ZSI / Docker

Concepts

• Container — virtual environment for running application
• Image — template for creating containers
• Registry — storage for images
  • https://hub.docker.com/
  • GitHub, GitLab, etc.

Example — src/index.php

<?php
echo("Hello world!");

Dependencies:

• PHP
• Apache

Dockerfile — instructions for building image

FROM php:7.2-apache-stretch
COPY src /var/www/html

• Official Images: https://hub.docker.com/search?image_filter=official

Build image and start container

$ docker build  -t hello-php  .
$ docker run  -p 8000:80  --name running-hello  hello-php

Other commands

• docker container ls
• docker container stop / start
• docker container rm
• docker image ls
• docker image rm
• docker system prune
• Documentation: https://docs.docker.com/reference/cli/docker/

Layers

• a layer for each command in Dockerfile
  • read-only
• container — temporary read-write layer
• copy-on-write
• identical layers are shared

Persistent data storage — volumes

• anonymous volumes
• named volumes -v <volume-name>:<container-path>
• bind mounts -v <host-path>:<container-path>
• https://docs.docker.com/storage/

Dockerfile

FROM php:7.2-apache-stretch
COPY src /var/www/html
VOLUME /var/www/html/uploads

In development

Bind mount

• Unix:

docker run -p 8000:80 -v "$(pwd)"/src:/var/www/html hello-php

• Windows:

docker run -p 8000:80 -v d:/hello/src:/var/www/html hello-php

Let’s connect to database

<?php
$conn = new mysqli(
    "db-server", "user", "my-password", "hello");
if ($conn->connect_error)
    die("Oh, no! Connection failed!");
echo "Hello MariaDB!";

Dockerfile

FROM php:7.2-apache-stretch
RUN docker-php-ext-install mysqli
COPY src /var/www/html

We need to run a database server

Docker Compose

• Definition of multiple containers
• Manipulation with the group of containers
• Documentation: https://docs.docker.com/compose/

compose.yaml

services:
    web:
        build: .
        image: hello-php
        ports:
            - "8000:80"
        volumes:
            - ./src:/var/www/html

    db-server:
        image: mariadb:10.3
        environment:
            MYSQL_ROOT_PASSWORD: my-root-pwd
            MYSQL_DATABASE: hello
            MYSQL_USER: user
            MYSQL_PASSWORD: my-password

Up!

$ docker compose build web
$ docker compose up
$ docker compose down

Examples