[KOGITO-9940] Add documentation for Jobs Service support in the Opera…

…tor (#530)

serverlessworkflow/modules/ROOT/pages/cloud/index.adoc

@@ -29,6 +29,14 @@ xref:cloud/operator/install-serverless-operator.adoc[]
 Learn how to install the {operator_name} in a Kubernetes cluster
 --
 
+[.card]
+--
+[.card-title]
+xref:cloud/operator/enabling-jobs-service.adoc[]
+[.card-description]
+Learn how to deploy the Jobs Service using {operator_name} in a Kubernetes cluster
+--
+
 [.card]
 --
 [.card-title]

serverlessworkflow/modules/ROOT/pages/cloud/operator/enabling-jobs-service.adoc

@@ -0,0 +1,168 @@
+= Managing Jobs Service with the Operator
+:compat-mode!:
+// Metadata:
+:description: Configure Jobs Service using the `SonataFlowPlatform` CR.
+:keywords: sonataflow, serverless, operator, kubernetes, jobs service
+
+
+This document describes how to configure the Jobs Service instance using the SonataFlowPlarform CR.
+
+== Automate the Jobs Service instance management with the `SonataFlow` Operator
+
+It is possible to deploy the Jobs Service manually, leveraging the Operator offers a more seamless integration by
+combining it with namespace configuration through the SonataFlowPlatform Custom Resource (CR). When the Operator oversees
+the lifecycle of the jobs service, it automatically injects necessary properties during creation into the SonataFlow workflows.
+This integration eliminates the need for including these properties within the SonataFlow workflow CR instance, simplifying workflow management.
+== Configuring Jobs Service in the SonataFlowPlatform CR
+
+To enable the deployment of a Jobs Service instance, the `SonataFlowPlatform` CRD exposes a set of fields that allow the user to 
+configure the running instance. 
+
+=== Ephemeral persistence
+The basic runtime is to deploy the Jobs Service with an ephemeral backend running in the same container
+as the Jobs Service runtime.
+
+[source,yaml,subs="attributes+"]
+---
+apiVersion: sonataflow.org/v1alpha08
+kind: SonataFlowPlatform
+metadata:
+  name: sonataflow-platform
+spec:
+  services:
+    jobService: {}
+---
+
+When executing this manifest, the operator will reconcile generating a pod hosting the Jobs Service:
+
+[source,shell,subs="attributes+"]
+---
+$>kubectl get pod -n sonataflow
+NAME                                               READY   STATUS    RESTARTS   AGE
+sonataflow-platform-jobs-service-cdf85d969-sbwkj   1/1     Running   0          108s
+---
+
+Keep in mind that this setup is not recommended for production environments, especially because the data does not persist when the pod restarts.
+
+=== Using an existing PostgreSQL service
+For robust environments it is recommened to use an dedicated database service and configure Jobs Service to make use of it. Currently, the Jobs Service
+only supports PostgreSQL database.
+
+Configuring Jobs Service to communicate with an existing PostgreSQL instance is supported in two ways. In both cases it requires providing the persistence
+configuration, one by using the Jobs Service's persistence field and the other one using the persistence field defined in the `SonataFlowPlatform` CR
+deployed in the same namespace.
+
+By default, the persistence specification defined in the `SonataFlow` workflow's CR takes priority over the one in the `SonataFlowPlatform` persistence specification.
+
+==== Using the persistence field defined in the `SonataFlowPlatform` CR
+Using the persistence configuration in the `SonataFlowPlatform` CR located in the same namespace requires to have the `SonataFlow` CR persistence field configured
+to have an empty `{}` value, signaling the Operator to derive the persistence from the active `SonataFlowPlatform`, when available. If no persistence is defined
+the operator will fallback to the ephemeral persistence previously described.
+
+[source,yaml,subs="attributes+"]
+---
+apiVersion: sonataflow.org/v1alpha08
+kind: SonataFlowPlatform
+metadata:
+  name: sonataflow-platform
+spec:
+  persistence:
+    postgresql:
+      secretRef:
+        name: postgres-secrets
+        userKey: POSTGRES_USER
+        passwordKey: POSTGRES_PASSWORD
+      serviceRef:
+        name: postgres
+        port: 5432
+        databaseName: sonataflow
+---
+
+And the `SonataFlow` CR looks like this:
+
+[source,yaml,subs="attributes+"]
+---
+apiVersion: sonataflow.org/v1alpha08
+kind: SonataFlow
+metadata:
+  name: callbackstatetimeouts
+  annotations:
+    sonataflow.org/description: Callback State Timeouts Example k8s
+    sonataflow.org/version: 0.0.1
+spec:
+  persistence: {}
+...
+---
+
+When using the `jdbcUrl` field instead of `serviceRef`, the user is responsible for providing the correct JDBC URL connection value that does not contain a `database schema`
+because the operator will use verbatim the contents of this field as the JDBC connection in the Jobs Service pod, and if it provides a schema that has been used or formatted 
+by a different client, the pod will fail to run.
+
+===== Using the persistence field inside the service specification
+You can specify define the persistence configuration directly in the Jobs Service specification. The structure is the same as in the `SonataFlowPlatform` CR and also
+consist on the credentials to access the PostgreSQL instance, and the kubernetes service reference to generate the connectivity.
+
+[source,yaml,subs="attributes+"]
+---
+apiVersion: sonataflow.org/v1alpha08
+kind: SonataFlowPlatform
+metadata:
+  name: callbackstatetimeouts
+spec:
+  persistence:
+    postgresql:
+      secretRef:
+        name: postgres-secrets
+        userKey: POSTGRES_USER
+        passwordKey: POSTGRES_PASSWORD
+      serviceRef:
+        name: postgres
+        port: 5432
+        databaseName: sonataflow
+        databaseSchema: jobs-service
+---
+
+In this example we're using a PostgreSQL service located in the same namespace where the Jobs Service is deployed, pointing to the default PostgreSQL port of 5432
+and referencing the database `sonataflow` and schema `jobs-service`. By default, when the Jobs Service pod starts it will recreate the schema in the given location
+if it doesn't exist.
+
+The values of `POSTGRES_USER` and `POSTGRES_PASSWORD` point to the keys in the secret that contains the PostgreSQL credentials.
+
+[source,shell,subs="attributes+"]
+---
+$>kubectl describe secrets postgres-secrets
+Name:         postgres-secrets
+Namespace:    default
+Labels:       <none>
+Annotations:  <none>
+
+Type:  Opaque
+
+Data
+\\\\====
+PGDATA:             28 bytes
+POSTGRES_DATABASE:  10 bytes
+POSTGRES_PASSWORD:  10 bytes
+POSTGRES_USER:      10 bytes
+---
+
+Putting everything together will render an output similar to this one below:
+
+[source,shell,subs="attributes+"]
+---
+$>kubectl get pod -w -n sonataflow
+NAME                                                READY   STATUS    RESTARTS   AGE
+postgres-64c9ddb6bc-v96qb                           1/1     Running   0          14m
+sonataflow-platform-jobs-service-79bb6bc67f-gvcg4   1/1     Running   0           1m
+---
+
+== Conclusion
+The Operator extends its scope to manage the lifecycle of the Jobs Service instance, thus removing the burden on the users and allowing them to focus on the
+implementation of the `Sonataworkflows. It takes care of managing the Jobs Service deployment, dynamically configures its application properties
+when the Data Index service is also available and managed by the Operator, and finally inject application properties in `SonataFlow` workflows in the target
+namespace when the Jobs Service is available.
+
+== Additional resources
+* xref:cloud/operator/install-serverless-operator.adoc[]
+
+include::../../../pages/_common-content/report-issue.adoc[]

serverlessworkflow/modules/ROOT/pages/cloud/operator/install-serverless-operator.adoc

@@ -164,5 +164,6 @@ The URL should be the same used when installing the operator.
 
 * xref:cloud/operator/known-issues.adoc[]
 * xref:cloud/operator/developing-workflows.adoc[]
+* xref:cloud/operator/enabling-jobs-service.adoc[]
 
 include::../../../pages/_common-content/report-issue.adoc[]