Updating a Symfony app with Docker-compose without losing data - symfony

Question

I have a multi-container Symfony application that uses docker-compose to handle the relationships between the containers. To simplify a little, i have 4 main services :
code:
image: mycode
web:
image: mynginx
volumes-from:
- code
ports:
- "80:80"
links:
- php-fpm
php-fpm:
image: myphpfpm
volumes-from:
- code
links:
- mongo
mongo:
image: mongo
The "mycode" image contains the code of my application and is built from the following Dockerfile :
FROM composer/composer
RUN apt-get update && apt-get install -y \
libfreetype6-dev \
libmcrypt-dev \
libxml2-dev \
libicu-dev \
libcurl4-openssl-dev \
libssl-dev \
pkg-config
RUN docker-php-ext-install iconv mcrypt mbstring bcmath json ctype iconv posix intl
RUN pecl install mongo \
&& echo extension=mongo.so >> /usr/local/etc/php/conf.d/mongo.ini
COPY . /code
WORKDIR /code
RUN rm -rf /code/app/cache/* \
&& rm -rf /code/app/logs/* \
&& chown -R root /code/app/cache \
&& chown -R root /code/app/logs \
&& chmod -R 777 /code/app/cache \
&& chmod -R 777 /code/app/logs \
&& composer install \
&& rm -f /code/web/app_dev.php \
&& rm -f /code/web/config.php
VOLUME ["/code", "/code/app/logs", "/code/app/cache"]
At first, deploying this application was easy. I just had to do a simple docker-compose up -d and it created all the containers and ran them without any issue. But then i had to deploy a new version.
This configuration uses volumes to store data :
the source code is mounted on the /code volume, and shared between 3
containers (code, web, php-fpm). It has to be replaced by a new version when deploying.
the MongoDb data is on another
volume, mounted only by the mongo container. I have to keep this data between deployments.
When i deploy an update to my code, i publish the new version of the mycode image and re-create the container. But since the /code volume is still used by the web and php-fpm containers, the old volume can't be replaced by the new one. I have to stop all the running services to delete the old volume, and if i use the docker-compose rm -v command, it will delete the mongodb data too !
Can't i replace only one volume with a new version, without any downtime ?
So i'm kind of stuck here. I'm thinking of having a permanent volume to store the code and update it through SSH with Capistrano, old style. This will allow me to run doctrine migrations scripts after deployment too. But i have other issues with it as Capistrano uses symlinks to handle versions so i can't just mount the /current folder to /code.
Do you have a solution to handle the deployment of a Docker application without losing data and without downtime ?
Should i use manual scripts instead of docker-compose ?

Answer 1

the source code is mounted on the /code volume
This is the problem, it is not what you want.
Code never goes into a volume, it should change when the image changes. Volumes are for things that you want to preserve between changes to the image (data, logs, state, etc).
Code is the immutable thing that you want to replace when you change a container. So remove the /code volume from the Dockerfile entirely, and instead do an ADD . /code in the mynginx and myphpfpm Dockerfiles.
With that change, you can deploy with just up -d. It will recreate any container that have changed, and your volumes will be copied over. You don't need an rm anymore.
If you have your Dockerfile for myphpfpm and mynginx in a different directory, you can build using docker build -f path/to/dockerfile .
Using a host volume (as suggested in another answer) is another option, however that's not usually what you want outside of development. With a host volume you would still remove the /code VOLUME from the dockerfile.

Answer 2

Do not copy the code via the Dockerfile, just attach volumes to the 'code' container.
Few edits:
code:
image: mycode
volumes:
- .:/code
- /code
web:
image: mynginx
volumes-from:
- code
ports:
- "80:80"
links:
- php-fpm
php-fpm:
image: myphpfpm
volumes-from:
- code
links:
- mongo
mongo:
image: mongo
Same thing applies to mongo mount it to an external volume so it persists when the container shuts down. Actually there is also another method, they mention it in their dockerhub page https://hub.docker.com/_/mongo/
Where to Store Data
Important note: There are several ways to store data used by
applications that run in Docker containers. We encourage users of the
mongo images to familiarize themselves with the options available,
including:
Let Docker manage the storage of your database data by writing the
database files to disk on the host system using its own internal
volume management. This is the default and is easy and fairly
transparent to the user. The downside is that the files may be hard to
locate for tools and applications that run directly on the host
system, i.e. outside containers.
Create a data directory on the host system (outside the container) and
mount this to a directory visible from inside the container. This
places the database files in a known location on the host system, and
makes it easy for tools and applications on the host system to access
the files. The downside is that the user needs to make sure that the
directory exists, and that e.g. directory permissions and other
security mechanisms on the host system are set up correctly.