Got into a peculiar situation running an operation that uses

Question

Got into a peculiar situation running an operation that uses `chroot`

fresh-cat-90827 · Answer

Reading the docs gt When Pants runs most processes it runs in a chroot temporary directory Usually this gets cleaned up after the Process finishes You can instead run pants no process execution local cleanup which will keep around the folder The plugin I work on building a Debian package is run itself as `chroot` and Pants runs the `Process` under `chroot` as well This causes the `dpkg deb` system utility that builds a Debian package to fail reading the input files By running with ` no process execution local cleanup` I can see that the necessary files have been copied and the ` run sh` contains correct instructions and can be re run in that temp directory producing the expected results However the ` pants package sample debian package no process execution local cleanup` command fails ```stdout dpkg deb building package sample debian package in sample debian package deb stderr dpkg deb subprocess unable to execute tar cf tar No such file or directory dpkg deb error tar cf subprocess returned error exit status 2``` I don t think there was a precedent for this as far as I know none of the Pants internal operations or via plugins deal with `chroot` in the same way that Debian `dpkg deb` utility does I ve researched on `dpkg deb` and how one can configure it with regards to `chroot` but haven t found anything useful Is there a way to experiment running a `Process` not under `chroot` to see if it is indeed the cause of the trouble so that we could think of a workaround

fast-nail-55400 · Answer

does `tar` need to be available in the chroot setup by Pants and is it

fast-nail-55400 · Answer

My thought is whether `dpkg deb subprocess unable to execute tar cf tar No such file or directory` refers to `tar` being missing

fresh-cat-90827 · Answer

gt does tar need to be available in the chroot setup by Pants I wish I knew how to check that slightly smiling face

fresh-cat-90827 · Answer

that is `tar` will be used by `dpkg deb` to create an archive but I am not sure if I have to tell Pants explicitly that I want `tar` executable to be available Isn t it available if it s on the `$PATH`

fast-nail-55400 · Answer

well it can be on the PATH but those directories will be inaccessible from within the chroot

fast-nail-55400 · Answer

this assumes that a chroot is involved

fast-nail-55400 · Answer

so to debug invoke some commands as part of your invocation of `dpkg deb` to display $PATH and whatever else you think relevant

hundreds-father-404 · Answer

Look at archive py there is a type like Tar or TarBinary iirc that uses BinaryPaths to find the preinstalled Tar program For dpkg you ll want to set the Process s `env` so that PATH includes the path to the tar s `first path` I m afk but I think if you grep you ll see how that type gets used

enough-analyst-54434 · Answer

To clarify Pants does not use the `chroot` command We hijack the term and do something much less stringent

fresh-cat-90827 · Answer

< fast nail 55400> thank you < hundreds father 404> I have now ```tar binary path = await find tar print PATH tar binary path path ``` which gives me ```19 01 01 47 INFO stdout PATH usr bin tar 19 01 01 47 INFO stdout n ``` the problem remains ```stderr dpkg deb subprocess unable to execute tar cf tar Not a directory dpkg deb error tar cf subprocess returned error exit status 2``` is passing `env= PATH tar binary path path ` to the `Process ` sufficient to expose the executables on the `$PATH`

fresh-cat-90827 · Answer

oh it works sorry of course it has to be ` PATH usr bin `

fresh-cat-90827 · Answer

I read that `pathlib` should be avoided but would using `Path tar binary path path <http parent as|parent as> posix ` be appropriate here

fresh-cat-90827 · Answer

to get from ` usr bin tar ` to ` usr bin `

hundreds-father-404 · Answer

`Path` should be avoided but you can use `str PurePath tar binary path path parent ` safely gt tar binary path = await find tar Instead of calling that put `TarBinary` in the signature for your new ` rule` which will cause the engine to run the rule `find tar` I m really surprised `await find tar ` worked

fresh-cat-90827 · Answer

amazing I ve got my first Debian package created in the `dist ` smile