Clojurians Log v2

Hey there 🙂 Is anybody here who could help me understand how graalvm and nix interact? I'm trying to build https://github.com/theiceshelf/firn/ from nix and it seems to succeed, but the resulting binary gives me an error when trying to execute it:

Error: Could not find or load main class firn.core
Caused by: java.lang.ClassNotFoundException: firn.core

i'd also gladyly use pre-built binaries, but executing any graalvm bin on nixos aborts with "file does not exist or is not an executable". if somebody knows how to fix that, that would be amazing as well

chmod +x <executable>?

Unfortunately it's not that simple

Meaning that I checked that already and I still get the same message

@arne-clojurians This is probably because the executable you build/use is glibc-linked

The exact error is

Failed to execute process '../firn-test/firn'. Reason:
The file '../firn-test/firn' does not exist or could not be executed.

Try the babashka static binary, it probably works

It is statically linked against musl

The Error: Could not find or load main class firn.core is probably due to dynamic requires or so

The same thing happens with the most recent prebuilt babashka bin

There's a nixpkg I'm using though: https://github.com/NixOS/nixpkgs/blob/3b6c3bee9174dfe56fd0e586449457467abe7116/pkgs/development/interpreters/clojure/babashka.nix

@arne-clojurians The -> static <- pre-built bin?

Ah no, you're right 🙂

https://github.com/babashka/babashka/releases/download/v0.4.6/babashka-0.4.6-linux-amd64-static.tar.gz

Can I see how exactly that's built?

sure, babashka is open source.

Found the install file already

Thanks!

And thanks for babashka of course

For static linking with musl, you also might want to read: https://github.com/lread/clj-graal-docs#static-linking-with-musl

Yes, that's exactly what I was looking for

Ah I see firn is already made to be compatible for graalvm

https://github.com/theiceshelf/firn/blob/master/bin/compile

Yes, exactly. But the provided binary raises the error described above

Which I'm trying to wrap my head around

which one

the executable not found error I already explained: this is because it's linked against glibc

and glibc isn't in a standard location in nixos

but perhaps it would work if you build it locally though, hmm

perhaps @thiagokokada can help you, he also uses nixos

as does @ericdallo

I am trying to understand the exactly problem here? Is babashka static binary also having this issue of "file not found" :thinking_face: ?

BTW, if firn is having this issue it is probably using dynamic link

You can use ldd to check this

the bb static should work.

Graalvm non static binaries doesn't work on NixOS unless you compile the image on your machine

but if you build firn locally in nixos, wouldn't it work with glibc as well?

The bb static works fine for me and @thiagokokada on nixos

BTW

ldd firn
ldd: warning: you do not have execution permission for `./firn'
	linux-vdso.so.1 (0x00007ffe6a9cb000)
	libpthread.so.0 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib/libpthread.so.0 (0x00007f2fb26f4000)
	libdl.so.2 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib/libdl.so.2 (0x00007f2fb26ef000)
	libz.so.1 => not found
	libc.so.6 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib/libc.so.6 (0x00007f2fb252e000)
	/lib64/ld-linux-x86-64.so.2 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib64/ld-linux-x86-64.so.2 (0x00007f2fb63d2000)

> but if you build firn locally in nixos, wouldn't it work with glibc as well? It works as long the PATH to glibc doesn't change (but it changes frequently, for example, if any library that glibc depends is updated, the hash on the path is updated)

so, for graalvm works on nixos I always need to go into a shell with gcc, something like this should work:

nix-shell -p 'gcc'

and then graalvm native-image compile works

this is because the gcc build input is missing from the graalvm nixpkgs derivation

> so, for graalvm works on nixos I always need to go into a shell with gcc, something like this should work: This may work with luck, but it is not necessary correct

Like I said, a rebuild on gcc may broke the binary

Anyway, the root cause of the issue seems to be the fact that firn is not statically compiled

So maybe ask the maintainer if it could be static compiled :thinking_face: ? Or package it on nixpkgs

probably a PR which makes musl the default on linux is the easiest route

there's also this patch program for nixos right

to make it work with the local glibc

Yeah, patchelf

But looking at the ldd, it is actually missing libz

$ ldd firn
ldd: warning: you do not have execution permission for `./firn'
	linux-vdso.so.1 (0x00007ffe6a9cb000)
	libpthread.so.0 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib/libpthread.so.0 (0x00007f2fb26f4000)
	libdl.so.2 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib/libdl.so.2 (0x00007f2fb26ef000)
	libz.so.1 => not found
	libc.so.6 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib/libc.so.6 (0x00007f2fb252e000)
	/lib64/ld-linux-x86-64.so.2 => /nix/store/ikl21vjfq900ccbqg1xasp83kadw6q8y-glibc-2.32-46/lib64/ld-linux-x86-64.so.2 (0x00007f2fb63d2000)

Only libz.so.1 is not found for firn

I found a working nix derivation https://github.com/Emiller88/dotfiles/blob/master/packages/firn.nix

nice

Thanks for helping everyone 🙂 That was very informative

… static compilation with musl would still make the resulting binary significantly smaller, i guess?

with babashka it's only a 5mb difference or so

ah yes, i mean vs using the patchelf'd version

are you talking about dynamically linked babashka vs statically linked against musl?

yes. you can see the binary sizes by going into the #babashka-circleci-buildss channel