serving/helloworld-php: Respect the PORT env var (#460)

* serving/helloworld-php: Respect the PORT env var

* serving/helloworld-php: add a comment to explain sed command

Author: grayside

serving/samples/helloworld-php/Dockerfile

@@ -2,5 +2,7 @@ FROM php:7.2.6-apache
 
 COPY index.php /var/www/html/
 
-# Run on port 8080 rather than 80
-RUN sed -i 's/80/8080/g' /etc/apache2/sites-available/000-default.conf /etc/apache2/ports.conf
+ENV PORT 8080
+
+# 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

serving/samples/helloworld-php/README.md

@@ -29,9 +29,8 @@ following instructions recreate the source files from this folder.
 
     ```php
     <?php
-      $target = getenv('TARGET', true) ?: "World";
-      echo sprintf("Hello %s!\n", $target);
-    ?>
+    $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.
@@ -42,8 +41,10 @@ following instructions recreate the source files from this folder.
 
     COPY index.php /var/www/html/
 
-    # Run on port 8080 rather than 80
-    RUN sed -i 's/80/8080/g' /etc/apache2/sites-available/000-default.conf /etc/apache2/ports.conf
+    ENV PORT 8080
+
+    RUN sed -i 's/80/${PORT}/g' /etc/apache2/sites-available/000-default.conf /etc/apache2/ports.conf
+
     ```
 
 1. Create a new file, `service.yaml` and copy the following service definition

serving/samples/helloworld-php/index.php

@@ -1,4 +1,3 @@
 <?php
-  $target = getenv('TARGET', true) ?: "World";
-  echo sprintf("Hello %s!\n", $target);
-?>
+$target = getenv('TARGET', true) ?: 'World';
+echo sprintf('Hello %s!\n', $target);