I need 3rd party packages that I would normally get from an "apt install" command. I'm not sure how to handle this in Pants. All of the libraries we used so far are python. Thanks

What have you tried so far? And what kind of packages?

Nothing yet. I'm not sure where to start. The package I'm trying to install now is ros-foxy-ros-base.

I've never used ROS before, so I don't really know whether those are pip installable packages, a dev environment, a system dep, etc?

They are not pip installable. It should be the same for all apt install packages - right?

As far as I know, there is no hermetic ROS plugin at the moment (e.g. Pants would pull down the appropriate ROS binaries, and use them on a per-repo basis). I'm presuming those are dependencies though, akin to having a compiler or other tooling installed on your machine? If they were something sitting in your requirements.txt like other python packages, then Pants could pull them down, wrap them into a pex, and off you go

I've used ROS before but it's been a long time and before I was using Pants. I currently use ffmpeg though and I would imagine a similar circumstance. Ffmpeg has python bindings and there are binaries that we just need to make sure exist before runtime

Yeah, my gut feel is that something would need to already be installed on the machine, and then using system_binaries to make a custom plugin, or using adhoc_tool as a placeholder to pull everything into the pants world https://www.pantsbuild.org/2.18/docs/ad-hoc-tools/integrating-new-tools-without-plugins https://www.pantsbuild.org/2.18/reference/targets/adhoc_tool

it all depends on what you are trying to achieve. IIUC, you are in situation when some of your Python dependencies are provided by system packages, e.g. by installing

apt install python3-apt

you'll be able to do

import apt

in your Python code that has access to the system

site-packages

. If you only want Pants to understand the imports in your code and not throw an

UnownedDependencyError: Pants cannot infer owners for the following imports in the target

when it finds

import apt

, then you could either ignore it with

pants: no-infer-dep

pragma or abuse the default

python_requirement

target:

python_requirement(
    name="python-requirement",
    modules=[
        "apt",
    ],
    requirements=[
        "python3-apt",
    ],
    tags=[
        "debian-package",
    ],
)

this will let Pants link the

import apt

to this package so you can reason about it. However, you won't be able to install those packages which is necessary if you'd like to do

pants run

or

pants test

. This is because Pants won't be able to install a system dependency into a sandbox where a goal process is running. If that's what you want, then you would need to extend Pants to provide support for Debian packages to be used as Python requirements so they are treated in the same way a Python requirement distributed via a Python wheel would. One way to achieve this would be to instruct Pants to bring system packages along when creating a virtual environment in a sandbox, so that all the Debian packages present in the runtime environment would be available in the sandbox virtual environment as well. Even though Pants is all about hermetic environments and having resources external to this hermetic sandbox would violate its principles, one can decide not to attempt to reproduce an "isolated" virtual environment and instead extend Pants to run tests with access to all (or some) system resources accessible on

PATH

.

Thanks all for your replies

you cannot generate a lockfile with this input - there's no

python3-apt

PyPI package which is what Pants telling you in

ERROR: Could not find a version that satisfies the requirement python3-apt (from versions: none)
ERROR: No matching distribution found for python3-apt

@fresh-cat-90827 Could you please direct me to the relevant docs or explain the process to tell pants to defer dependencies?