Add instruction in how to install Knative with Knative operators (#2261)

docs/install/README.md

@@ -1,4 +1,5 @@
 
-To install Knative components on your Kubernetes cluster, follow our [installation guide](./any-kubernetes-cluster.md).
+To install Knative components on your Kubernetes cluster, follow the [installation guide](./any-kubernetes-cluster.md) or
+[installation guide with Knative Operators](./knative-with-operators.md).
 
-To install the Knative CLI, follow our [installation guide](./install-kn.md).
+To install the Knative CLI, follow the [installation guide](./install-kn.md).

docs/install/knative-with-operators.md

@@ -0,0 +1,256 @@
+---
+title: "Installing Knative components using Operators"
+weight: 10
+type: "docs"
+---
+
+Knative provides operators as tools to install, configure and manage Knative. This guide explains how to install and
+uninstall Knative using Knative operators.
+
+Each component in Knative has a separate operator for installation and configuration. This means that there is a [Serving operator](https://github.com/knative/serving-operator)
+and an [Eventing operator](https://github.com/knative/eventing-operator), and you can choose to install one or both independently.
+
+## Before you begin
+
+Knative installation using Operators requires the following:
+
+- A Kubernetes cluster v1.15 or newer, as well as a compatible kubectl. This guide assumes that you've already created
+a Kubernetes cluster. If you have only one node for your cluster, set CPUs to at least 6, Memory to at least 6.0 GB,
+Disk storage to at least 30 GB. If you have multiple nodes for your cluster, set CPUs to at least 2, Memory to at least
+4.0 GB, Disk storage to at least 20 GB for each node.
+- The Kubernetes cluster must be able to access the internet, since Knative operators download images online.
+- Istio:
+    - [Download and install Istio](https://knative.dev/development/install/installing-istio/#downloading-istio-and-installing-crds). Go through all the 4 sub-steps.
+    - [Update your Istio to use cluster local gateway](https://knative.dev/development/install/installing-istio/#updating-your-install-to-use-cluster-local-gateway).
+
+## Limitations of Knative Operators:
+
+Knative Operators use custom resources (CRs) to configure your Knative deployment.
+
+ - Currently, the CRs included with Knative Operators do not provide high availability (HA) capabilities.
+ - Knative Operators have not been tested in a production environment, and should be used for development or test purposes only.
+
+## Install Knative Serving with Operator:
+
+Information about Knative Serving Operator releases can be found on the [Releases page](https://github.com/knative/serving-operator/releases).
+
+### Installing the Knative Serving Operator
+
+__From releases__:
+
+Run the following command to install Knative Serving Operator:
+
+```
+kubectl apply -f https://github.com/knative/serving-operator/releases/download/v0.13.0/serving-operator.yaml
+```
+
+__From source code__:
+
+You can also install Knative Operators from source using `ko`.
+
+1. Install the [ko](https://github.com/google/ko) build tool.
+1. Install the operator in the root directory of the source using the following command:
+
+```
+ko apply -f config/
+```
+
+### Verify the operator installation
+
+Verify the installation of Knative Serving Operator using the command:
+
+```
+kubectl get deployment knative-serving-operator
+```
+
+If the operator is installed correctly, the deployment should show a `Ready` status. Here is a sample output:
+
+```
+NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
+knative-serving-operator   1/1     1            1           19h
+```
+
+### Track the log
+
+Use the following command to track the log of the operator:
+
+```
+kubectl logs -f $(kubectl get pods -l name=knative-serving-operator -o name)
+```
+
+### Installing the Knative Serving component
+
+1. Create and apply the Knative Serving CR:
+
+```
+cat <<-EOF | kubectl apply -f -
+apiVersion: v1
+kind: Namespace
+metadata:
+ name: knative-serving
+---
+apiVersion: operator.knative.dev/v1alpha1
+kind: KnativeServing
+metadata:
+  name: knative-serving
+  namespace: knative-serving
+EOF
+```
+
+2. Verify the Knative Serving deployment:
+
+```
+kubectl get deployment -n knative-serving
+```
+
+If Knative Serving has been successfully deployed, all deployments of the Knative Serving will show `READY` status. Here
+is a sample output:
+
+```
+NAME               READY   UP-TO-DATE   AVAILABLE   AGE
+activator          1/1     1            1           19h
+autoscaler         1/1     1            1           19h
+autoscaler-hpa     1/1     1            1           19h
+controller         1/1     1            1           19h
+networking-istio   1/1     1            1           19h
+webhook            1/1     1            1           19h
+```
+
+## Install Knative Eventing with Operator:
+
+Information about Knative Eventing Operator releases can be found on the [Releases page](https://github.com/knative/eventing-operator/releases).
+
+### Installing the Knative Eventing Operator
+
+__From releases__:
+
+Run the following command to install Knative Eventing Operator:
+
+```
+kubectl apply -f https://github.com/knative/eventing-operator/releases/download/v0.13.0/eventing-operator.yaml
+```
+
+__From source code__:
+
+You can also install Knative Operators from source using `ko`.
+
+- Install the [ko]((https://github.com/google/ko)) build tool.
+- Install the operator in the root directory of the source using the following command:
+
+```
+ko apply -f config/
+```
+
+### Verify the operator installation
+
+Verify the installation of Knative Eventing Operator using the command:
+
+```
+kubectl get deployment knative-eventing-operator
+```
+
+If the operator is installed correctly, the deployment should show a `Ready` status. Here is a sample output:
+
+```
+NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
+knative-eventing-operator   1/1     1            1           19h
+```
+
+### Track the log
+
+Use the following command to track the log of the operator:
+
+```
+kubectl logs -f $(kubectl get pods -l name=knative-eventing-operator -o name)
+```
+
+### Installing the Knative Eventing component
+
+1. Create and apply the Knative eventing CR:
+
+```
+cat <<-EOF | kubectl apply -f -
+apiVersion: v1
+kind: Namespace
+metadata:
+ name: knative-eventing
+---
+apiVersion: operator.knative.dev/v1alpha1
+kind: KnativeEventing
+metadata:
+  name: knative-eventing
+  namespace: knative-eventing
+EOF
+```
+
+2. Verify the Knative Eventing deployment:
+
+```
+kubectl get deployment -n knative-eventing
+```
+
+If Knative Eventing has been successfully deployed, all deployments of the Knative Eventing will show `READY` status. Here
+is a sample output:
+
+```
+NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
+broker-controller     1/1     1            1           42h
+eventing-controller   1/1     1            1           42h
+eventing-webhook      1/1     1            1           42h
+imc-controller        1/1     1            1           42h
+imc-dispatcher        1/1     1            1           42h
+```
+
+## Uninstall Knative
+
+### Removing the Knative Serving component
+
+Remove the Knative Serving CR:
+
+```
+kubectl delete KnativeServing knative-serving -n knative-serving
+```
+
+Knative Serving operator prevents unsafe removal of Knative serving resources. Even if the operator CR is successfully
+removed, all the CRDs in Knative Serving are still kept in the cluster. All your resources relying on Knative CRDs
+can still work.
+
+### Removing the Knative Serving Operator:
+
+If you have installed Knative Serving using the Release page, remove the operator using the following command:
+
+```
+kubectl delete -f https://github.com/knative/serving-operator/releases/download/v0.13.0/serving-operator.yaml
+```
+
+If you have installed Knative Serving from source, uninstall it using the following command while in the root directory
+for the source:
+
+```
+ko delete -f config/
+```
+
+### Removing Knative Eventing component
+
+Remove the Knative Eventing CR:
+
+```
+kubectl delete KnativeEventing knative-eventing -n knative-eventing
+```
+
+Knative Eventing operator also prevents unsafe removal of Knative Eventing resources by keeping the Knative Eventing CRDs.
+
+### Removing Knative Eventing Operator:
+
+If you have installed Knative Eventing using the Release page, remove the operator using the following command:
+
+```
+kubectl delete -f https://github.com/knative/eventing-operator/releases/download/v0.13.0/eventing-operator.yaml
+```
+
+If you have installed Knative Eventing from source, uninstall it using the following command while in the root directory
+for the source:
+
+```
+ko delete -f config/
+```