controller/workflow-controller-service.yaml     | 3 +++
 charts/argo-workflows/values.yaml                             | 2 ++
 4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/charts/argo-workflows/Chart.yaml b/charts/argo-workflows/Chart.yaml
index 6223ffc6..0243bcd7 100644
--- a/charts/argo-workflows/Chart.yaml
+++ b/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
diff --git a/charts/argo-workflows/README.md b/charts/argo-workflows/README.md
index 3a387546..e8d99b6d 100644
--- a/charts/argo-workflows/README.md
+++ b/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 |
diff --git a/charts/argo-workflows/templates/controller/workflow-controller-service.yaml b/charts/argo-workflows/templates/controller/workflow-controller-service.yaml
index 51362c4f..0cd8a75b 100644
--- a/charts/argo-workflows/templates/controller/workflow-controller-service.yaml
+++ b/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 }}
diff --git a/charts/argo-workflows/values.yaml b/charts/argo-workflows/values.yaml
index 3c361c9c..89fa1753 100644
--- a/charts/argo-workflows/values.yaml
+++ b/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: []