Improve documentations for Helm and FluxCD

In the current Helm documentation more details were added,
showing how to deploy an application using Helm.

Created a documentation to FluxCD showing how to deploy
an application using FluxCD resources.

Created a link in usertasks index to the new FluxCD documentation.

Fix merge conflict
Fix editorial issues

Closes-bug: 2068023

Change-Id: I20307dc98da4a9872ba441200499d4b3173d5f10

doc/source/usertasks/kubernetes/index-usertasks-kub-1291759aa985.rst

@@ -57,6 +57,7 @@ Application management
    :maxdepth: 1
 
    kubernetes-user-tutorials-helm-package-manager
+   kubernetes-user-tutorials-fluxcd-deploy-00d5706c3358
 
 ---------------------
 Local Docker registry

doc/source/usertasks/kubernetes/kubernetes-user-tutorials-fluxcd-deploy-00d5706c3358.rst

@@ -0,0 +1,132 @@
+.. _kubernetes-user-tutorials-fluxcd-deploy-00d5706c3358:
+
+=================
+Deploy via FluxCD
+=================
+
+`FluxCD <https://fluxcd.io/>`__ is a continuous delivery tool for Kubernetes.
+It is used to keep Kubernetes in sync with configuration sources such as Git
+repositories.
+
+|prod-long| does not have FluxCD CLI, but it does have `FluxCD resources
+<https://fluxcd.io/flux/components/>`__ which can be used to deploy
+applications.
+
+Using FluxCD resources you can deploy your applications and apply GitOps to
+them.
+
+Create a Source Controller
+**************************
+
+The Source Controller is a FluxCD resource that serves as the pivotal point
+for acquiring artifacts necessary for deployment. It is crucial for ensuring
+easy access to important elements such as source code, configuration files,
+and other essential components for deploying your application. Essentially, it
+acts as the gateway facilitating the acquisition process, guaranteeing that
+your application has the requisite resources for deployment.
+
+There are five types of `Source Controllers
+<https://fluxcd.io/flux/components/source/api/v1beta2/>`__, in this example
+GitRepository will be used. The GitRepository is a type of Source Controller
+that is used to manage applications defined within Git repositories.
+
+In the active controller, run:
+
+.. code-block:: none
+
+    cat <<EOF > gitrepository.yaml
+    apiVersion: source.toolkit.fluxcd.io/v1
+    kind: GitRepository
+    metadata:
+      name: <source-controller-name>
+    spec:
+      interval: 5m
+      url: <git-repository-url>
+      ref:
+        branch: <branch>
+
+    EOF
+
+.. code-block:: shell
+
+    $ kubectl apply -f gitrepository.yaml
+
+
+The above command creates a GitRepository resource, you can check by running:
+
+.. code-block:: shell
+
+    $ kubectl get gitrepositories
+
+
+Create a Helm Controller
+************************
+
+For deploying applications via FluxCD, create a `Helm Controller
+<https://fluxcd.io/flux/components/helm/>`__ or `Kustomize Controller
+<https://fluxcd.io/flux/components/kustomize/>`__, each one has its
+specifications.
+
+For deploying via Helm, create a HelmRelease resource.
+
+.. code-block:: none
+
+    cat <<EOF > helmrelease.yaml
+    apiVersion: "helm.toolkit.fluxcd.io/v2beta1"
+    kind: HelmRelease
+    metadata:
+      name: <helm-release-name>
+    spec:
+      releaseName: <helm-release-name>
+      interval: 5m
+      chart:
+        spec:
+          chart: <helm-chart-path> # Relative path of the Helm chart inside the repo.
+          version: <helm-chart-version>
+          sourceRef:
+            kind: GitRepository
+            name: <source-controller-name>
+        values: # Override values for the Helm chart.
+          foo:
+            bar: value
+
+    EOF
+
+.. code-block:: shell
+
+    $ kubectl apply -f helmrelease.yaml
+
+This command creates a HelmChart and a HelmRelease resources, the HelmChart
+stores the Helm chart loaded from the GitRepository, and the HelmRelease is
+responsible for applying Helm actions, such as configuring, installing or
+upgrading the Helm Chart.
+
+You can check if the resources were created by running:
+
+.. code-block:: shell
+
+    $ kubectl get helmcharts
+
+.. code-block:: shell
+
+    $ kubectl get helmreleases
+
+To check the application deployment:
+
+.. code-block:: shell
+
+    $ kubectl get all
+
+-----------------------------
+Modify the Application Values
+-----------------------------
+
+To modify values of your HelmRelease, you can edit the ``spec.values`` section
+of ``helmrelease.yaml`` file and apply it again:
+
+.. code-block:: shell
+
+    $ kubectl apply -f helmrelease.yaml
+
+This will cause the controller to perform Helm actions on the deployment.
+

doc/source/usertasks/kubernetes/kubernetes-user-tutorials-helm-package-manager.rst

@@ -11,18 +11,79 @@ be used to securely manage the lifecycle of applications within the Kubernetes c
 
 .. rubric:: |context|
 
-Helm packages are defined by Helm charts with container information sufficient
+Helm packages are defined by Helm charts which contain all of the Kubernetes
-for managing a Kubernetes application. You can configure, install, and upgrade
+resource definitions necessary to run an application inside of a Kubernetes
-your Kubernetes applications using Helm charts. Helm charts are defined with a
+cluster. In |prod|, you can configure, install, and upgrade your Kubernetes
-default set of values that describe the behavior of the service installed
+applications using Helm charts.
-within the Kubernetes cluster.
 
-|prod| recommends a non-admin end-user to install a Helm v3 client on a remote
+The Helm v3 client can be installed on a remote workstation and used to
-workstation to enable management of their Kubernetes applications.
+remotely manage your Kubernetes application on |prod|, see :ref:`Security -
+Access the System <index-security-kub-81153c1254c3>` and :ref:`Remote CLI
+access <index-usertasks-kub-1291759aa985>`.
 
 For more information on Helm, see the documentation at `https://helm.sh/docs/
 <https://helm.sh/docs/>`__.
 
-For more information on how to configure and use Helm both locally and remotely, see :ref:`Configure Local CLI Access <configure-local-cli-access>`,
+For more information on how to configure and use Helm both locally and
+remotely, see :ref:`Configure Local CLI Access <configure-local-cli-access>`,
 and :ref:`Configure Remote CLI Access <configure-remote-cli-access>`.
 
+---------------
+Deploy via Helm
+---------------
+
+*********************
+Use Helm Package File
+*********************
+
+You can use the packaged Helm chart from your development environment, and use
+the `Helm CLI <https://helm.sh/docs/intro/install/>`__ to install the package.
+
+#.  Install your Helm package on |prod|
+
+    The command below, executed remotely or locally, will deploy the
+    application to the StarlingX-managed Kubernetes cluster:
+
+    .. code-block:: shell
+
+        $ helm install [ -f <myvalues.yaml-file> | --set <attribute-name>=<attribute-value> ] <appName> <package>.tgz
+
+    where:
+
+    The helm chart/application will be deployed with a default set of values;
+    unless those values are overridden with ``-f`` and/or ``--set`` options.
+
+*******************
+Use Helm Repository
+*******************
+
+Helm charts are defined with a default set of values that describe the behavior
+of the service installed within the Kubernetes cluster.
+
+You can install the helm application from a Helm charts repository
+``<https://helm.sh/docs/helm/helm_repo/>``.
+
+#.  Add the URL for the Helm chart repository (containing the helm chart you
+    want to install) to the list of Helm chart repositories configured for your
+    helm client.
+
+    .. code-block:: shell
+
+        $ helm repo add <name> <helm-charts-repo-url>
+
+    .. code-block:: shell
+
+        $ helm repo update
+
+#.  Install the Helm application with the following command which will search
+    for the specified Helm chart in the configured Helm chart repositories, and
+    install it.
+
+    .. code-block:: shell
+
+        $ helm install [ -f <myvalues.yaml-file> | --set <attribute-name>=<attribute-value> ] <appName> <name>/<chart-name>
+
+    where:
+
+    The helm chart/application will be deployed with a default set of values;
+    unless those values are overridden with ``-f`` and/or ``--set`` options.