Merge branch 'docs/refactor-k8s-cluster' into 'master'

Improve Clusters documentation

See merge request gitlab-org/gitlab-ce!16435

2 files changed, 241 insertions, 45 deletions

diff --git a/doc/user/project/clusters/index.md b/doc/user/project/clusters/index.md
index 130f7897b1a..e87b4403854 100644
--- a/doc/user/project/clusters/index.md
+++ b/doc/user/project/clusters/index.md
@@ -1,26 +1,28 @@
 # Connecting GitLab with a Kubernetes cluster
 
-> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/35954) in 10.1.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/35954) in GitLab 10.1.
+
+Connect your project to Google Kubernetes Engine (GKE) or an existing Kubernetes
+cluster in a few steps.
 
 With a cluster associated to your project, you can use Review Apps, deploy your
 applications, run your pipelines, and much more, in an easy way.
 
-Connect your project to Google Kubernetes Engine (GKE) or your own Kubernetes
-cluster in a few steps.
-
-NOTE: **Note:**
-The Cluster integration will eventually supersede the
-[Kubernetes integration](../integrations/kubernetes.md). For the moment,
-you can create only one cluster.
+There are two options when adding a new cluster to your project; either associate
+your account with Google Kubernetes Engine (GKE) so that you can [create new
+clusters](#adding-and-creating-a-new-gke-cluster-via-gitlab) from within GitLab,
+or provide the credentials to an [existing Kubernetes cluster](#adding-an-existing-kubernetes-cluster).
 
 ## Prerequisites
 
-In order to be able to manage your GKE cluster through GitLab, the following
-prerequisites must be met:
+In order to be able to manage your Kubernetes cluster through GitLab, the
+following prerequisites must be met.
+
+**For a cluster hosted on GKE:**
 
 - The [Google authentication integration](../../../integration/google.md) must
   be enabled in GitLab at the instance level. If that's not the case, ask your
-  administrator to enable it.
+  GitLab administrator to enable it.
 - Your associated Google account must have the right privileges to manage
   clusters on GKE. That would mean that a [billing
   account](https://cloud.google.com/billing/docs/how-to/manage-billing-account)
@@ -31,41 +33,88 @@ prerequisites must be met:
 - You must have [Resource Manager
   API](https://cloud.google.com/resource-manager/)
 
-If all of the above requirements are met, you can proceed to add a new GKE
+**For an existing Kubernetes cluster:**
+
+- Since the cluster is already created, there are no prerequisites.
+
+---
+
+If all of the above requirements are met, you can proceed to add a new Kubernetes
 cluster.
 
-## Adding a cluster
+## Adding and creating a new GKE cluster via GitLab
+
+NOTE: **Note:**
+You need Master [permissions] and above to access the Clusters page.
+
+Before proceeding, make sure all [prerequisites](#prerequisites) are met.
+To add a new cluster hosted on GKE to your project:
+
+1. Navigate to your project's **CI/CD > Clusters** page.
+1. Click on **Add cluster**.
+1. Click on **Create with GKE**.
+1. Connect your Google account if you haven't done already by clicking the
+   **Sign in with Google** button.
+1. Fill in the requested values:
+  - **Cluster name** (required) - The name you wish to give the cluster.
+  - **GCP project ID** (required) - The ID of the project you created in your GCP
+    console that will host the Kubernetes cluster. This must **not** be confused
+    with the project name. Learn more about [Google Cloud Platform projects](https://cloud.google.com/resource-manager/docs/creating-managing-projects).
+  - **Zone** - The [zone](https://cloud.google.com/compute/docs/regions-zones/)
+    under which the cluster will be created.
+  - **Number of nodes** - The number of nodes you wish the cluster to have.
+  - **Machine type** - The [machine type](https://cloud.google.com/compute/docs/machine-types)
+    of the Virtual Machine instance that the cluster will be based on.
+  - **Environment scope** - The [associated environment](#setting-the-environment-scope) to this cluster.
+1. Finally, click the **Create cluster** button.
+
+After a few moments, your cluster should be created. If something goes wrong,
+you will be notified.
+
+You can now proceed to install some pre-defined applications and then
+enable the Cluster integration.
+
+## Adding an existing Kubernetes cluster
 
 NOTE: **Note:**
-You need Master [permissions] and above to add a cluster.
-
-There are two options when adding a new cluster; either use Google Kubernetes
-Engine (GKE) or provide the credentials to your own Kubernetes cluster.
-
-To add a new cluster:
-
-1. Navigate to your project's **CI/CD > Cluster** page
-1. If you want to let GitLab create a cluster on GKE for you, go through the
-   following steps, otherwise skip to the next one.
-    1. Click on **Create with GKE**
-    1. Connect your Google account if you haven't done already by clicking the
-       **Sign in with Google** button
-    1. Fill in the requested values:
-      - **Cluster name** (required) - The name you wish to give the cluster.
-      - **GCP project ID** (required) - The ID of the project you created in your GCP
-        console that will host the Kubernetes cluster. This must **not** be confused
-        with the project name. Learn more about [Google Cloud Platform projects](https://cloud.google.com/resource-manager/docs/creating-managing-projects).
-      - **Zone** - The [zone](https://cloud.google.com/compute/docs/regions-zones/)
-        under which the cluster will be created.
-      - **Number of nodes** - The number of nodes you wish the cluster to have.
-      - **Machine type** - The [machine type](https://cloud.google.com/compute/docs/machine-types)
-        of the Virtual Machine instance that the cluster will be based on.
-      - **Project namespace** - The unique namespace for this project. By default you
-        don't have to fill it in; by leaving it blank, GitLab will create one for you.
-1. If you want to use your own existing Kubernetes cluster, click on
-   **Add an existing cluster** and fill in the details as described in the
-   [Kubernetes integration](../integrations/kubernetes.md) documentation.
-1. Finally, click the **Create cluster** button
+You need Master [permissions] and above to access the Clusters page.
+
+To add an existing Kubernetes cluster to your project:
+
+1. Navigate to your project's **CI/CD > Clusters** page.
+1. Click on **Add cluster**.
+1. Click on **Add an existing cluster** and fill in the details:
+    - **Cluster name** (required) - The name you wish to give the cluster.
+    - **Environment scope** (required)- The
+      [associated environment](#setting-the-environment-scope) to this cluster.
+    - **API URL** (required) -
+      It's the URL that GitLab uses to access the Kubernetes API. Kubernetes
+      exposes several APIs, we want the "base" URL that is common to all of them,
+      e.g., `https://kubernetes.example.com` rather than `https://kubernetes.example.com/api/v1`.
+    - **CA certificate** (optional) -
+      If the API is using a self-signed TLS certificate, you'll also need to include
+      the `ca.crt` contents here.
+    - **Token** -
+      GitLab authenticates against Kubernetes using service tokens, which are
+      scoped to a particular `namespace`. If you don't have a service token yet,
+      you can follow the
+      [Kubernetes documentation](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/)
+      to create one. You can also view or create service tokens in the
+      [Kubernetes dashboard](https://kubernetes.io/docs/tasks/access-application-cluster/web-ui-dashboard/#config)
+      (under **Config > Secrets**).
+    - **Project namespace** (optional) - The following apply:
+      - By default you don't have to fill it in; by leaving it blank, GitLab will
+        create one for you.
+      - Each project should have a unique namespace.
+      - The project namespace is not necessarily the namespace of the secret, if
+        you're using a secret with broader permissions, like the secret from `default`.
+      - You should **not** use `default` as the project namespace.
+      - If you or someone created a secret specifically for the project, usually
+        with limited permissions, the secret's namespace and project namespace may
+        be the same.
+1. Finally, click the **Create cluster** button.
+
+The Kubernetes service takes the following parameters:
 
 After a few moments, your cluster should be created. If something goes wrong,
 you will be notified.
@@ -85,6 +134,91 @@ added directly to your configured cluster. Those applications are needed for
 | [Ingress](https://kubernetes.io/docs/concepts/services-networking/ingress/) | 10.2+ | Ingress can provide load balancing, SSL termination, and name-based virtual hosting. It acts as a web proxy for your applications and is useful if you want to use [Auto DevOps](../../../topics/autodevops/index.md) or deploy your own web apps. |
 | [Prometheus](https://prometheus.io/docs/introduction/overview/) | 10.4+ | Prometheus is an open-source monitoring and alerting system useful to supervise your deployed applications |
 
+## Setting the environment scope
+
+When adding more than one clusters, you need to differentiate them with an
+environment scope. The environment scope associates clusters and
+[environments](../../../ci/environments.md) in an 1:1 relationship similar to how the
+[environment-specific variables](../../../ci/variables/README.md#limiting-environment-scopes-of-secret-variables)
+work.
+
+The default environment scope is `*`, which means all jobs, regardless of their
+environment, will use that cluster. Each scope can only be used by a single
+cluster in a project, and a validation error will occur if otherwise.
+
+---
+
+For example, let's say the following clusters exist in a project:
+
+| Cluster    | Environment scope   |
+| ---------- | ------------------- |
+| Development| `*`                 |
+| Staging    | `staging/*`         |
+| Production | `production/*`      |
+
+And the following environments are set in [`.gitlab-ci.yml`](../../../ci/yaml/README.md):
+
+```yaml
+stages:
+- test
+- deploy
+
+test:
+  stage: test
+  script: sh test
+
+deploy to staging:
+  stage: deploy
+  script: make deploy
+  environment:
+    name: staging/$CI_COMMIT_REF_NAME
+    url: https://staging.example.com/
+
+deploy to production:
+  stage: deploy
+  script: make deploy
+  environment:
+    name: production/$CI_COMMIT_REF_NAME
+    url: https://example.com/
+```
+
+The result will then be:
+
+- The development cluster will be used for the "test" job.
+- The staging cluster will be used for the "deploy to staging" job.
+- The production cluster will be used for the "deploy to production" job.
+
+## Multiple Kubernetes clusters
+
+> Introduced in [GitLab Enterprise Edition Premium][ee] 10.3.
+
+With GitLab EEP, you can associate more than one Kubernetes clusters to your
+project. That way you can have different clusters for different environments,
+like dev, staging, production, etc.
+
+To add another cluster, follow the same steps as described in [adding a
+Kubernetes cluster](#adding-a-kubernetes-cluster) and make sure to
+[set an environment scope](#setting-the-environment-scope) that will
+differentiate the new cluster with the rest.
+
+## Deployment variables
+
+The Kubernetes cluster integration exposes the following
+[deployment variables](../../../ci/variables/README.md#deployment-variables) in the
+GitLab CI/CD build environment:
+
+- `KUBE_URL` - Equal to the API URL.
+- `KUBE_TOKEN` - The Kubernetes token.
+- `KUBE_NAMESPACE` - The Kubernetes namespace is auto-generated if not specified.
+  The default value is `<project_name>-<project_id>`. You can overwrite it to
+  use different one if needed, otherwise the `KUBE_NAMESPACE` variable will
+  receive the default value.
+- `KUBE_CA_PEM_FILE` - Only present if a custom CA bundle was specified. Path
+  to a file containing PEM data.
+- `KUBE_CA_PEM` (deprecated) - Only if a custom CA bundle was specified. Raw PEM data.
+- `KUBECONFIG` - Path to a file containing `kubeconfig` for this deployment.
+  CA bundle would be embedded if specified.
+
 ## Enabling or disabling the Cluster integration
 
 After you have successfully added your cluster information, you can enable the
@@ -111,4 +245,62 @@ To remove the Cluster integration from your project, simply click on the
 **Remove integration** button. You will then be able to follow the procedure
 and [add a cluster](#adding-a-cluster) again.
 
+## What you can get with the Kubernetes integration
+
+Here's what you can do with GitLab if you enable the Kubernetes integration.
+
+### Deploy Boards (EEP)
+
+> Available in [GitLab Enterprise Edition Premium][ee].
+
+GitLab's Deploy Boards offer a consolidated view of the current health and
+status of each CI [environment](../../../ci/environments.md) running on Kubernetes,
+displaying the status of the pods in the deployment. Developers and other
+teammates can view the progress and status of a rollout, pod by pod, in the
+workflow they already use without any need to access Kubernetes.
+
+[> Read more about Deploy Boards](https://docs.gitlab.com/ee/user/project/deploy_boards.html)
+
+### Canary Deployments (EEP)
+
+> Available in [GitLab Enterprise Edition Premium][ee].
+
+Leverage [Kubernetes' Canary deployments](https://kubernetes.io/docs/concepts/cluster-administration/manage-deployment/#canary-deployments)
+and visualize your canary deployments right inside the Deploy Board, without
+the need to leave GitLab.
+
+[> Read more about Canary Deployments](https://docs.gitlab.com/ee/user/project/canary_deployments.html)
+
+### Kubernetes monitoring
+
+Automatically detect and monitor Kubernetes metrics. Automatic monitoring of
+[NGINX ingress](../integrations/prometheus_library/nginx.md) is also supported.
+
+[> Read more about Kubernetes monitoring](../integrations/prometheus_library/kubernetes.md)
+
+### Auto DevOps
+
+Auto DevOps automatically detects, builds, tests, deploys, and monitors your
+applications.
+
+To make full use of Auto DevOps(Auto Deploy, Auto Review Apps, and Auto Monitoring)
+you will need the Kubernetes project integration enabled.
+
+[> Read more about Auto DevOps](../../../topics/autodevops/index.md)
+
+### Web terminals
+
+NOTE: **Note:**
+Introduced in GitLab 8.15. You must be the project owner or have `master` permissions
+to use terminals. Support is limited to the first container in the
+first pod of your environment.
+
+When enabled, the Kubernetes service adds [web terminal](../../../ci/environments.md#web-terminals)
+support to your [environments](../../../ci/environments.md). This is based on the `exec` functionality found in
+Docker and Kubernetes, so you get a new shell session within your existing
+containers. To use this integration, you should deploy to Kubernetes using
+the deployment variables above, ensuring any pods you create are labelled with
+`app=$CI_ENVIRONMENT_SLUG`. GitLab will do the rest!
+
 [permissions]: ../../permissions.md
+[ee]: https://about.gitlab.com/gitlab-ee/
diff --git a/doc/user/project/integrations/kubernetes.md b/doc/user/project/integrations/kubernetes.md
index 710cf78e84f..543baaa81e1 100644
--- a/doc/user/project/integrations/kubernetes.md
+++ b/doc/user/project/integrations/kubernetes.md
@@ -2,11 +2,15 @@
 last_updated: 2017-12-28
 ---
 
-CAUTION: **Warning:**
-Kubernetes service integration has been deprecated in GitLab 10.3. If the service is active the cluster information still be editable, however we advised to disable and reconfigure the clusters using the new [Clusters](../clusters/index.md) page. If the service is inactive the fields will be uneditable. Read [GitLab 10.3 release post](https://about.gitlab.com/2017/12/22/gitlab-10-3-released/#kubernetes-integration-service) for more information.
-
 # GitLab Kubernetes / OpenShift integration
 
+CAUTION: **Warning:**
+The Kubernetes service integration has been deprecated in GitLab 10.3. If the
+service is active, the cluster information will still be editable, however we
+advise to disable and reconfigure the clusters using the new
+[Clusters](../clusters/index.md) page. If the service is inactive, the fields
+will not be editable. Read [GitLab 10.3 release post](https://about.gitlab.com/2017/12/22/gitlab-10-3-released/#kubernetes-integration-service) for more information.
+
 GitLab can be configured to interact with Kubernetes, or other systems using the
 Kubernetes API (such as OpenShift).