使用Docker容器设置开发环境时如何管理开发任务？

Question

I have been researching docker and understand almost everything I have read so far. I have built a few images, linked containers together, mounted volumes, and even got a sample django app running.

The one thing I can not wrap my head around is setting up a development environment. The whole point of docker is to be able to take your environment anywhere so that everything you do is portable and consistent. If I am running a django app in production being served by gunicorn for example, I need to restart the server in order for my code changes to take affect; this is not ideal when you are working on your project in your local laptop environment. If I make a change to my models or views I don't want to have to attach to the container, stop gunicorn, and then restart it every time I make a code change.

I am also not sure how I would run management commands. python manage.py syncdb would require me to get inside of the container and run commands. I also use south to manage data and schema migrations python manage.py migrate . How are others dealing with this issue?

Debugging is another issue. Would I have to somehow get all my logs to save somewhere so I can look at things? I usually just look at the django development server's output to see errors and prints.

It seems that I would have to make a special dev-environment container that had a bunch of workarounds; that seems like it completely defeats the purpose of the tool in the first place though. Any suggestions?

Update after doing more research:

Thanks for the responses. They set me on the right path.

I ended up discovering fig http://www.fig.sh/ It let's you orchestrate the linking and mounting of volumes, you can run commands. fig run container_name python manage.py syncdb . It seems pretty nice and I have been able to set up my dev environment using it.

Made a diagram of how I set it up using vagrant https://www.vagrantup.com/ .

I just run

fig up

in the same directory as my fig.yml file and it does everything needed to link the containers and start the server. I am just running the development server when working on my mac so that it restarts when I change python code.

Answer 1

At my current gig we setup a bash script called django_admin. You run it like so:

django_admin <management command>

Example:

django_admin syncdb

The script looks something like this:

docker run -it --rm  \
-e PYTHONPATH=/var/local \
-e DJANGO_ENVIRON=LOCAL \
-e LC_ALL=en_US.UTF-8 \
-e LANG=en_US.UTF-8 \
-v /src/www/run:/var/log \
-v /src/www:/var/local \
--link mysql:db \
localhost:5000/www:dev /var/local/config/local/django-admin $@

I'm guessing you could also hook something up like this to manage.py

Answer 2

I normally wrap my actual CMD in a script that launches a bash shell. Take a look at Docker-Jetty container as an example. The final two lines in the script are:

/opt/jetty/bin/jetty.sh restart
bash

This will start jetty and then open a shell.

Now I can use the following command to enter a shell inside the container and run any commands or look at logs. Once I am done I can use Ctrl-p + Ctrl-q to detach from the container.

docker attach CONTAINER_NAME