This document summarizes a presentation about designing a Docker stack for Symfony applications. It discusses getting started with Docker and some of the challenges that arise when using it in more complex situations. It then introduces Docker Compose as a way to define and run multiple linked containers together more easily. The rest of the document demonstrates a Docker stack created for Symfony apps, explaining how it works to provide a development environment that replicates production and allows for running multiple projects and environments simultaneously in a simple way. It concludes with a demonstration of the Docker stack in action.

1. It’s all about eXperience
Gaetano Giunta
Symfony Live
Sept 2016
Designing a Docker Stack
for Symfony apps:
lessons learned

2. If you have never heard of used
Docker
A.I am living under a rock
B.I am living on the moon
01

3. What is it,inone phrase
Definition according to Me™
"just like a VM, but lighter"

4. Getting started iseasy
Getting off the hook on the other hand…
"just like a VM, but lighter"
all it takes to get started:
docker run -ti ubuntu:15.10 bash

5. Where the magic stops
• how to share application data with the container?
• how to access the apps in the container (map container ports to the
host)?
• how to start multiple containers together and connect them?
• how to access the log files from the application?

6. Then things get tricky
• mapping of user ids to properly handle filesystem permissions
• linking containers when there are circular dependencies (solved with recent
Docker versions)
• applying security updates to existing containers
• and more…
• for some more of the fine details, see f.e. this blog post:
http://blog.kaliop.com/en/blog/2015/05/27/docker-in-real-life-the-tricky-parts/

7. Docker Compose tothe rescue!
• a single file describes multiple containers
• a single command to start/stop them all together
• permits further automation (via eg. introduction of variables)

8. A Docker stack for Symfony apps
A.Source code?
B.https://github.com/kaliop-uk/websummercamp2016
02

9. Introducing the stack
• apache
• mysql
• memcached
• solr
• php cli
• varnish
• nginx
plus
• control panels for all of the above
• phpmyadmin
• maildev (an smtp server for development purposes)
• dockerui (a container monitoring the whole container stack [Inception!])

10. In1000 words
Ascii art rocks!

11. How it works
All the things someone else has figured out for you
• configuration of the applications is mounted as volume, not copied into the
image
a simple service restart is sufficient to take changes into account
• application source code is kept on the host computer
no risk of losing changes when rebuilding containers
no need to have containers running GUI or IDEs
• all log files accessible from the host, in one place
• use ssh-agent to avoid developers storing their own private keys inside the
containers

12. How it works, II
All the things someone else has figured out for you
• allow developers to change some variables, while providing good defaults
• a configuration file is provided, which has all the variables that developers can customize
• a 2nd configuration file has to be created with local changes (empty is fine)
• ex: id of the user account on the host computer, or github credentials
• the config file with local changes is not committed to git
• not tied to a specific project
can be quickly converted for usage of Drupal / eZPublish / etc…
• two of them can be run in parallel

13. How it works, III
All the things someone else has figured out for you
• the containers have to replicate as much as possible a production
environment
the base images used are Debian or Ubuntu (the platforms we
generally deploy on)
• the applications are started using service start and service stop commands
• cronjob tasks definitions are kept as part of the sources of the stack
• developers can access 2 Symfony environments using one stack
• one via http (ie. DEV), one via https + Varnish (ie. UAT)

14. Demo time
At last!

15. I’ll be here all night
THANK YOU
https://github.com/kaliop-uk/websummercamp2016
• @gggeek
• www.kaliop.co.uk