Import SQL file into Docker Compose Container

How to import a .sql dump file into a docker container created by docker-compose.

Get in there!

It took me a while to figure out how to properly import a .sql dump file into a docker container I had started with docker-compose. The recommended way was to import the data on creation of the container by adding the dump file to the /docker-entrypoint-initdb.d directory. I wanted to avoid this if possible because the dump file is a backup of a production database but the docker-compose file is shared ...