Kourier Installation guide for Knative Serving (#2006)

* Adds a new guide describing how to install knative with kourier

* Links the knative with kourier installation guide in the main README file

* Use kourier-system instead of knative-serving when getting kourier IP

* Install Kourier using the included yaml in third_party

docs/install/README.md

@@ -62,6 +62,10 @@ There are several options when installing Knative:
 For new users, we recommend the comprehensive install to get you up and running
 quickly.
 
+## Installing Knative with Kourier
+
+[Installing Knative with Kourier](./knative-with-kourier.md): In this guide, Knative will be installed with Kourier to replace the Istio Service Mesh, providing a more lightweight and simple Ingress controller. Note that Istio is required for the Knative Eventing component.
+
 ### Install guides
 
 Follow these step-by-step guides for setting up Kubernetes and installing

docs/install/knative-with-kourier.md

@@ -0,0 +1,162 @@
+---
+title: "Installing Knative with Kourier"
+linkTitle: "Kourier Ingress and Knative"
+weight: 15
+type: "docs"
+---
+
+[Kourier](https://github.com/3scale/kourier) is an open-source lightweight Knative Ingress based on Envoy. It's been designed for Knative, without requiring any additional custom resource definitions (CRDs).
+
+This guide walks you through the installation of the latest version of Knative
+with Kourier as the ingress.
+
+## Before you Begin
+
+Knative requires a Kubernetes cluster v1.14 or newer, as well as a compatible `kubectl`. This guide assumes that you have already [created a Kubernetes cluster](https://kubernetes.io/docs/setup/) and are using
+bash in a Mac or Linux environment.
+
+## Install Knative
+
+Let's do a core install of Knative Serving with the released yaml templates:
+
+1.  To install Knative, first install the CRDs by running the following `kubectl apply`
+    command. This prevents race conditions during the install, which cause intermittent errors:
+
+        kubectl apply --filename https://github.com/knative/serving/releases/download/{{< version >}}/serving-crds.yaml
+
+1.  To complete the install of Knative and its dependencies, next run the
+    following `kubectl apply` command:
+
+        kubectl apply --filename https://github.com/knative/serving/releases/download/{{< version >}}/serving-core.yaml
+
+1.  Monitor the Knative Serving namespace and wait until all of the pods come up with a
+    `STATUS` of `Running`:
+
+    ```
+    kubectl get pods -w -n knative-serving
+    ```
+
+
+## Install Kourier
+
+Knative default installation uses Istio to handle internal and external traffic. If you are just interested in exposing Knative applications to the external network, a service mesh adds overhead and increases the system complexity. Kourier provides a way to expose your Knative application in a more simple and lightweight way.
+
+You can install Kourier with `kubectl`:
+
+```
+kubectl apply \
+  --filename https://raw.githubusercontent.com/knative/serving/{{< version >}}/third_party/kourier-latest/kourier.yaml
+```
+
+## Configuring the Knative ingress class
+
+Kourier only exposes ingresses that have the "kourier" ingress class. By default Knative annotates all the ingresses for Istio but you can change that by patching the "config-network" configmap as follows: 
+
+```
+kubectl patch configmap/config-network \
+  -n knative-serving \
+  --type merge \
+  -p '{"data":{"ingress.class":"kourier.ingress.networking.knative.dev"}}'
+```
+
+## Configuring DNS
+
+Installing Kourier will create a Kubernetes Service with type `LoadBalancer`.
+This may take some time to get an IP address assigned, during this process, it
+will appear as `<pending>`.  You must wait for this IP address to be assigned
+before DNS may be set up.
+
+To get the external IP address, use the following command:
+
+```
+kubectl get svc kourier -n kourier-system
+
+NAME         TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)        AGE
+kourier      LoadBalancer   10.43.242.100  172.22.0.2      80:31828/TCP   19m
+
+```
+
+This external IP can be used with your DNS provider with a wildcard `A` record;
+however, for a basic functioning DNS setup (not suitable for production!) this
+external IP address can be added to the `config-domain` ConfigMap in
+`knative-serving`. You can edit this with the following command:
+
+```
+kubectl edit cm config-domain --namespace knative-serving
+```
+
+Given the external IP above, change the content to:
+
+```
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: config-domain
+  namespace: knative-serving
+data:
+  # xip.io is a "magic" DNS provider, which resolves all DNS lookups for:
+  # *.{ip}.xip.io to {ip}.
+  172.22.0.2.xip.io: ""
+```
+
+## Deploying an Application
+
+Now that Kourier is running and Knative is configured properly, you can go ahead and create your first Knative application:
+
+1. Create a `Knative Service`
+
+   For this demo, a simple helloworld application written in go will be used.
+   Copy the YAML below to a file called `helloworld-go.yaml` and apply it with
+   `kubectl`
+
+   ```yaml
+   apiVersion: serving.knative.dev/v1
+   kind: Service
+   metadata:
+     name: helloworld-go
+     namespace: default
+   spec:
+     template:
+       spec:
+         containers:
+           - image: gcr.io/knative-samples/helloworld-go
+             env:
+               - name: TARGET
+                 value: Go Sample v1
+   ```
+
+   ```
+   kubectl apply -f helloworld-go.yaml
+   ```
+
+1. Send a request
+
+   `Knative Service`s are exposed via a `Host` header assigned by Knative. By
+   default, Knative will assign the `Host`:
+   `{service-name}.{namespace}.{the domain we have setup above}`.  You can see this
+   with:
+
+   ```
+   $ kubectl get ksvc helloworld-go
+   NAME            URL                                                LATESTCREATED         LATESTREADY           READY     REASON
+   helloworld-go   http://helloworld-go.default.172.22.0.2.xip.io   helloworld-go-ps7lp   helloworld-go-ps7lp   True
+   ```
+
+   You can send a request to the `helloworld-go` service with curl
+   using the `URL` given above:
+
+   ```
+   $ curl http://helloworld-go.default.172.22.0.2.xip.io
+
+   Hello Go Sample v1!
+   ```
+
+Congratulations! You have successfully installed Knative with Kourier to manage and route your serverless applications!
+
+## What's next
+
+- Try the
+  [Getting Started with App Deployment guide](../serving/getting-started-knative-app.md)
+  for Knative serving.
+- Get started with Knative Eventing by walking through one of the
+  [Eventing Samples](../eventing/samples/).