# Hello World - PHP sample

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.

## Prerequisites

- A Kubernetes cluster with Knative installed. Follow the
  [installation instructions](https://github.com/knative/docs/blob/master/install/README.md)
  if you need to create one.
- [Docker](https://www.docker.com) 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

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:

   ```shell
   mkdir app
   cd app
   ```

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

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

1. Create a file named `Dockerfile` and copy the code block below into it. See
   [official PHP docker image](https://hub.docker.com/_/php/) for more details.

   ```docker
   # Use the official PHP 7.2 image.
   # https://hub.docker.com/_/php
   FROM php:7.2.6-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 and document the service HTTP port.
   ENV PORT 8080
   EXPOSE $PORT
   ```

1. 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.

   ```yaml
   apiVersion: serving.knative.dev/v1alpha1
   kind: Service
   metadata:
     name: helloworld-php
     namespace: default
   spec:
     runLatest:
       configuration:
         revisionTemplate:
           spec:
             container:
               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:

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

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

1. 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`:

   ```shell
   kubectl apply --filename service.yaml
   ```

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 load balance
     for your app.
   - Automatically scale your pods up and down (including to zero active pods).

1. To find the IP address for your service, use
   `kubectl get svc knative-ingressgateway --namespace 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.

   ```shell
   kubectl get svc knative-ingressgateway --namespace 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

   ```

1. To find the URL for your service, use

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

1. 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.

   ```shell
   curl -H "Host: helloworld-php.default.example.com" http://{IP_ADDRESS}
   Hello World: PHP Sample v1!
   ```

## Removing the sample app deployment

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

```shell
kubectl delete --filename service.yaml
```