Build Custom Images With Dockerfiles and Docker-Compose¶

In this lecture we're going beyond just orchestration, we customize what needs to be orchestrated.

Build your own images with custom configuration using docker compose and the docker-compose.yml file¶

Now you know two things: 1. You can use a Dockerfile to generate an image 2. You can mount folders inside your directory automatically into the container

We're one step close to building our dream dev-environment!

What if we desperately need a different configuration than provided in the php:7.2-apache image? We change it and rebuild it using our own Dockerfile into our own image.

Use this docker-compose.yml file:

version: '3'

services:
  phpapp:
    build:
      context: ./
      dockerfile: Dockerfile
    image: phpapp:123
    ports:
      - "8080:80"
    volumes:
      - "./:/var/www/html"
    container_name: my-php-app

And this Dockerfile for starter:

FROM php:7.2-apache

And this index.php:

<?php

phpinfo();

Then head to the terminal and type in:

docker-compose up

Observe that the image gets built
The image name is "phpapp:123" and not the [folder-name]_[service-name] anymore.
It mounts again the volume
It forwards the port 80
And the container name is my-php-app

Open http://localhost:8080. It should show you the php information.

This isn't really impressive yet. But what if you desperately need mysqli and the php-intl extension installed inside your docker container. Surely you can enter the container by docker exec -it my-php-app /bin/bash and then apt-get install etc... but there is a better way. Why not directly embed it into the image of the container?

Stop the container: ctrl-c

docker-compose rm

* Remove the container

Extend the Dockerfile so that it looks like this:

FROM php:7.2-apache

RUN apt-get -y update \
&& apt-get install -y libicu-dev \ 
&& docker-php-ext-configure intl \
&& docker-php-ext-install intl

RUN docker-php-ext-install mysqli && docker-php-ext-enable mysqli

No PHP Knowledge needed

You don't really need to know what exactly is going on here in terms of PHP internals. What you need to understand is that something gets installed at build-time rather than starting the container. There is something that is installed permanently into the image.

Then run

docker-compose up --build

This should rebuild your containers
You should see a lot of compiler-output
Once done it should open apache
Open http://localhost:8080 and text-search for "mysqli" and "intl". There should be these packages available now.

Stop the container: Ctrl-c

docker-compose rm

remove the container