Compatibility with Alpine Linux

[RReverser]

Thanks for proposing a new feature!

Motivation

Many tiny Docker deployments use Alpine Linux as its base to reduce size of images and containers. Currently, wasmer is incompatible with such environments because it's compiled against glibc.

Proposed solution

Provide a build of wasmer that can work with musl libc as well.

Additional context

For background, initially I stumbled upon this due to non-sensical error after installation:

/ # ls /root/.wasmer/bin/wasmer
/root/.wasmer/bin/wasmer
/ # /root/.wasmer/bin/wasmer
sh: /root/.wasmer/bin/wasmer: not found

After searching around, I found explanation of a similar issue as well a workaround that creates a symbolic link for musl libc pretending to be full one: https://stackoverflow.com/questions/34729748/installed-go-binary-not-found-in-path-on-alpine-linux-docker

That helped a bit, but there are still missing functions due to differences in libc implementations:

/ # mkdir /lib64
/ # ln -s /lib/libc.musl-x86_64.so.1 /lib64/ld-linux-x86-64.so.2
/ # /root/.wasmer/bin/wasmer
Error relocating /root/.wasmer/bin/wasmer: __snprintf_chk: symbol not found
Error relocating /root/.wasmer/bin/wasmer: mallinfo: symbol not found
Error relocating /root/.wasmer/bin/wasmer: __fprintf_chk: symbol not found
Error relocating /root/.wasmer/bin/wasmer: __vsnprintf_chk: symbol not found
Error relocating /root/.wasmer/bin/wasmer: __longjmp_chk: symbol not found

Hence, I think it would be best if wasmer would be built against musl as well.

[syrusakbary]

Thanks for creating the issue @RReverser!

It seems the not-found symbols are all related to the emscripten integration. Perhaps we can shape it so we don't require those or adapt them to be compatible with musl.
We could also create a new binary that is built without emscripten support (probably the simplest solution).

Would the latter suffice for your use case?

[RReverser]

Yeah that sounds reasonable.

[krasin]

Just saw an announce of Wasmer 1.0 (congrats!) and tried it locally on an Alpine Linux dev laptop. Did not work, same reasons:

$ ldd ~/.wasmer/bin/wasmer 
	/lib64/ld-linux-x86-64.so.2 (0x7fc4e2942000)
	libdl.so.2 => /lib64/ld-linux-x86-64.so.2 (0x7fc4e2942000)
	librt.so.1 => /lib64/ld-linux-x86-64.so.2 (0x7fc4e2942000)
	libpthread.so.0 => /lib64/ld-linux-x86-64.so.2 (0x7fc4e2942000)
	libm.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7fc4e2942000)
	libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x7fc4de7f6000)
	libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x7fc4de7dc000)
	libc.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7fc4e2942000)
Error loading shared library ld-linux-x86-64.so.2: No such file or directory (needed by /home/krasin/.wasmer/bin/wasmer)
Error relocating /home/krasin/.wasmer/bin/wasmer: __snprintf_chk: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: mallinfo: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __memcpy_chk: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: backtrace_symbols_fd: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: backtrace: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: pthread_getname_np: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __vsnprintf_chk: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __longjmp_chk: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __register_atfork: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __realpath_chk: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __sprintf_chk: symbol not found
Error relocating /home/krasin/.wasmer/bin/wasmer: __res_init: symbol not found

[syrusakbary]

Sorry, this issue completely slipped for 1.0.0.

@jubianchi can we disable emscripten when doing the musl build?

[jubianchi]

I'll have a look at this today.

[jubianchi]

@krasin some update here: I had Wasmer build on musl working.

I'll continue working on that and see how we can produces this builds in our CI pipeline.

[krasin]

@jubianchi awesome, thank you for the update!