add docker-compose.yml to php example

example-php-apache/README.md

@@ -5,20 +5,28 @@ Follow these steps to start the php server:
 ```
 cd /path/to/example-php-apache
 docker build -t example-php-apache-img .
-docker run -p 3000:80 -v $(pwd)/src:/var/www/html --name example-php-apache-container example-php-apache-img
+docker run -p 8000:80 -v $(pwd)/src:/var/www/html --name example-php-apache-container example-php-apache-img
 ```
 
 Open up the following url in your browser:
 
-- http://localhost:3000
+- http://localhost:8000
 
 
-# Notes
+#### Notes about `docker run`:
 
-In the `docker run` command:
 - `-p` maps ports like so: `<MACHINE_PORT>:<CONTAINER_PORT>`
 - `-v` specifies the volume to enable realtime updates in local dev environment.
   - The volume must be specified at runtime in order for this to work. [See documentation](https://docs.docker.com/engine/reference/builder/#notes-about-specifying-volumes) for more details.
   - The host volume mount src MUST be absolute, not relative
   - `$(pwd)` just outputs the absolute path of the present working directory
   - Volumes have ZERO effect once deployed (except for sharing filesystems across several containers)
+
+## Docker Compose
+
+All of the above can steps can be simplified into a single cmd that utilizes docker compose:
+
+```
+cd /path/to/example-php-apache
+docker-compose up
+```

example-php-apache/docker-compose.yml

@@ -0,0 +1,9 @@
+version: "3"
+
+services:
+  webapp:
+    build: .
+    volumes:
+      - ./src:/var/www/html
+    ports:
+      - "8000:80"