canonicalwebteam/python3 repository overview

⁠canonicalwebteam/python3 docker image

A Docker image for running Python3 projects in local development. The image will detect and install dependencies automatically.

⁠Project format

This image is meant for running Python3 projects whichkeep their required dependencies in ./requirements.txt.

⁠Usage

The image will install any requirements from ./requirements.txt, or update dependencies if they've changed since last run, and then run the provided commands.

⁠Basic usage

For the most basic usage, where app.py is the Python3 application you want to run:

docker run --tty --interactive --volume `pwd`:`pwd` --workdir `pwd` canonicalwebteam/python3 app.py

This will mount your application directory inside the container, install requirements from ./requirements.txt, and then run app.py.

⁠Saving dependencies

The above command works but will install requirements from scratch every time it's run. To avoid this, create a named data volume for the installed python packages like so:

$ docker run -ti \
         --volume `pwd`:`pwd`  \
         --workdir `pwd`  \
         --volume dependencies:/usr/local/lib/python3.6/site-packages  \
         --publish 8000:8000  \
         canonicalwebteam/python3 app.py

The first time you run the above command it will save the python packages into the a data volume called dependencies. On subsequent runs it will load the same data volume, and only re-install requirements if the requirements directory has been updated.

⁠Changing the path to your requirements file

You can use the REQUIREMENTS_PATH environment variable to specify a different location for requirements.txt. E.g., to run an app with a requirements file at dev-requirements.txt:

docker run -ti  \
       --env REQUIREMENTS_PATH=dev-requiremnts.txt  \
       --volume `pwd`:`pwd`  \
       --workdir `pwd`  \
       --volume dependencies:/usr/local/lib/python3.6/site-packages  \
       --publish 8000:8000  \
       canonicalwebteam/python3 app.py

⁠Waiting for databases

Sometimes this image may be used in conjunction with a database image. In those scenarios, it's often necessary to ensure the application doesn't try to start until the database image is available. canonicalwebteam/python3 contains two helper scripts, /wait-for-postgres and /wait-for-monogo to help in these situations. E.g.:

$ docker run -ti -v `pwd`:`pwd` -w `pwd` canonicalwebteam/python3 /wait-for-postgres postgresql.host 6001
- Trying to connect to postgresql.host:6001 after 0 seconds
- Trying to connect to postgresql.host:6001 after 1 seconds
- Trying to connect to postgresql.host:6001 after 2 seconds
- Trying to connect to postgresql.host:6001 after 3 seconds
- Database available
$ docker run -ti -v `pwd`:`pwd` -w `pwd` canonicalwebteam/python3 app.py