Docker : Use Docker Compose2021/08/30

	To Install Docker Compose, it's easy to configure and run multiple containers as a Docker application.
[1]	Install Docker Compose.

root@dlp:~#

apt -y install docker-compose

[2]	For example, Configure an application that has Web and DB services with Docker Compose.

# define Web service container

root@dlp:~#

vi Dockerfile

FROM debian
MAINTAINER ServerWorld <admin@srv.world>

ENV DEBIAN_FRONTEND=noninteractive

RUN apt-get update
RUN apt-get -y install apache2

EXPOSE 80
CMD ["/usr/sbin/apachectl", "-D", "FOREGROUND"]

# define application configration

root@dlp:~#

vi docker-compose.yml

version: '3'
services:
  db:
    image: mariadb
    volumes:
      - /var/lib/docker/disk01:/var/lib/mysql
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_USER: bullseye
      MYSQL_PASSWORD: password
      MYSQL_DATABASE: bullseye_db
    ports:
      - "3306:3306"
  web:
    build: .
    ports:
      - "80:80"
    volumes:
      - /var/lib/docker/disk02:/var/www/html

# buid and run

root@dlp:~#

docker-compose up -d

Creating network "root_default" with the default driver
Building web
Step 1/7 : FROM debian
 ---> fe3c5de03486
Step 2/7 : MAINTAINER ServerWorld <admin@srv.world>
 ---> Using cache
 ---> 7327e34c8977
Step 3/7 : ENV DEBIAN_FRONTEND=noninteractive
 ---> Running in 2d9696af1448

.....
.....

Creating root_db_1  ... done
Creating root_web_1 ... done

root@dlp:~#

docker ps

CONTAINER ID   IMAGE      COMMAND                  CREATED              STATUS              PORTS                    NAMES
d3077533ab0e   root_web   "/usr/sbin/apachectl…"   About a minute ago   Up About a minute   0.0.0.0:80->80/tcp       root_web_1
9aa6dc83c5de   mariadb    "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:3306->3306/tcp   root_db_1

# verify accesses

root@dlp:~#

mysql -h 127.0.0.1 -u root -p -e "show variables like 'hostname';"

Enter password:
+---------------+--------------+
| Variable_name | Value        |
+---------------+--------------+
| hostname      | 9aa6dc83c5de |
+---------------+--------------+

root@dlp:~#

mysql -h 127.0.0.1 -u bullseye -p -e "show databases;"

Enter password:
+--------------------+
| Database           |
+--------------------+
| bullseye_db        |
| information_schema |
+--------------------+

root@dlp:~#

echo "Hello Docker Compose World" > /var/lib/docker/disk02/index.html

root@dlp:~#

curl 127.0.0.1

Hello Docker Compose World

[3]	Other basic operations of Docker Compose are follows.

# verify state of containers

root@dlp:~#

docker-compose ps

   Name                 Command               State           Ports
----------------------------------------------------------------------------
root_db_1    docker-entrypoint.sh mysqld      Up      0.0.0.0:3306->3306/tcp
root_web_1   /usr/sbin/apachectl -D FOR ...   Up      0.0.0.0:80->80/tcp

# show logs of containers

root@dlp:~#

docker-compose logs

Attaching to root_web_1, root_db_1
db_1   | 2021-08-30 01:02:52+00:00 [Note] [Entrypoint]: Entrypoint script for MariaDB Server 1:10.6.4+maria~focal started.
db_1   | 2021-08-30 01:02:52+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
db_1   | 2021-08-30 01:02:52+00:00 [Note] [Entrypoint]: Entrypoint script for MariaDB Server 1:10.6.4+maria~focal started.

.....
.....

db_1   | 2021-08-30  1:03:02 0 [Warning] 'proxies_priv' entry '@% root@9aa6dc83c5de' ignored in --skip-name-resolve mode.
db_1   | 2021-08-30  1:03:02 0 [Note] mysqld: ready for connections.
db_1   | Version: '10.6.4-MariaDB-1:10.6.4+maria~focal'  socket: '/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution
web_1  | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.18.0.2. Set the 'ServerName' directive globally to suppress this message

# run any commands inside a container
# container name is just the one set in [docker-compose.yml]

root@dlp:~#

docker-compose exec db /bin/bash

root@9aa6dc83c5de:/#

# stop application and also shutdown all containers

root@dlp:~#

docker-compose stop

Stopping root_db_1  ... done
Stopping root_web_1 ... done

# start a service alone in application
# if set dependency, other container starts

root@dlp:~#

docker-compose up -d web

Starting root_web_1 ... done

root@dlp:~#

docker-compose ps

   Name                 Command               State          Ports
-------------------------------------------------------------------------
root_db_1    docker-entrypoint.sh mysqld      Exit 0
root_web_1   /usr/sbin/apachectl -D FOR ...   Up       0.0.0.0:80->80/tcp

# remove all containers in application
# if a container is running, it won't be removed

root@dlp:~#

docker-compose rm

Going to remove root_db_1
Are you sure? [yN] y
Removing root_db_1 ... done

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