How to name a volume using a docker-compose.yml file? - docker

Question

I'm new to Docker and I'm trying to find out how to set the name of the created data volume. Currently the directory is automatically named as a long hash under /var/libs/docker which is far from user friendly.
I'm attempting to set up a development environment for MODX as shown here:
https://github.com/modxcms/docker-modx
Currently my docker-compose.yml file is as follows:
web:
image: modx
links:
- db:mysql
ports:
- 80:80
db:
image: mysql
environment:
MYSQL_ROOT_PASSWORD: example
ports:
- 3306:3306
command: mysqld --sql-mode=NO_ENGINE_SUBSTITUTION
myadmin:
image: phpmyadmin/phpmyadmin
links:
- db:db
ports:
- 8080:8080
This works perfectly but I'm unsure as to how to name the data volume that I would edit directly with my IDE.
(As a side question, does it have to be created under /var/libs/docker ? Or is there a way of setting it to a directory in my home folder?)
Update:
Thanks to the help from #juliano I've updated my docker-compose.yml file to:
version: '2'
services:
web:
image: modx
volumes:
- html:/home/muzzstick/dev/modxdev
links:
- db:mysql
ports:
- 80:80
db:
image: mysql
environment:
MYSQL_ROOT_PASSWORD: example
ports:
- 3306:3306
command: mysqld --sql-mode=NO_ENGINE_SUBSTITUTION
myadmin:
image: phpmyadmin/phpmyadmin
links:
- db:db
ports:
- 8080:8080
volumes:
html:
external: false
Unfortunately this seems to stop the web container from running.
db and myadmin containers show they're running ok.
There weren't any errors... if I type docker start docker_web_1 it appears to start but docker ps -a shows it exited as soon as it started.
Update 2
Running docker-compose up -d appears to run without issue. But then as you can see below, the web container exits as soon as it's created.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a1dd6d8ac94e modx "/entrypoint.sh apach" 10 seconds ago Exited (1) 5 seconds ago docker_web_1
ee812ae858dc phpmyadmin/phpmyadmin "/run.sh phpmyadmin" 10 seconds ago Up 5 seconds 80/tcp, 0.0.0.0:8080->8080/tcp docker_myadmin_1
db496134e0cf mysql "docker-entrypoint.sh" 11 seconds ago Up 10 seconds 0.0.0.0:3306->3306/tcp docker_db_1
Update 3
OK the error logs for this container shows:
error: missing MODX_DB_HOST and MYSQL_PORT_3306_TCP environment variables
Did you forget to --link some_mysql_container:mysql or set an external db
with -e MODX_DB_HOST=hostname:port?
This error appears to be originating from https://github.com/modxcms/docker-modx/blob/master/apache/docker-entrypoint.sh#L15-L20
Could it be something like linking is handled differently in docker-compose version 2?

Answer 1

To create a named data volume using the version 2 of compose files you will have a separated area:
version: '2'
services:
db:
image: postgres
volumes:
- amazingvolume:/var/lib/postgresql/data
volumes:
amazingvolume:
external: true
So you can define the volume name (amazingvolume), if it's external or not and under your service (db in this example) you can define which directory you gonna mount.

Answer 2

Just search in the docker documentation for hosted mounted volumes:
version: '2'
services:
web:
image: modx
environment:
- MYSQL_PORT_3306_TCP=3306
- MODX_DB_HOST=mysql:3306
volumes:
- /home/muzzstick/dev/modxdev/html:/var/www/html
links:
- db:mysql
ports:
- 80:80
db:
image: mysql
environment:
MYSQL_ROOT_PASSWORD: example
ports:
- 3306:3306
command: mysqld --sql-mode=NO_ENGINE_SUBSTITUTION
myadmin:
image: phpmyadmin/phpmyadmin
links:
- db:db
ports:
- 8080:8080
Change /var/www/html to the directory where the html files will be inside the container. And also create the directory at the left in your host and give read permission to all users.
Regards