RHIDP-1595: How to use HA in RHDH (redhat-developer#967)

* Added content and rectified an error in another proc

* Added title

* Changing using to configuring

* Changing OCP to an attribute

* Fixing build error

* Alessandro's comment

* Fixed typos

* Fabrice's comments

* Incorporated Lindsey's comments

* Fabrice's comments

* Fixing yaml issue

* Minor change - Lindsey's comment

Author: pabel-rh

assemblies/assembly-configuring-high-availability.adoc

@@ -0,0 +1,14 @@
+:_mod-docs-content-type: ASSEMBLY
+:context: HighAvailability
+[id="{context}"]
+= Configuring high availability in {product}
+
+Previously, {product} supports a single-instance application. With this configuration, if the instance fails due to software crashes, hardware issues, or other unexpected disruptions, the entire {product} service becomes unavailable, preventing the development workflows or access to the resources. With high availability, you receive a failover mechanism that ensures the service is available even if one or more components fail. By increasing the number of replicas, you introduce redundancy to help increase higher productivity and minimize disruption.
+
+As an administrator, you can configure high availability in {product}. Once you set the high availability option in {product-short}, the {ocp-brand-name} built-in Load Balancer manages the ingress traffic and distributes the load to each pod. The {product-very-short} backend also manages concurrent requests or conflicts on the same resource. 
+
+You can configure high availability in {product-short} by scaling your `replicas` to a number greater than 1 in your configuration file. The configuration file that you use depends on the method that you used to install your {product-short} instance. If you used the Operator to install your {product-short} instance, configure the replica values in your `{product-custom-resource-type}` custom resource. If you used the Helm chart to install your {product-short} instance, configure the replica values in your Helm chart.
+
+include::modules/configuring-high-availability/proc-configuring-high-availability-in-rhdh-operator-deployment.adoc[leveloffset=+1]
+
+include::modules/configuring-high-availability/proc-configuring-high-availability-in-rhdh-helm-chart-deployment.adoc[leveloffset=+1]

assemblies/assembly-configuring-readonlyrootfilesystem.adoc

@@ -8,6 +8,6 @@ The {product} deployment consists of two containers: an `initContainer` that ins
 * The {product} Operator
 * The {product} Helm chart
 
- include::modules/configuring-readonlyrootfilesystem/proc-configuring-readonlyrootfilesystem-option-in-rhdh-operator-deployment.adoc[leveloffset=+1]
+include::modules/configuring-readonlyrootfilesystem/proc-configuring-readonlyrootfilesystem-option-in-rhdh-operator-deployment.adoc[leveloffset=+1]
 
- include::modules/configuring-readonlyrootfilesystem/proc-configuring-readonlyrootfilesystem-option-in-rhdh-helm-chart-deployment.adoc[leveloffset=+1]
+include::modules/configuring-readonlyrootfilesystem/proc-configuring-readonlyrootfilesystem-option-in-rhdh-helm-chart-deployment.adoc[leveloffset=+1]

modules/configuring-high-availability/proc-configuring-high-availability-in-rhdh-helm-chart-deployment.adoc

@@ -0,0 +1,19 @@
+[id="proc-configuring-high-availability-in-rhdh-helm-chart-deployment"]
+= Configuring high availability in a {product} Helm chart deployment
+
+When you are deploying {product-short} using the Helm chart, you must set `replicas` to a value greater than `1` in your Helm chart. The default value for `replicas` is `1`. 
+
+.Procedure
+To configure your {product-short} Helm chart for high availability, complete the following step:
+
+* In your Helm chart configuration file, set `replicas` to a value greater than `1`. For example:
++
+====
+[source,yaml,subs="+attributes,+quotes"]
+----
+upstream:
+  backstage:
+    replicas: _<replicas_value>_ <1>
+----
+====
+<1> Set the number of replicas based on the number of backup instances that you want to configure.

modules/configuring-high-availability/proc-configuring-high-availability-in-rhdh-operator-deployment.adoc

@@ -0,0 +1,25 @@
+[id="proc-configuring-high-availability-in-rhdh-operator-deployment"]
+= Configuring High availability in a {product} Operator deployment
+
+{product-very-short} instances that are deployed with the Operator use configurations in the `{product-custom-resource-type}` custom resource. In the `{product-custom-resource-type}` custom resource, the default value for the `replicas` field is `1`. If you want to configure your {product-very-short} instance for high availability, you must set `replicas` to a value greater than `1`.
+
+
+.Procedure
+
+* In your `{product-custom-resource-type}` custom resource, set `replicas` to a value greater than `1`. For example:
++
+====
+[source,yaml,subs="+attributes,+quotes"]
+----
+apiVersion: rhdh.redhat.com/v1alpha3 
+kind: Backstage 
+metadata: 
+  name: _<your_yaml_file>_ 
+spec:
+  application: 
+    ... 
+    replicas: _<replicas_value>_ <1>
+    ...
+----
+====
+<1> Set the number of replicas based on the number of backup instances that you want to configure.

modules/configuring-readonlyrootfilesystem/proc-configuring-readonlyrootfilesystem-option-in-rhdh-helm-chart-deployment.adoc

@@ -2,7 +2,7 @@
 = Configuring the readOnlyRootFilesystem option in a {product} Helm chart deployment
 
 .Procedure
-. In your 'values.yaml' file, add the `readOnlyRootFilesystem: true` line to the `containerSecurityContext` section. For example:
+. In your `values.yaml` file, add the `readOnlyRootFilesystem: true` line to the `containerSecurityContext` section. For example:
 +
 ====
 [source,yaml,subs="+attributes,+quotes"]

titles/configuring/master.adoc

@@ -21,6 +21,9 @@ include::modules/configuring-deployment/proc-configuring-deployment-by-using-the
 include::assemblies/assembly-configuring-readonlyrootfilesystem.adoc[leveloffset=+1]
 
 
+include::assemblies/assembly-configuring-high-availability.adoc[leveloffset=+1]
+
+
 include::assemblies/assembly-configuring-a-proxy.adoc[leveloffset=+1]