Hello World - PHP

A simple web app written in PHP 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 "main" https://github.com/knative/docs knative-docs
cd knative-docs/docs/serving/samples/hello-world/helloworld-php

Before you begin

  • A Kubernetes cluster with Knative installed and DNS configured. 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:

    $target = getenv('TARGET', true) ?: 'World';
    echo sprintf("Hello %s!\n", $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 7.3 image.
    # https://hub.docker.com/_/php
    FROM php:7.3-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.

  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/v1
    kind: Service
      name: helloworld-php
      namespace: default
            - image: docker.io/{username}/helloworld-php
                - 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

With kn you can deploy the service with

kn service create helloworld-php --image=docker.io/{username}/helloworld-php --env TARGET="Ruby Sample v1"

This will wait until your service is deployed and ready, and ultimately it will print the URL through which you can access the service.

The output will look like:

Creating service 'helloworld-php' in namespace 'default':

 0.035s The Configuration is still working to reflect the latest desired specification.
 0.139s The Route is still working to reflect the latest desired specification.
 0.250s Configuration "helloworld-php" is waiting for a Revision to become ready.
 8.040s ...
 8.136s Ingress has not yet been reconciled.
 8.277s unsuccessfully observed a new generation
 8.398s Ready to serve.

Service 'helloworld-php' created to latest revision 'helloworld-php-akhft-1' is available at URL:
  1. 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 a load balancer for your app.
    • Automatically scale your pods up and down (including to zero active pods).
  2. 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.
kn service describe helloworld-php -o url


  1. Now you can make a request to your app and see the result. Replace the URL below with the URL returned in the previous command.

    curl http://helloworld-php.default.
    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
kn service delete helloworld-php