Docker Compose · CapRover - EU-Vietnam Business Network (EVBN)

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What is Docker Compose?

For Docker newbies, lots of examples that you find on the internet are Docker Compose. For example, this is a simple Docker Compose for WordPress:

version:
 '3.3'

services:
   db:
     image:
 mysql:5.7
     volumes:
       -
 db-data:/var/lib/mysql
     restart:
 always
     environment:
       MYSQL_ROOT_PASSWORD:
 somewordpress
       MYSQL_DATABASE:
 wordpress
       MYSQL_USER:
 wordpress
       MYSQL_PASSWORD:
 wordpress

   wordpress:
     depends_on:
       -
 db
     image:
 wordpress:latest
     ports:
       -
 "8000:80"
     restart:
 always
     environment:
       WORDPRESS_DB_HOST:
 db:3306
       WORDPRESS_DB_USER:
 wordpress
       WORDPRESS_DB_PASSWORD:
 wordpress
       WORDPRESS_DB_NAME:
 wordpress
volumes:
    db-data:
 {}

It is pretty self-explanatory. It defines one or multiple services (apps) and their configurations such as persistent volumes, mapped ports, environment variable and etc. Docker compose is a really easy and readable way to define a set of apps that need to be working together. Usually to run a docker compose file, you need to run something like:

docker-compose -f my-docker-compose.yml up

Relationship to CapRover – Bad

CapRover is just a thin layer around Docker. It uses docker to build and run your applications. It does all of these through Docker API.

Although Docker Compose a feature in Docker CLI, it is NOT available in Docker API. This means CapRover cannot handle docker compose files.

Relationship to CapRover – Good

Having said that, CapRover has a built in system to parse out docker-compose (partially) and converts it to pieces that Docker API understands. In fact, this is exactly how CapRover one click apps work. One click apps, are just templatized variant of Docker Compose files. For example, this is the one click app for wordpress:

captainVersion:
 4
services:
    $$cap_appname-db:
        image:
 $$cap_db_type:$$cap_database_version
        volumes:
            -
 $$cap_appname-db-data:/var/lib/mysql
        restart:
 always
        environment:
            MYSQL_ROOT_PASSWORD:
 $$cap_db_pass
            MYSQL_DATABASE:
 wordpress
            MYSQL_USER:
 $$cap_db_user
            MYSQL_PASSWORD:
 $$cap_db_pass
        caproverExtra:
            notExposeAsWebApp:
 'true'
    $$cap_appname-wordpress:
        depends_on:
            -
 $$cap_appname-db
        image:
 wordpress:$$cap_wp_version
        volumes:
            -
 $$cap_appname-wp-data:/var/www/html
        restart:
 always
        environment:
            WORDPRESS_DB_HOST:
 srv-captain--$$cap_appname-db:3306
            WORDPRESS_DB_USER:
 $$cap_db_user
            WORDPRESS_DB_PASSWORD:
 $$cap_db_pass
caproverOneClickApp:
    variables:
        -
 id:
 $$cap_db_user
          label:
 Database
 user
          defaultValue:
 wordpressuser
          validRegex:
 /^([a-zA-Z0-9])+$/
        -
 id:
 $$cap_db_pass
          label:
 Database
 password
          description:
 ''
          validRegex:
 /.{1,}/
        -
 id:
 $$cap_wp_version
          label:
 WordPress
 Version
          defaultValue:
 '4.9'
          description:
 Check
 out
 their
 Docker
 page
 for
 the
 valid
 tags
 https://hub.docker.com/r/library/wordpress/tags/
          validRegex:
 /^([^\s^\/])+$/
        -
 id:
 $$cap_db_type
          label:
 Database
 Type
          defaultValue:
 mysql
          description:
 You
 can
 either
 choose
 mariadb
 or
 mysql,
 you
 need
 to
 change
 the
 version
 according
 to
 which
 DB
 is
 selected.
 It
 is
 case
 sensitive.
          validRegex:
 /^(mysql|mariadb)$/
        -
 id:
 $$cap_database_version
          label:
 Database
 Version,
 default
 is
 MySQL
          defaultValue:
 '5.7'
          description:
 Check
 out
 the
 Docker
 pages
 for
 the
 valid
 tags
 https://hub.docker.com/r/library/mysql/tags/
 or
 https://hub.docker.com/_/mariadb?tab=tags
          validRegex:
 /^([^\s^\/])+$/
    instructions:
        start:
 >-
            WordPress is an online, open source website creation tool written in PHP. But in non-geek speak, it’s probably the easiest and most powerful blogging and website content management system (or CMS) in existence today.
             Enter your WordPress Configuration parameters and click on next. A MySQL (database) and a WordPress container will be created for you.  The process will take about a minute for the process to finish.
        end:
 >
            WordPress is deployed and available as $$cap_appname-wordpress . 
             IMPORTANT: It will take up to 2 minutes for WordPress to be ready. Before that, you might see a 502 error page.
    displayName:
 WordPress
    isOfficial:
 true
    description:
 WordPress
 is
 a
 content
 management
 system
 based
 on
 PHP
 and
 MySQL
 that
 is
 usually
 used
 with
 the
 MySQL
 or
 MariaDB
 database
    documentation:
 Taken
 from
 https://docs.docker.com/compose/wordpress/.
 Port
 mapping
 removed
 from
 WP
 as
 it
 is
 no
 longer
 needed

As you can see, the top part is very similar a Docker Compose!

How to Run Docker Compose on CapRover

Note that, as mentioned above, the built-in parser does not support all fields that are available in docker compose. Specifically, it only supports: image, environment, ports, volumes, depends_on, and hostname, other parameters are currently being ignored by CapRover.

Assuming that your Docker Compose doesn’t have any of these parameters, or they are not crucial for your application, you can simply run Docker Compose by

Navigate to Apps
Click on “One Click Apps/Databases”
Navigate to the very bottom of the list, and click on the last item, called >> TEMPLATE <<
Copy the following section to the box:

captainVersion:
 4
caproverOneClickApp:
    instructions:
        start:
 Just
 a
 plain
 Docker
 Compose.
        end:
 Docker
 Compose
 is
 deployed.

After ########, copy the entire content of your Docker Compose. Keep in mind that your services will get prefixed with srv-captain-- when deployed via CapRover. Hence make changes if needed. For example, the complete wordpress docker compose will look like this in CapRover

captainVersion:
 4
caproverOneClickApp:
    instructions:
        start:
 Just
 a
 plain
 Docker
 Compose.
        end:
 Docker
 Compose
 is
 deployed.
 
version:
 '3.3'

services:
   db:
     image:
 mysql:5.7
     volumes:
       -
 db-data:/var/lib/mysql
     restart:
 always
     environment:
       MYSQL_ROOT_PASSWORD:
 somewordpress
       MYSQL_DATABASE:
 wordpress
       MYSQL_USER:
 wordpress
       MYSQL_PASSWORD:
 wordpress

   wordpress:
     depends_on:
       -
 db
     image:
 wordpress:latest
     ports:
       -
 "8000:80"
     restart:
 always
     environment:
       WORDPRESS_DB_HOST:
 srv-captain--db:3306  
       WORDPRESS_DB_USER:
 wordpress
       WORDPRESS_DB_PASSWORD:
 wordpress
       WORDPRESS_DB_NAME:
 wordpress
volumes:
    db-data:
 {}

Alternative Approach

If you can’t make it work with a one click app template, there is another option! You can simply run pure docker compose by download the compose file and run docker compose up. But before that just add captain-overlay-network to your web application section of your docker compose yaml file:

  web-app:
    image:
 .....
    container_name:
 ......
    networks:
      -
 captain-overlay-network

networks:
  captain-overlay-network:
    external:
 true

Now instead of potential port mapping that you might have, like 8080:80, you can just create a CapRover “Nginx Reverse Proxy” app and use your container name as the upstream proxy, like http://web-app and done!