[Nix-dev] Minimal disk image without gcc?

[Layus]

On 19/04/16 11:52, Wout Mertens wrote:
> Hi,
>
> I would like to make a specialized image that just runs some tools and 
> has nothing else installed.
>
> If I uset the minimal profile it has stdenv, which includes 100MB of gcc.
>
> Pointers?
I am also working on this. From my investigations, the closure-size 
feature has everything required to get rid of gcc.out (and keep gcc.lib 
if required).
However, many packages are not correctly stripped or somehow maintain a 
reference to build inputs like gcc.

To benefit from this feature, you need to build from master.
If your closure still includes some gcc-X.Y.Z (gcc-X.Y.Z-lib is ok), 
here are some hints to track the misbehaving package.


You need to find package depending on gcc, then find why they have 
runtime dependencies on their compiler.

$ nix-store -qR ./result | grep gcc
/nix/store/ikzdbd65z7453spdvm05r0izd56zdvkx-gcc-4.9.3 <- you want to get 
rid of this one.
...

$ blame () {comm -12 <(nix-store -qR "$1" | sort) <(nix-store -q 
--referrers "$2" | sort); }
$ blame ./result /nix/store/ikzdbd65z7453spdvm05r0izd56zdvkx-gcc-4.9.3
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/
... # (All these packages have runtime dependencies on gcc binaries.)

Now you can try to investigate why they do depend on the full gcc.
It is probably an unstripped binary, or a wrong rpath.
Sometimes, the package keeps track of its buld flags, as mongo does for 
its --version info.

$ grep /nix/store/ikzdbd65z7453spdvm05r0izd56zdvkx-gcc-4.9.3 -r 
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3 -al
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/bin/ppdhtml
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/bin/ppdc
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/bin/ppdpo
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/bin/ppdmerge
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/bin/ppdi
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/lib/cups/daemon/cups-driverd
/nix/store/rdp4z92qb7jr082pfl5b7jxwiiv3pic0-cups-2.1.3/lib/libcupsppdc.so.1

Now you can simply fix the derivations of these packages and get rif of gcc.

Layus.