The document provides an overview of Docker Compose, a tool for defining and running multi-container Docker applications, showcasing its features, file structure, and usage examples. It details the evolution of Docker Compose from its inception to its current functionalities, highlighting its capability to manage services, volumes, and network configurations within various environments. Additionally, the presentation emphasizes how to execute, clean up, and manage multiple executions of Docker Compose applications without conflicts.

1. Multi container applications
with Docker Compose
ContainerDay 2019 – Bologna, Italy

2. Who am I?
2
Paolo Ferretti
Developer Advocate @MailUpGroup
Twitter: @paoferretti

3. What is Docker Compose?
3
Docker Compose is a tool for defining
and running multi-container Docker
applications.

4. Docker Compose background
First Fig
release
End 2013
Fig release
1.0.0
October
2014
Docker
Compose
release 1.24
Today
Fig joins
Docker
July 2014
Fig renames
to Docker
Compose
November
2014
4

5. 5
~ 17.700GitHub stars
~ 3.000OSS libraries and projects depends on
> 1.400.000Downloads on PyPi last month

6. Docker Compose
6
Simple YAML file to configure
your application’s services.
With a single command, you
create and start all the services
from your configuration.
Docker Compose works in all
environments:
- production
- staging
- development
- testing
- CI workflows
HOW? WHERE?

7. Multiple isolated environments on
a single host
Preserve volume data when
containers are created
Variables and composition
between environments
Only recreate containers that
have changed
7
Docker Compose
main features

8. Version: (mandatory): the first line
at the root of the file
Services: definitions for the
different application services
Volumes: volumes to create for
our services
Networks: networks to create for
our services
8
version: "3"
services:
web:
…
database:
…
networks:
…
volumes:
…
Docker Compose file structure

9. version: "3"
services:
marty:
image: container_day_marty:latest
ports:
- 8080:8080
A first version of our Docker Compose file
9
$ docker-compose -f docker-compose-simple.yml up

11. version: "3"
services:
marty:
image: container_day_marty:latest
ports:
- 8080:8080
A second version of our Docker Compose file
11
emmet:
image: container_day_emmet:latest
ports:
- 8081:8080

13. 13
version: "3"
services:
lorraine:
…
depends_on: [database]
database:
image: postgres:12.0-alpine
volumes:
- ./postgres:/docker-entrypoint-initdb.d
An example with a database

15. 15
version: "3"
services:
lorraine:
image: ...:latest
ports:
- 8080:8080
depends_on: [database]
Let’s compose with Docker Compose
version: "3"
services:
database:
image: postgres:12.0-alpine
volumes:
- ./postgres:/docker-entrypoint-initdb.d
docker-compose-app.yml docker-compose-services.yml
$ docker-compose -f docker-compose-app.yml -f docker-compose-services.yml up

17. 17
version: "3"
services:
database:
ports:
- 5432:5432
Compose for local and containerized execution
version: "3"
services:
database:
image: postgres:12.0-alpine
volumes:
- ...
docker-compose-services.yml
$ docker-compose -f docker-compose-app.yml -f docker-compose-services.yml up
docker-compose-services-local.yml

19. $ docker-compose
-f docker-compose-app.yml
-f docker-compose-services.yml
run lorraine
$ docker-compose
-f docker-compose-app.yml
-f docker-compose-services.yml
down --rmi local --volumes --remove-orphans
Execute, exit and clean up
19

21. Using the environment variable
COMPOSE_PROJECT_NAME
We can run the same compose stack multiple times on the same
machine, without conflicts.
Multiple executions
21

23. Thanks!
@paoferretti
paolo.ferretti@fastmail.com
https://joind.in/talk/4d86a
https://github.com/pferretti/container_day_2019

24. Credits
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◂ Photos created by Freepik - Freepik.com