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Knative Install using Gloo on a Kubernetes Cluster

This guide walks you through the installation of the latest version of Knative using pre-built images.

Before you begin

Knative requires a Kubernetes cluster v1.11 or newer with the MutatingAdmissionWebhook admission controller enabled. kubectl v1.10 is also required. This guide assumes that you've already created a Kubernetes cluster which you're comfortable installing alpha software on.

This guide assumes you are using bash in a Mac or Linux environment; some commands will need to be adjusted for use in a Windows environment.

Installing Glooctl

This installation method for Knative depends on Gloo. Run the following to install glooctl, the Gloo command line.

curl -sL https://run.solo.io/gloo/install | sh

Alternatively, you can download the Gloo CLI directly via the github releases page.

Next, add glooctl to your path with:

export PATH=$HOME/.gloo/bin:$PATH

Verify the CLI is installed and running correctly with:

glooctl --version

Installing Gloo and Knative to your cluster

Finally, install Gloo and Knative in a single command with glooctl:

glooctl install knative

Note: To see the content of the kubernetes manifest glooctl installs, run glooctl install knative --dry-run. Monitor the Gloo components until all of the components show a STATUS of Running or Completed:

kubectl get pods --namespace gloo-system
kubectl get pods --namespace knative-serving

It will take a few minutes for all the components to be up and running; you can rerun the command to see the current status.

Note: Instead of rerunning the command, you can add --watch to the above commands to view the component's status updates in real time. Use CTRL+C to exit watch mode.

Now you can deploy an app using your freshly installed Knative environment.

Deploying an app

Now that your cluster has Knative installed, you can see what Knative has to offer.

To deploy your first app with Knative, follow the step-by-step Getting Started with Knative App Deployment guide.

Note that when you've finished deploying the app, you'll need to connect to the Gloo Gateway rather than the Istio Gateway.

To get the URL of the Gloo Gateway, run

export GATEWAY_URL=$(glooctl proxy url --name clusteringress-proxy)

echo $GATEWAY_URL
http://192.168.99.230:31864

To send requests to your service:

export GATEWAY_URL=$(glooctl proxy url --name clusteringress-proxy)

curl -H "Host: helloworld-go.myproject.example.com" $GATEWAY_URL

The full instructions for the Go Hello-World Sample with this substitution are published bellow:

Deploy the Hello-World Go App:

Create a new file named helloworld.go and paste the following code. This code creates a basic web server which listens on port 8080:

package main

import (
    "fmt"
    "log"
    "net/http"
    "os"
)

func handler(w http.ResponseWriter, r *http.Request) {
    log.Print("Hello world received a request.")
    target := os.Getenv("TARGET")
    if target == "" {
        target = "World"
    }
    fmt.Fprintf(w, "Hello %s!\n", target)
}

func main() {
    log.Print("Hello world sample started.")

    http.HandleFunc("/", handler)

    port := os.Getenv("PORT")
    if port == "" {
        port = "8080"
    }

    log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))
}

In your project directory, create a file named Dockerfile and copy the code block below into it. For detailed instructions on dockerizing a Go app, see Deploying Go servers with Docker.

# Use the official Golang image to create a build artifact.
# This is based on Debian and sets the GOPATH to /go.
# https://hub.docker.com/_/golang
FROM golang as builder

# Copy local code to the container image.
WORKDIR /go/src/github.com/knative/docs/helloworld
COPY . .

# Build the helloworld command inside the container.
# (You may fetch or manage dependencies here,
# either manually or with a tool like "godep".)
RUN CGO_ENABLED=0 GOOS=linux go build -v -o helloworld

# Use a Docker multi-stage build to create a lean production image.
# https://docs.docker.com/develop/develop-images/multistage-build/#use-multi-stage-builds
FROM alpine

# Copy the binary to the production image from the builder stage.
COPY --from=builder /go/src/github.com/knative/docs/helloworld/helloworld /helloworld

# Service must listen to $PORT environment variable.
# This default value facilitates local development.
ENV PORT 8080

# Run the web service on container startup.
CMD ["/helloworld"]

Create a new file, service.yaml and copy the following service definition into the file. Make sure to replace {username} with your Docker Hub username.

apiVersion: serving.knative.dev/v1alpha1
kind: Service
metadata:
  name: helloworld-go
  namespace: default
spec:
  runLatest:
    configuration:
      revisionTemplate:
        spec:
          container:
            image: docker.io/{username}/helloworld-go
            env:
              - name: TARGET
                value: "Go Sample v1"

Once the sample code has been created, we'll build and deploy it

Use Docker to build the sample code into a container. To build and push with Docker Hub, run these commands replacing {username} with your Docker Hub username:

# Build the container on your local machine
docker build -t {username}/helloworld-go .

# Push the container to docker registry
docker push {username}/helloworld-go

After the build has completed and the container is pushed to docker hub, you can deploy the app into your cluster. Ensure that the container image value in service.yaml matches the container you built in the previous step. Apply the configuration using kubectl:

kubectl apply --filename service.yaml

Now that your service is created, Knative will perform the following steps:

  • Create a new immutable revision for this version of the app.

  • Network programming to create a route, ingress, service, and load balance for your app.

  • Automatically scale your pods up and down (including to zero active pods).

  • Run the following command to find the external IP address for the Gloo cluster ingress.

CLUSTERINGRESS_URL=$(glooctl proxy url --name clusteringress-proxy)
echo $CLUSTERINGRESS_URL
http://192.168.99.230:31864

Run the following command to find the domain URL for your service:

kubectl get ksvc helloworld-go -n default  --output=custom-columns=NAME:.metadata.name,DOMAIN:.status.domain

Example:

NAME                DOMAIN
helloworld-go       helloworld-go.default.example.com

Test your app by sending it a request. Use the following curl command with the domain URL helloworld-go.default.example.com and EXTERNAL-IP address that you retrieved in the previous steps:

curl -H "Host: helloworld-go.default.example.com" ${CLUSTERINGRESS_URL}
Hello Go Sample v1!

Note: Add -v option to get more detail if the curl command failed.

Removing the sample app deployment
To remove the sample app from your cluster, delete the service record:

kubectl delete --filename service.yaml

Great! our Knative ingress is up and running. See https://github.com/knative/docs for more information on using Knative.