Change Dockerfile to create smaller image

[izderadicka]

Current Dockerfile creates image with size over 2GB. It's just too much!

Try to come with something smaller - using Ubuntu as base is not efficient, majority of things is just not needed.
audioserve compiles to one binary plus two additional files are needed (index.html and bundle.js for web client).
audioserve depends on few dynamic libraries:

ldd /opt/audioserve/audioserve
	linux-vdso.so.1 =>  (0x00007ffdd6df4000)
	libssl.so.1.0.0 => /lib/x86_64-linux-gnu/libssl.so.1.0.0 (0x00007f848886f000)
	libcrypto.so.1.0.0 => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0 (0x00007f8488492000)
	libtag_c.so.0 => /usr/local/lib/libtag_c.so.0 (0x00007f8488289000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8488085000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8487e7d000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8487c5f000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f8487a49000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8487680000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f8489219000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f848737a000)
	libtag.so.1 => /usr/local/lib/libtag.so.1 (0x00007f8486fc9000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f8486cc5000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f8486aac000)

Try complely static build with musl libc? Then it can use alpine linux?

[izderadicka]

I've tried static build for now I'm sucked with problem to statically linked taglib with rust code - see the issue here emk/rust-musl-builder#65. If anybody has some ideas please help.

[izderadicka]

Current Dockerfile creates image with size over 2GB.

Just to mention that current multistage Dockerfile helped significantly - so it's now ~ 200MB (with 60MB static ffmpeg executable). I'm keeping this opened as there are still possible improvements.

Especially interesting could be a statically linked executable. But there I got stuck, as noted above - static linking with C++ libraries looks like a problem in Rust.

[izderadicka]

Closing because current Docker image is now OKish, further improvement will require static compilation, for which I created separate issue #8