docker-compose.yml¶

This is a YAML file defining services, networks, and volumes for multi-container Docker applications. In other words, all the parameters you have used with docker run you could specify in a docker-compose.yml file. Then, with a single command, create and start all the services with your configurations.

In this example, we will launch just one image, but keep in mind that a docker-compose.yml file could specify more than one image at the same time.

Tip

For more information, see the Compose File Version 3 Reference

Move the default docker-compose.yml from shellhttpd.disabled to your folder:

mv ../shellhttpd.disabled/docker-compose.yml .

Read the docker-compose.yml file:

cat docker-compose.yml

docker-compose.yml:

version: '3.2'

services:
  httpd:
    image: hub.foundries.io/<factory>/shellhttpd:latest
    restart: always
    ports:
      - 8080:${PORT-8080}
    environment:
      MSG: "${MSG-Hello world}"

Most of the parameters were already used in the previous commands. The only thing you need to change is the image parameter.

In the next tutorial, you will build and deploy the image with FoundriesFactory and there the image with hub.foundries.io will be necessary.

For now, because you are still developing locally, you need to edit the image parameter to use the image you have built in the previous steps.

Change the image parameter to the name and tag we built locally shellhttpd:1.0:

gedit docker-compose.yml

docker-compose.yml:

version: '3.2'

services:
  httpd:
#    image: hub.foundries.io/<factory>/shellhttpd:latest
    image: shellhttpd:1.0
    restart: always
    ports:
      - 8080:${PORT-8080}
    environment:
      MSG: "${MSG-Hello world}"

Notice that the MSG variable is configured to use Hello world as default.

To run your docker-compose application, execute the docker-compose up --detach command.

docker-compose up --detach

Where:

--detach or -d - Run containers in the background.

To verify the running containers:

docker ps

Example Output:

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
dbc969a5487d        shellhttpd:1.0       "/usr/local/bin/http…"   3 minutes ago       Up 3 minutes        0.0.0.0:8080->8080/tcp   shellhttpd_httpd_1

Test the container with curl:

curl 127.0.0.1:8080

Example Output:

Hello world