snapcraft should setup search paths/flags for parts built after parts

[Andreas Pokorny]

When building multiple parts from source that depend on each other in a snapcraft session it would be useful if snapcraft would setup the environment for each part in a way that autotools/pkg-config/cmake can find the build results from 'after:'-parts.

Or instead of setting up search paths it might just build & install in a dedicated chroot environment and build each part in the same environment..

Assume this snapcraft.yaml:

name: nfs-server # the name of the snap
version: 0.1 # the version of the snap
# The vendor for the snap (replace 'Vendor <email address hidden>')
vendor: Andreas Pokorny <email address hidden>
summary: Simple NFS Server
description: Simple NFS Server setup for home server use, with manual user and exports setup
icon: folder-remote-nfs.png
architectures: [armhf]

parts:
    libtirpc:
        plugin: autotools
        source: git://github.com/APokorny/libtirpc.git
        source-branch: use-snappy-env
        stage-packages:
            - libkrb5-dev
        filesets:
            tir-files:
                - lib/libtirpc.so*
        snap:
            - $tir-files
    rpcbind:
        plugin: autotools
        source: git://git.linux-nfs.org/projects/steved/rpcbind.git
        stage-packages:
            - libwrap0-dev
        after:
            - libtirpc
    nfs-utils:
        plugin: autotools
        source: git://github.com/APokorny/nfs-utils.git
        source-branch: use-snappy-env
        stage-packages:
            - libcomerr2
            - libnfsidmap2
        after:
            - libtirpc

After building libtirpc when building rpcbind configure fails because it cannot find libtirpc. The configure script uses pkg-config here. I assume snapcraft would use PKG_CONFIG_PATH and PKG_CONFIG_SYSROOT_DIR.

...

[Sergio Schvezov (sergiusens)]

Thank for reporting this, since this is supposed to work, I'd like to request an example where it doesn't to add to our harness and fix with.

[Andreas Pokorny (andreas-pokorny)]

Ok I am still nearly done with my nfs path changes. I will try it again. This evening or tomorrow. It being .. building a modified libtirpc, rpcbind and nfs-utils with the remaining deps coming from ubuntu archive..

[Sergio Schvezov (sergiusens)]

OK, PKG_CONFIG_SYSROOT_DIR is setup incorrectly

[Sergio Schvezov (sergiusens)]

After changing PKG_CONFIG_SYSROOT_DIR to the stagedir I now see this:
checking /usr/include/tirpc/netconfig.h usability... no
checking /usr/include/tirpc/netconfig.h presence... no
checking for /usr/include/tirpc/netconfig.h... no
configure: error: libtirpc not found.

Which was there before the change too, it seems PKG_CHECK_MODULES is not following PKG_CONFIG_SYSROOT_DIR. Is that the right assumption?

[Andreas Pokorny (andreas-pokorny)]

That looks like the output from nfs-utils, the third part of that snap. That thing uses handcrafted autoconf ma4 macros to detect libraries. I am going to change that to PKG_CHECK_MODULES.. but there is some more conditional magic that causes other problems. For testing this bug just ignore the third part ..

[Sergio Schvezov (sergiusens)]

Ok, so I changed the `after` in `nfs-utils` to be `rpcbind` instead of `libtirpc` and now get
`configure: error: libsystemd support requested but found

But before that

checking pkg-config is at least version 0.9.0... yes
checking for TIRPC... yes

Thank you for finally pushing me to fix this fundamental problem that I always procrastinated to fix (use stagedir instead of each parts installdir breaking the privacy of the part).

[Andreas Pokorny (andreas-pokorny)]

awesome - so it is meant to work like that!