Install for production

Is your feature request related to a problem? Please describe.

Most dependency managers have a --production (or similar) flag to only install for production. A normal install without that flag install all dependencies (production + development).

Looking at https://pdm.fming.dev/usage/dependency/#install-the-packages-pinned-in-lock-file this is confusing.

Describe the solution you’d like

I would like it to mimic how other tools does this and believe this tool incorrectly took the approach of pipenv. See https://github.com/pypa/pipenv/issues/3093#issuecomment-432718562 for more reference of tools (the entire thread is interesting).

The reason is that developers are bound to want to install all (production + dev) dependencies in their daily work. A pdm install is thus quicker to write. It also mimics most (all?) other package managers out there.

[frostming]

In fact, it is likely that I would switch to CalVer at some point 🤣 https://hynek.me/articles/semver-will-not-save-you/

[pawamoy]

command	what it does
1- pdm install	installs prod and dev deps (not optional prod deps)
2- pdm install -s hello	installs prod and dev deps, as well as hello optional prod group
3- pdm install -d	installs prod and dev deps (not optional deps), redundant with °1
4- pdm install -ds hello	installs prod deps and hello group of dev deps
5- pdm install --production	installs only prod deps
6- pdm install --production -s hello	installs prod deps and hello optional prod group
7- pdm install --production -d	does not make sense
8- pdm install --production -ds hello	does not make sense

Seeing these, I feel like if we go for a --production flag, the -d flag should be removed. Sections should have different names between prod groups and dev groups, allowing -s to match prod groups and/or dev groups.

Lets shorten --production to -p in this example. This would give us this:

command	what it does	useful…
1- pdm install	installs prod and dev deps (no prod groups)	locally/in CI
2- pdm install -s prodgroup1	installs prod deps, dev deps, and “prodgroup1” prod group	locally/in CI
3- pdm install -s devgroup1	installs prod deps and only “devgroup1” dev group	in CI
4- pdm install -s prodgroup1 -s devgroup1	installs prod deps, “prodgroup1” prod group and “devgroup1” dev group	in CI
5- pdm install -p	installs only prod deps	in CD
6- pdm install -p -s hello	installs prod deps and “hello” prod group. if “hello” is a dev group, fails	in CD

Additionally there’s the --no-default flag that could be used in the first 4 cases to prevent installing the prod deps (those that are not optional), useful in CI.