feat: use helm genCA to generate a certificate for the mutating web hook if no cert-manager is available (#1780)

README.md

@@ -1574,6 +1574,10 @@ spec:
 
 ### Using without cert-manager
 
+There are two methods of deploying without cert-manager, you can generate your own certificates or rely on helm to generate a CA and certificate each time you update the chart.
+
+#### Using custom certificates
+
 Assuming you are installing in the default namespace, ensure your certificate has SANs:
 
 * `webhook-service.actions-runner-system.svc`
@@ -1601,6 +1605,18 @@ $ helm --upgrade install actions-runner-controller/actions-runner-controller \
   admissionWebHooks.caBundle=${CA_BUNDLE}
 ```
 
+#### Using helm to generate CA and certificates
+
+Set the Helm chart values as follows:
+
+```shell
+$ CA_BUNDLE=$(cat path/to/ca.pem | base64)
+$ helm --upgrade install actions-runner-controller/actions-runner-controller \
+  certManagerEnabled=false
+```
+
+This generates a temporary CA using the helm `genCA` function and issues a certificate for the webhook. Note that this approach rotates the CA and certificate each time `helm install` or `helm upgrade` are run. In effect, this will cause short interruptions to the mutating webhook while the ARC pods stabilize and use the new certificate each time `helm upgrade` is called for the chart. The outage can affect kube-api activity due to the way mutating webhooks are called.
+
 ### Setting up Windows Runners
 
 The main two steps in enabling Windows self-hosted runners are:

charts/actions-runner-controller/templates/webhook_configs.yaml

@@ -1,4 +1,8 @@
-
+{{/*
+We will use a self managed CA if one is not provided by cert-manager
+*/}}
+{{- $ca := genCA "actions-runner-ca" 3650 }}
+{{- $cert := genSignedCert (printf "%s.%s.svc" (include "actions-runner-controller.webhookServiceName" .) .Release.Namespace) nil (list (printf "%s.%s.svc" (include "actions-runner-controller.webhookServiceName" .) .Release.Namespace)) 3650 $ca }}
 ---
 apiVersion: admissionregistration.k8s.io/v1
 kind: MutatingWebhookConfiguration
@@ -20,6 +24,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ quote .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -48,6 +54,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -76,6 +84,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -104,6 +114,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -145,6 +157,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -173,6 +187,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -201,6 +217,8 @@ webhooks:
   clientConfig:
     {{- if .Values.admissionWebHooks.caBundle }}
     caBundle: {{ .Values.admissionWebHooks.caBundle }}
+    {{- else if not .Values.certManagerEnabled }}
+    caBundle: {{ $ca.Cert | b64enc | quote }}
     {{- end }}
     service:
       name: {{ include "actions-runner-controller.webhookServiceName" . }}
@@ -219,3 +237,18 @@ webhooks:
     resources:
     - runnerreplicasets
   sideEffects: None
+{{ if not (or .Values.admissionWebHooks.caBundle .Values.certManagerEnabled) }}
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: {{ include "actions-runner-controller.servingCertName" . }}
+  namespace: {{ .Release.Namespace }}
+  labels:
+    {{- include "actions-runner-controller.labels" . | nindent 4 }}
+type: kubernetes.io/tls
+data:
+  tls.crt: {{ $cert.Cert | b64enc | quote }}
+  tls.key: {{ $cert.Key | b64enc | quote }}
+  ca.crt: {{ $ca.Cert | b64enc | quote }}
+{{- end }}