Readiness and liveness probing on a multi-container service

Review feedback for SRVKS-1220

Author: ochromy

knative-serving/config-applications/multi-container-support-for-serving.adoc

@@ -8,3 +8,6 @@ You can deploy a multi-container pod by using a single Knative service. This met
 
 // Multi-container support
 include::modules/serverless-configuring-multi-container-service.adoc[leveloffset=+1]
+
+// Probing a multi-container service
+include::modules/serverless-probing-multi-container-service.adoc[leveloffset=+1]

modules/serverless-probing-multi-container-service.adoc

@@ -0,0 +1,67 @@
+// Module included in the following assemblies:
+//
+// * serverless/knative-serving/config-applications/multi-container-support-for-serving.adoc
+
+
+:_content-type: PROCEDURE
+[id="serverless-probing-multi-container-service_{context}"]
+= Probing a multi-container service
+
+
+You can specify readiness and liveness probes for multiple containers. This feature is not enabled by default and you must configure it using the `KnativeServing` custom resource (CR).
+
+
+.Procedure
+
+
+. Configure multi-container probing for your service by enabling the `multi-container-probing` feature in the `KnativeServing` CR.
++
+.Multi-container probing configuration
+[source,yaml]
+----
+...
+spec:
+  config:
+    features:
+      "multi-container-probing": enabled <1>
+...
+----
+<1> Enabled multi-container-probing feature 
+
+. Apply the updated `KnativeServing` CR.
++
+[source,terminal]
+----
+$ oc apply -f <filename>
+----
+. Modify your multi-container service to include the specified probes.
++
+.Multi-container probing
+[source,yaml]
+----
+apiVersion: serving.knative.dev/v1
+kind: Service
+...
+spec:
+ template:
+   spec:
+     containers:
+       - name: first-container
+         image: ghcr.io/knative/helloworld-go:latest
+         ports:
+           - containerPort: 8080
+         readinessProbe: <1>
+           httpGet:
+             port: 8080
+       - name: second-container
+         image: gcr.io/knative-samples/helloworld-java
+         readinessProbe: <2>
+           httpGet:
+             port: 8090
+----
+<1> Readiness probe of the first container
+<2> Readiness probe of the second container
+
+== Additional resources
+* link:https://knative.dev/docs/serving/services/configure-probing/#general-understanding-of-knative-probing[General understanding of Knative Probing]
+