Compile / build borgbackup with musl

[noplanman]

Have you checked borgbackup docs, FAQ, and open Github issues?

Yes

Is this a BUG / ISSUE report or a QUESTION?

Question

Describe the question.

Does anybody have experience building borgbackup with musl?

This would be great, to add support for OpenWrt based routers and any other devices that prefer musl instead of glibc.

[ThomasWaldmann]

I never tried...

[noplanman]

I'm asking because of an issue we got on the ARM binary builder repo:
https://git.feneas.org/borg-binary-builder/borg-binaries/-/issues/6

Would be super cool to have binaries for OpenWrt routers! (not only because I have one too 😉)

As this is completely unknown territory for me, it would be great if somebody with experience would chime in and see if they could get it to work 🙏

[Gu1nness]

Seems interesting.
There is a Vagrant VM for OpenWRT for testing, and setting up information

[build]
compiler=musl

in setup.cfg could do the trick to build with it for this specific VM. What do you think @ThomasWaldmann

[ThomasWaldmann]

Don't most OpenWrt based systems have too little RAM for borg anyway?

[noplanman]

@ThomasWaldmann How much RAM does Borg need / recommend?

I have a Turris Omnia with 1GB and there are versions with 2GB RAM, which should be more than enough, right?

@Gu1nness Super cool, that would be great 😃

[ThomasWaldmann]

It depends, there are some formulas on the docs to estimate RAM usage.

[noplanman]

@Gu1nness I've tried your suggestion, but then end up with this error:
error: don't know how to compile C/C++ code on platform 'posix' with 'musl' compiler

I've installed musl-tools (which in turn installs musl and musl-dev).
How can I make python know about the musl compiler? Haven't found anything online 😕

[dblsaiko]

I have no problem using the latest commit (fc92587) of borg with musl on Gentoo x86-64 so far fwiw. Release 1.1.14 and before crashes with this error when trying to run it for me, although that might be fixable on Gentoo's side.

[ThomasWaldmann]

@2xsaiko we do not use libgomp, so not sure why there is an issue with that or whether that has anything to do with borg.

[noplanman]

@2xsaiko Would you mind sharing what you mean exactly? You're able to build borg from source with musl?

If you could share how, I'd hugely appreciate it, thanks 🙏

[dblsaiko]

I didn't do anything special, just installed the app-backup/borgbackup-9999 ebuild (version 9999 ebuilds use the source from the latest git commit by default). I did have to put export BORG_OPENSSL_PREFIX=/usr into /etc/portage/env/app-backup/borgbackup-9999 since it needed that variable set when building. This is on a standard gentoo install using the musl profile and with the musl overlay enabled (which patches a bunch of stuff that would otherwise not compile, although I'm not sure it's relevant here).

Or, the non-gentoo specific version (that I tried to test if the error I mentioned above was a bug on gentoo's side or not), I cloned the repo, made a new virtualenv (python -m venv env, . env/bin/activate) so I didn't have to globally install borg, and then did BORG_OPENSSL_PREFIX=/usr python setup.py install. This also works as expected using the latest commit.

I assume you're trying to cross-compile for musl though instead of directly on the target?

[noplanman]

I assume you're trying to cross-compile for musl though instead of directly on the target?

Exactly. But if a virtual target with the required musl setup can be used as well, that would work. I'm just so lost with this that I really don't know what to be looking for 😕

If there were a docker image I could take that has all musl "stuff" set up, that would be perfect.

[noplanman]

I've tried with a bunch of docker images that I found but my know-how is just too limited. Hope somebody with more experience can find a way to build a binary that works with musl, like for OpenWRT-based routers.

[ThomasWaldmann]

Looks like there is a borg package for alpine linux, so it seems to work with musl:

https://pkgs.alpinelinux.org/package/edge/community/x86_64/borgbackup