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

Follow the steps below to create the sample code and then deploy the app to your cluster. You can also download a working copy of the sample, by running the following commands:

git clone -b "release-0.7" https://github.com/knative/docs knative-docs
cd knative-docs/serving/samples/hello-world/helloworld-php

Before you begin

• 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).

Recreating the sample code

1. Create a new directory and cd into it:

   mkdir app
   cd app

2. Create a file named index.php and copy the code block below into it:

   <?php
   $target = getenv('TARGET', true) ?: 'World';
   echo sprintf("Hello %s!", $target);

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

   # Use the official PHP 7.2 image.
   # https://hub.docker.com/_/php
   FROM php:7.2-apache
   
   # Copy local code to the container image.
   COPY index.php /var/www/html/
   
   # Use the PORT environment variable in Apache configuration files.
   RUN sed -i 's/80/${PORT}/g' /etc/apache2/sites-available/000-default.conf /etc/apache2/ports.conf
   
   # Configure PHP for development.
   # Switch to the production php.ini for production operations.
   # RUN mv "$PHP_INI_DIR/php.ini-production" "$PHP_INI_DIR/php.ini"
   # https://hub.docker.com/_/php#configuration
   RUN mv "$PHP_INI_DIR/php.ini-development" "$PHP_INI_DIR/php.ini"
   

4. Create a .dockerignore file to ensure that any files related to a local build do not affect the container that you build for deployment.

   Dockerfile
   README.md
   vendor

5. 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-php
     namespace: default
   spec:
     template:
       spec:
         containers:
           - image: docker.io/{username}/helloworld-php
             env:
               - name: TARGET
                 value: "PHP Sample v1"

Building and deploying the 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-php .
   
   # Push the container to docker registry
   docker push {username}/helloworld-php

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 --filename 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 these commands 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.

   # In Knative 0.2.x and prior versions, the `knative-ingressgateway` service was used instead of `istio-ingressgateway`.
   INGRESSGATEWAY=knative-ingressgateway
   
   # The use of `knative-ingressgateway` is deprecated in Knative v0.3.x.
   # Use `istio-ingressgateway` instead, since `knative-ingressgateway`
   # will be removed in Knative v0.4.
   if kubectl get configmap config-istio -n knative-serving &> /dev/null; then
      INGRESSGATEWAY=istio-ingressgateway
   fi
   
   kubectl get svc $INGRESSGATEWAY --namespace istio-system
   
   NAME                     TYPE           CLUSTER-IP     EXTERNAL-IP      PORT(S)                                      AGE
   xxxxxxx-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-php  --output=custom-columns=NAME:.metadata.name,URL:.status.url
   NAME                URL
   helloworld-php      http://helloworld-php.default.example.com
   

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-php.default.example.com" http://{IP_ADDRESS}
   Hello PHP Sample v1!

Removing the sample app deployment

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

kubectl delete --filename service.yaml