Skip to content

Latest commit

 

History

History
167 lines (124 loc) · 5.2 KB

README.md

File metadata and controls

167 lines (124 loc) · 5.2 KB

Hello World - Ruby sample

A simple wenb app written in Ruby that you can use for testing. It reads in an env variable TARGET and prints "Hello World: ${TARGET}!". If TARGET is not specified, it will use "NOT SPECIFIED" as the TARGET.

Prerequisites

  • A Kubernetes cluster with Knative installed. Follow the installation instructions if you need to create one.
  • Docker installed and running on your local machine, and a Docker Hub account configured (we'll use it for a container registry).

Steps to recreate the sample code

While you can clone all of the code from this directory, hello world apps are generally more useful if you build them step-by-step. The following instructions recreate the source files from this folder.

  1. Create a new directory and cd into it:

    mkdir app
cd app

  2. Create a file named app.rb and copy the code block below into it:

    require 'sinatra'

set :bind, '0.0.0.0'

get '/' do
  target = ENV['TARGET'] || 'NOT SPECIFIED'
  "Hello World: #{target}!\n"
end

  3. Create a file named Dockerfile and copy the code block below into it. See official Ruby docker image for more details.

    FROM ruby

RUN bundle config --global frozen 1

WORKDIR /usr/src/app
COPY Gemfile Gemfile.lock ./
RUN bundle install

COPY . .

ENV PORT 8080
EXPOSE 8080

CMD ["ruby", "./app.rb"]

  4. Create a file named Gemfile and copy the text block below into it.

    source 'https://rubygems.org'

gem 'sinatra'

  5. Run bundle. If you don't have bundler installed, copy the Gemfile.lock to your working directory.

    bundle install

  6. 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-ruby
  namespace: default
spec:
  runLatest:
    configuration:
      revisionTemplate:
        spec:
          container:
            image: docker.io/{username}/helloworld-ruby
            env:
            - name: TARGET
              value: "Ruby Sample v1"

Build and deploy this sample

Once you have recreated the sample code files (or used the files in the sample folder) you're ready to build and deploy the sample app.

  1. 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-ruby .

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

  2. 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 -f service.yaml

  3. 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).

  4. To find the IP address for your service, use kubectl get svc knative-ingressgateway -n istio-system to get the ingress IP for your cluster. If your cluster is new, it may take sometime for the service to get asssigned an external IP address.

    kubectl get svc knative-ingressgateway -n istio-system

NAME                     TYPE           CLUSTER-IP     EXTERNAL-IP      PORT(S)                                      AGE
knative-ingressgateway   LoadBalancer   10.23.247.74   35.203.155.229   80:32380/TCP,443:32390/TCP,32400:32400/TCP   2d

  5. To find the URL for your service, use

    kubectl get ksvc helloworld-ruby  -o=custom-columns=NAME:.metadata.name,DOMAIN:.status.domain
NAME                DOMAIN
helloworld-ruby     helloworld-ruby.default.example.com

    Note: ksvc is an alias for services.serving.knative.dev. If you have an older version (version 0.1.0) of Knative installed, you'll need to use the long name until you upgrade to version 0.1.1 or higher. See Checking Knative Installation Version to learn how to see what version you have installed.

  6. Now you can make a request to your app to see the result. Replace {IP_ADDRESS} with the address you see returned in the previous step.

    curl -H "Host: helloworld-ruby.default.example.com" http://{IP_ADDRESS}
Hello World: Ruby Sample v1!

Remove the sample app deployment

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

kubectl delete -f service.yaml