Multiple best practices applied as below:
- Replace deprecated `MAINTAINER` with `LABEL maintainer`
- Remove additional `apt clean` as it'll be done automatically
- Use `apt-get` instead of `apt` in script, apt does not have a stable
CLI interface, and it's for end-user.
- Put `apt-get install` & apt lists clean up in the same command
- Use `--no-install-recommends` with `apt-get install` to avoid install
additional packages
- Use `--no-cache-dir` with `pip install` to prevent temporary cache
- Use `COPY` instead of `ADD` for files and folders
- Use spaces instead of mixing spaces with tabs to indent
Size change by the refactor, almost 100MB saved:
```
REPOSITORY TAG IMAGE ID CREATED SIZE
maigret after 9e70c65dde32 1 minutes ago 543MB
maigret before a683f2b71751 7 minutes ago 635MB
```
Soxoj