[ptx]

It should be the same process, except that the constraints file is not automatically created or detected, so step 5 would be "pip freeze >constraints.txt" and step 6 would be "pip install -r requirements.txt -c constraints.txt".

The top level dependencies go in requirements.txt and trigger installation of those packages. Everything else goes in the constraints file, which constrains the version that will be installed if something triggers an installation of the package, but it doesn't by itself trigger the installation - it only locks/constrains the versions.

[nickjj]

Wouldn't you also need to run a pip3 install -r requirements.txt before the pip freeze?

Otherwise pip freeze won't find any dependencies.

So you end up having to run something like this:

    pip3 install -r requirements.txt
    pip3 freeze > requirements-lock.txt
    pip3 install -r requirements.txt -c requirements-lock.txt

Mainly because you can't run pip3 install -c requirements-lock.txt on its own it seems. It requires the -r flag.

That is a lot more inconvenient than running `bundle install` and if you use Docker it gets a lot more tricky because a new lock file would get generated on every build which kind of defeats the purpose of it, because ideally you'd want to use the existing lock file in version control, not generate a new one every time you build your image.