Verification

Check docker and docker-compose version:

docker -v
docker-compose -v

Run docker image test:

docker run hello-world

Status checks

List running containers:

docker ps

List all containers:

docker ps -a

Access to the container via bash.

Let's run Ubuntu container in the background and give the container a name for convenience:

docker run -dit --name container_no_1 ubuntu bash

Where:

• -d - run in the background (detached)
• -i - interactive mode
• -t - assign a pseudo-terminal
• --name container_no_1 - assigns a name to the container
• ubuntu bash - runs in the bash container (It is required in order to log in via bash)

And list running containers:

docker ps

To access via ssh, execute the following command:

docker exec -it container_no_1 bash

Useful docker compose commands

Stop all running containers:

docker stop $(docker ps -q)

Remove all containers:

docker rm $(docker ps -aq)

Utwórzmy defincję dwóch kontnerów, jeden z Tomcatem, drugi z bazą MariaDB. Remove all images

docker rmi $(docker images -q)

Force remove everything in one step

docker system prune -a --volumes

Docker Compose

If we want to define several connected containers, Docker Compose is a very good solution. Let us create definitions for two containers, one with Tomcat and the other with MariaDB, file docker-compose.yml:

version: '3.9'

services:
  tomcat:
    image: tomcat:10.1-jdk17
    container_name: tomcat_app
    restart: always
    ports:
      - "8080:8080"
    environment:
      - TZ=Europe/Warsaw
    depends_on:
      - mariadb
    volumes:
      - ./webapps:/usr/local/tomcat/webapps

  mariadb:
    image: mariadb:11.3
    container_name: mariadb_db
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=rootpassword
      - MYSQL_DATABASE=mydb
      - MYSQL_USER=myuser
      - MYSQL_PASSWORD=mypassword
      - TZ=Europe/Warsaw
    ports:
      - "3306:3306"
    volumes:
      - db_data:/var/lib/mysql

volumes:
  db_data:

In the directory wit the docker-compose.yml, run:

docker-compose up

Let's check if Tomcat is working. Enter the address of our host in the browser. If we are running locally, it is http://127.0.0.1:8080 (in my case, however, it is a remote machine http://192.168.3.112:8080):

Tomcat responds to the request. There is nothing on it, so we get a 404 code.

Let's connect to the MariaDB database:

mysql -h 127.0.0.1 -P 3306 -u myuser -p

The password is in the MYSQL_PASSWORD parameter.

Both containers are working. We can list them:

Links

Docker Engine
Docker Compose