Docker : Use Docker Compose2022/07/29

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

[root@dlp ~]#

curl -L https://github.com/docker/compose/releases/download/v2.7.0/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose

[root@dlp ~]#

chmod 755 /usr/local/bin/docker-compose

[root@dlp ~]#

docker-compose --version

Docker Compose version v2.7.0

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

# define Web service container

[root@dlp ~]#

vi Dockerfile

FROM quay.io/centos/centos:stream9
MAINTAINER ServerWorld <admin@srv.world>

RUN dnf -y install nginx

EXPOSE 80
CMD ["/usr/sbin/nginx", "-g", "daemon off;"]

# define application configuration

[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: cent
      MYSQL_PASSWORD: password
      MYSQL_DATABASE: cent_db
    ports:
      - "3306:3306"
  web:
    build: .
    ports:
      - "80:80"
    volumes:
      - /var/lib/docker/disk02:/usr/share/nginx/html

# build and run

[root@dlp ~]#

docker-compose up -d

[+] Running 12/12
[+] Building 0.1s (4/5)
 => [internal] load build definition from Dockerfile                       0.0s
 => => transferring dockerfile: 257B                                       0.0s
 
.....
.....

[+] Running 3/3eth0: renamed from vethd22d159
  Network root_default  Created 0.2sCHANGE): veth34f9937: link becomes ready
  Container root-db-1   Started 0.5ss(veth34f9937) entered blocking state
  Container root-web-1  Started 0.5ss(veth34f9937) entered forwarding state

[root@dlp ~]#

docker ps

CONTAINER ID   IMAGE      COMMAND                  CREATED          STATUS          PORTS                                       NAMES
4e9bdc02dd9a   mariadb    "docker-entrypoint.s…"   18 seconds ago   Up 16 seconds   0.0.0.0:3306->3306/tcp, :::3306->3306/tcp   root-db-1
29dcae4b111e   root_web   "/usr/sbin/nginx -g …"   18 seconds ago   Up 17 seconds   0.0.0.0:80->80/tcp, :::80->80/tcp           root-web-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      | 4e9bdc02dd9a |
+---------------+--------------+

[root@dlp ~]#

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

Enter password:
+--------------------+
| Database           |
+--------------------+
| cent_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                  SERVICE             STATUS              PORTS
root-db-1           "docker-entrypoint.s…"   db                  running             0.0.0.0:3306->3306/tcp, :::3306->3306/tcp
root-web-1          "/usr/sbin/nginx -g …"   web                 running             0.0.0.0:80->80/tcp, :::80->80/tcp

# show logs of containers

[root@dlp ~]#

docker-compose logs

root-db-1  | 2022-07-29 04:57:23+00:00 [Note] [Entrypoint]: Entrypoint script for MariaDB Server 1:10.8.3+maria~jammy started.
root-db-1  | 2022-07-29 04:57:23+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
root-db-1  | 2022-07-29 04:57:23+00:00 [Note] [Entrypoint]: Entrypoint script for MariaDB Server 1:10.8.3+maria~jammy started.

.....
.....

root-db-1  | 2022-07-29  4:57:29 0 [Note] Server socket created on IP: '::'.
root-db-1  | 2022-07-29  4:57:29 0 [Note] mariadbd: ready for connections.
root-db-1  | Version: '10.8.3-MariaDB-1:10.8.3+maria~jammy'  socket: '/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution

# 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@4e9bdc02dd9a:/#

# stop application and also shutdown all containers

[root@dlp ~]#

docker-compose stop

[+] Running 0/0
  Container root-web-1  Stopping 0.1s
  Container root-db-1   Stopping 0.1s
[+] Running 1/2br-f172cf624e51: port 2(vethd5bd225) entered disabled state
  Container root-web-1  Stopped 0.2ss promiscuous mode
  Container root-db-1   Stopping 0.3s(vethd5bd225) entered disabled state
[+] Running 2/2br-f172cf624e51: port 1(veth34f9937) entered disabled state
  Container root-web-1  Stopped 0.2st promiscuous mode
  Container root-db-1   Stopped 0.4ss(veth34f9937) entered disabled state

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

[root@dlp ~]#

docker-compose up -d web

[+] Running 0/1
  Container root-web-1  Starting 0.3s
[+] Running 1/1br-f172cf624e51: port 1(veth2985af3) entered blocking state
  Container root-web-1  Started 0.4ss(veth2985af3) entered forwarding state

[root@dlp ~]#

docker-compose ps

NAME                COMMAND                  SERVICE             STATUS              PORTS
root-db-1           "docker-entrypoint.s…"   db                  exited (0)
root-web-1          "/usr/sbin/nginx -g …"   web                 running             0.0.0.0:80->80/tcp, :::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 Yes
[+] Running 1/0ve root-db-1 (y/N) y
  Container root-db-1  Removed 0.0s

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