CentOS 7
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Docker : Use Docker Compose
2018/08/28
 
Install Docker Compose to create or run multiple Containers easily.
[1] Install Docker Compose.
# install from EPEL

[root@dlp ~]#
yum --enablerepo=epel -y install python2-pip
[root@dlp ~]#
pip install docker-compose
[2] For example, create a config to create 2 containers, one has Apache httpd, one has MariaDB.
# create Dockerfile with httpd

[root@dlp ~]#
vi Dockerfile 
FROM centos
MAINTAINER ServerWorld <admin@srv.world>

RUN yum -y update
RUN yum -y install httpd

EXPOSE 80
CMD ["/usr/sbin/apachectl", "-D", "FOREGROUND"]
# 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: centos
      MYSQL_PASSWORD: password
      MYSQL_DATABASE: centos_db
    ports:
      - "3306:3306"
  web:
    build: .
    ports:
      - "80:80"
    volumes:
      - /var/lib/docker/disk02:/var/www/html
# if SELinux is Enforcing, change to permissive or disabled

[root@dlp ~]#
setenforce 0
# build and run application

[root@dlp ~]#
docker-compose up -d 

Building web
Step 1/6 : FROM centos
Trying to pull repository docker.io/library/centos ...
latest: Pulling from docker.io/library/centos
256b176beaff: Download complete
.....
.....
Creating root_web_1 ...
Creating root_db_1  ...
Creating root_web_1 ... done
Creating root_db_1  ... done
[root@dlp ~]#
docker ps 

CONTAINER ID   IMAGE        COMMAND                  CREATED          STATUS         PORTS                    NAMES
06ece319c627   mariadb      "docker-entrypoint..."   20 seconds ago   Up 18 seconds  0.0.0.0:3306->3306/tcp   root_db_1
1f3796c137f3   root_web     "/usr/sbin/apachec..."   20 seconds ago   Up 18 seconds  0.0.0.0:80->80/tcp       root_web_1
# confirm possible to access or not

[root@dlp ~]#
mysql -h 127.0.0.1 -u root -p -e "show variables like 'hostname';" 

Enter password:
+---------------+--------------+
| Variable_name | Value        |
+---------------+--------------+
| hostname      | 06ece319c627 |
+---------------+--------------+
[root@dlp ~]#
mysql -h 127.0.0.1 -u centos -p -e "show databases;" 

Enter password:
+--------------------+
| Database           |
+--------------------+
| centos_db          |
| information_schema |
+--------------------+
[root@dlp ~]#
echo "Hello Docker Compose World" > /var/lib/docker/disk02/index.html

[root@dlp ~]#
curl localhost

Hello Docker Compose World
[3] The follows are some other basic Operation for Docker Compose.
# show status of application

[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 application

[root@dlp ~]#
docker-compose logs 

Attaching to root_db_1, root_web_1
web_1  | Passing arguments to httpd using apachectl is no longer supported.
web_1  | You can only start/stop/restart httpd using this script.
.....
.....
db_1   | 2018-08-28  2:35:54 0 [Note] Added new Master_info '' to hash table
db_1   | 2018-08-28  2:35:54 0 [Note] mysqld: ready for connections.
db_1   | Version: '10.3.9-MariaDB-1:10.3.9+maria~bionic'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution
# run commands inside a container

# for container name, it's just the name set in [docker-compose.yml]

[root@dlp ~]#
docker-compose exec db /bin/bash 

root@06ece319c627:/#
# stop allications

[root@dlp ~]#
docker-compose stop 

Stopping root_web_1 ... done
Stopping root_db_1  ... done
# run an application particularly

# if it has dependency, another container also runs

[root@dlp ~]#
docker-compose up -d web 

Stopping root_db_1  ...
Stopping root_web_1 ...
Stopping root_db_1  ... done
Stopping 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 ...   Exit 137
# remove applications

# running container won't be removed

[root@dlp ~]#
docker-compose rm 

Going to remove root_db_1, root_web_1
Are you sure? [yN] y
Removing root_db_1 ... done
Removing root_web_1 ... done
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