mirror of https://github.com/knative/docs.git
163 lines
4.8 KiB
Markdown
163 lines
4.8 KiB
Markdown
# Hello World - Ruby sample
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A simple wenb app written in Ruby that you can use for testing.
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It reads in an env variable `TARGET` and prints "Hello World: ${TARGET}!". If
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TARGET is not specified, it will use "NOT SPECIFIED" as the TARGET.
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## Prerequisites
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* A Kubernetes cluster with Knative installed. Follow the
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[installation instructions](https://github.com/knative/install/) if you need
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to create one.
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* [Docker](https://www.docker.com) installed and running on your local machine,
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and a Docker Hub account configured (we'll use it for a container registry).
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## Steps to recreate the sample code
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While you can clone all of the code from this directory, hello world apps are
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generally more useful if you build them step-by-step.
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The following instructions recreate the source files from this folder.
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1. Create a new directory and cd into it:
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````shell
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mkdir app
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cd app
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````
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1. Create a file named `app.rb` and copy the code block below into it:
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```ruby
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require 'sinatra'
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set :bind, '0.0.0.0'
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get '/' do
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target = ENV['TARGET'] || 'NOT SPECIFIED'
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"Hello World: #{target}!\n"
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end
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```
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1. Create a file named `Dockerfile` and copy the code block below into it.
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See [official Ruby docker image](https://hub.docker.com/_/ruby/) for more details.
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```docker
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FROM ruby
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RUN bundle config --global frozen 1
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WORKDIR /usr/src/app
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COPY Gemfile Gemfile.lock ./
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RUN bundle install
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COPY . .
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ENV PORT 8080
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EXPOSE 8080
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CMD ["ruby", "./app.rb"]
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```
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1. Create a file named `Gemfile` and copy the text block below into it.
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```gem
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source 'https://rubygems.org'
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gem 'sinatra'
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```
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1. Run bundle. If you don't have bundler installed, copy the
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[Gemfile.lock](./Gemfile.lock) to your working directory.
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```shell
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bundle install
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```
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1. Create a new file, `service.yaml` and copy the following service definition
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into the file. Make sure to replace `{username}` with your Docker Hub username.
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```yaml
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apiVersion: serving.knative.dev/v1alpha1
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kind: Service
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metadata:
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name: helloworld-ruby
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namespace: default
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spec:
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runLatest:
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configuration:
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revisionTemplate:
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spec:
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container:
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image: docker.io/{username}/helloworld-ruby
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env:
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- name: TARGET
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value: "Ruby Sample v1"
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```
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## Build and deploy this sample
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Once you have recreated the sample code files (or used the files in the sample folder)
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you're ready to build and deploy the sample app.
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1. Use Docker to build the sample code into a container. To build and push with
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Docker Hub, run these commands replacing `{username}` with your
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Docker Hub username:
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```shell
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# Build the container on your local machine
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docker build -t {username}/helloworld-ruby .
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# Push the container to docker registry
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docker push {username}/helloworld-ruby
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```
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1. After the build has completed and the container is pushed to docker hub, you
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can deploy the app into your cluster. Ensure that the container image value
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in `service.yaml` matches the container you built in
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the previous step. Apply the configuration using `kubectl`:
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```shell
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kubectl apply -f service.yaml
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```
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1. Now that your service is created, Knative will perform the following steps:
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* Create a new immutable revision for this version of the app.
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* Network programming to create a route, ingress, service, and load balance for your app.
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* Automatically scale your pods up and down (including to zero active pods).
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1. To find the IP address for your service, use
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`kubectl get svc knative-ingressgateway -n istio-system` to get the ingress IP for your
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cluster. If your cluster is new, it may take sometime for the service to get asssigned
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an external IP address.
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```shell
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kubectl get svc knative-ingressgateway -n istio-system
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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knative-ingressgateway LoadBalancer 10.23.247.74 35.203.155.229 80:32380/TCP,443:32390/TCP,32400:32400/TCP 2d
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```
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1. To find the URL for your service, use
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```
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kubectl get services.serving.knative.dev helloworld-ruby -o=custom-columns=NAME:.metadata.name,DOMAIN:.status.domain
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NAME DOMAIN
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helloworld-ruby helloworld-ruby.default.example.com
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```
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1. Now you can make a request to your app to see the result. Replace `{IP_ADDRESS}`
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with the address you see returned in the previous step.
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```shell
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curl -H "Host: helloworld-ruby.default.example.com" http://{IP_ADDRESS}
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Hello World: Ruby Sample v1!
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```
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## Remove the sample app deployment
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To remove the sample app from your cluster, delete the service record:
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```shell
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kubectl delete -f service.yaml
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```
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