aiohttp web service parent container

This is a parent container to build aiohttp/gunicorn based web services from.

About

The usual docker reasoning is to provide one process per container, however this one breaks from that to provide nginx and gunicorn in one service to serve as a logical unit instead of breaking them up into separate containers.

The reasoning here is if the web service provides static files as well as generated code, the files aren't oddly broken up into multiple containers that will be more difficult to orchestrate. This also allows terminating SSL at the nginx process before passing it to nginx.

However, despite nginx and a supervisord setup being provided here, you are not required to use them if this is only to be an API server that sits behind a container that handles proxying. Simply remove nginx and the supervisord setup for it in a child script.

Provides

• nginx
• supervisord + nginx configuration
• python3.6
• venv (at /var/www/venv/)
• aiohttp, gunicorn and uvloop in the venv

Setup Process

This container by itself provisions very little, just what's listed in the provides section. However, there are a variety of ONBUILD hooks provided.

ARG and ENV

• DEV build arg flag. This is used to mark a container as a development container, this is passed into the environment as the DEV envvar so child containers can use it switch on if needed. By default it is set to 0 which means not a development build. Setting this to 1 triggers the development build hooks in the container.
• The PYTHONASYNCIODEBUG envvar is set by default to the value of $DEV but can be overridden if you do not want asyncio debugging in a development build.
• PYTHONDONTWRITEBYTECODE is set by default to 1, which is my personal preferences leaking in here. Override this if you like having *.pyc and __pycache__ generated.

Provisioning

Here is the order and filepaths executed during child container provisioning:

1. COPY ./container/files into / -- this is used to set any configuration files such as nginx and supervisord
2. COPY . into /app -- this is the base working directory for the image
3. If it exists, source /app/bin/setup.sh
4. Ensure the working directory is /app this is important for the last step
5. Install /app/requirements.txt into the venv -- this file must exist
6. If this is a dev container AND it exists, install /app/requirements-dev.txt into the venv
7. If /app/setup.py exists, install it with the -e and --no-deps flags
8. If it exists, source /app/bin/cleanup.sh

After that, the entrypoint is set to /app/bin/entrypoint.sh and the default command is set to python

The ENTRYPOINT instruction does not need to be overridden if your intention is to just provide a entrypoint commands. If you want to inherit this container's entrypoint, override this and invoke /app/bin/entrypoint.sh from your entrypoint. By default, the entrypoint will exec /var/www/venv/bin/python $@ if the entrypoint command is python otherwise the provided command is exec "$@"