Merge branch 'andrey-cng-docs' into 'master'

Update main README for cng orchestrator

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/155681



Merged-by: Evan Read <eread@gitlab.com>
Approved-by: Evan Read <eread@gitlab.com>
Approved-by: Anastasia McDonald <amcdonald@gitlab.com>
Reviewed-by: Evan Read <eread@gitlab.com>
Reviewed-by: Andrejs Cunskis <acunskis@gitlab.com>
Co-authored-by: Andrejs Cunskis <acunskis@gitlab.com>

doc/development/testing_guide/end_to_end/test_pipelines.md

@@ -194,7 +194,12 @@ This stage is responsible for [allure test report](index.md#allure-report) gener
 The `e2e:test-on-cng` child pipeline runs tests against [Cloud Native GitLab](https://gitlab.com/gitlab-org/build/CNG) installation.
 Unlike `review-apps`, this pipeline uses local [kind](https://github.com/kubernetes-sigs/kind) Kubernetes cluster.
 
-Currently this pipeline is executed on nightly scheduled pipelines and is mainly responsible for testing compatibility with minimal supported version of `redis`.
+Deployment is managed by the [`cng`](../../../../gems/gitlab-cng/README.md) orchestrator tool, which you can also use to locally recreate CI/CD deployments.
+
+This pipeline is executed every two hours on scheduled pipelines and runs the following validations:
+
+- Main test suite against the `CNG` deployment using default chart configuration.
+- Minimal `health_check` test suite against the `CNG` deployment that uses minimal supported `redis` version.
 
 ### Setup
 
@@ -224,3 +229,11 @@ Jobs in `test` stage perform following actions:
 #### report
 
 This stage is responsible for [allure test report](index.md#allure-report) generation as well as test metrics upload.
+
+### Debugging
+
+To help with debugging:
+
+- Each test job prints a list of arguments that you can pass to the [`cng`](../../../../gems/gitlab-cng/README.md) orchestrator to exactly recreate
+  the same deployment for local debugging.
+- Cluster events log and all pod logs are saved in E2E test job artifacts.

gems/gitlab-cng/README.md

-# Cng
+# `cng`
 
-CLI tool to support setup and deployments of [Cloud Native GitLab](https://gitlab.com/gitlab-org/build/CNG) builds.
+`cng` is a CLI tool that supports setting up and deploying [Cloud Native GitLab](https://gitlab.com/gitlab-org/build/CNG) builds
+using the official [GitLab Chart](https://gitlab.com/gitlab-org/charts/gitlab).
+
+## Usage
+
+`cng` is internal gem so it is not published to [rubygems](https://rubygems.org/). Run `cng` by prefixing commands with
+`bundle exec` within its directory.
+
+```shell
+$ bundle exec cng
+Commands:
+  cng create [SUBCOMMAND]   # Manage deployment related object creation
+  cng destroy [SUBCOMMAND]  # Manage deployment related object cleanup
+  cng doctor                # Validate presence of all required system dependencies
+  cng help [COMMAND]        # Describe available commands or one specific command
+  cng log [SUBCOMMAND]      # Manage deployment related logs
+  cng version               # Print cng orchestrator version
+```
+
+## Add new deployments
+
+The main feature `cng` is to programmatically manage different deployment type configurations and setup. To implement new deployment configuration:
+
+1. Add a new subcommand method to the [`Deployment`](lib/gitlab/cng/commands/subcommands/deployment.rb) class. This allows you to to define your own input
+   arguments and documentation.
+1. Define a configuration class based on the [`Base`](lib/gitlab/cng/lib/deployment/configurations/_base.rb) configuration class. You can implement:
+   - `pre-deployment` setup: optional setup steps that are executed before installing the `GitLab` instance.
+   - `post-deployment` setup: optional setup steps that are executed after instance of `GitLab` has been installed.
+   - `helm` values: set of values to apply during installation.
+1. Define a cleanup class based on the [`Base`](lib/gitlab/cng/lib/deployment/configurations/cleanup/_base.rb) cleanup class. Implement a single method
+   that deletes all objects created by `pre-deployment` and `post-deployment` setup.
+
+## Tips
+
+### kubectl context
+
+`cng` CLI uses [`kubectl`](https://github.com/kubernetes/kubectl) and [Helm](https://github.com/helm/helm) to perform all `kubernetes`-related
+operations. When running a deployment, [current context](https://kubernetes.io/docs/reference/kubectl/generated/kubectl_config/kubectl_config_current-context/)
+is always used. If non-default arguments are used when running the deployment, make sure current context points to the cluster where the deployment should be executed.
+
+### Shell integration
+
+To make `cng` globally available in your shell without the need to run the commands from a specific folder and prefixed with `bundle exec`, add the following
+function to your shell's configuration file (for example,`.zshrc` or `.bash_profile`):
+
+```shell
+function cng() {
+  (cd $PATH_TO_GITLAB_REPO/gems/gitlab-cng && BUNDLE_AUTO_INSTALL=true bundle exec cng "$@")
+}
+```