at-spi2-core has a large closure size

[matthewbauer]

Issue description

Looking at at-spi-core2, the closure size looks really big:

$ du -sch $(nix-store -qR /nix/store/dglh318sp4xzybap1mm2mlcy8rv1nkl6-at-spi2-core-2.32.1) | sort -h
16K	/nix/store/y48is3y65apgyjwlwiyzjay1dw19l19a-dns-root-data-2019-01-11
36K	/nix/store/vckbx0p1isjvmgjh7ppni3h87imazbzb-libcap-2.27-lib
44K	/nix/store/jf6lfawjvwr6ggnd4lhc5w4dp9v3kgh4-libXdmcp-1.1.3
56K	/nix/store/z2darh83lb4rmsfnnyjc0hll51fyvj49-libSM-1.2.3
64K	/nix/store/yh1w64xprl0rxmj8nvxpmikp6x3qvgdb-libffi-3.2.1
68K	/nix/store/qbwcp86aslamyhhmf2xx0l5d17dyg2jh-libmnl-1.0.4
80K	/nix/store/v31bag67wm17wkdg7zr9yi62c5028y59-libXau-1.0.9
84K	/nix/store/mmjbmvw64yl2756y1zvsxk0ic0nhzq2a-libnfnetlink-1.0.1
84K	/nix/store/rj8xd9ajm3wqjz1vfkignlp011fss53q-bzip2-1.0.6.0.1-bin
88K	/nix/store/206dvjl6595dk40dli12ziv393ww54wl-bzip2-1.0.6.0.1
92K	/nix/store/cd09qv56inq4gwa89656r4n0lq0vgidw-libXi-1.7.9
100K	/nix/store/5l3967kll8m6s66zprzwb2p6vf2mh5yd-libtasn1-4.13
108K	/nix/store/lswf09qbkkrqd0rgzaqyrkr44lf78y9x-libXext-1.3.4
128K	/nix/store/4qq5hh1r6sqb0kpxc305rb468s45j4aw-libICE-1.0.9
152K	/nix/store/ynykygggqw7l6wy5cp45565c0phxh8kv-zlib-1.2.11
164K	/nix/store/xdhh337yhl93x33vzd9davinrbr9x9iz-libmicrohttpd-0.9.63
184K	/nix/store/dp4npqj13czk7f49q3dy0warx2g68wrh-gzip-1.10
200K	/nix/store/sl5ij4lqwpll3hnl74f8fw797k9imh3x-acl-2.2.53
208K	/nix/store/skj3vdaxmbwzwxg5npdm437y4ka67kl2-attr-2.4.48
220K	/nix/store/zvfhspl24f45ml3jq2a424rngfl2vhnw-libXtst-1.2.3
260K	/nix/store/wccns8l8bav11z3xlhasmnkz383q1k9p-libnetfilter_conntrack-1.0.7
264K	/nix/store/4i1mw6av3d6pr9bqggb4hnv6cykbrhhi-kexec-tools-2.0.19
280K	/nix/store/4jw2677fvb11aj1bal9a2iksqz0mk80m-expat-2.2.6
312K	/nix/store/hg863b95fxv9zlk008qjyf87qgyx58h1-libseccomp-2.4.1-lib
316K	/nix/store/kvy2sz5lvi89lnh4rmw1df4jsnhqf1ay-libnftnl-1.1.2
380K	/nix/store/a2rr0irv2ssvvphvafgrxy4di0pkkagn-audit-2.8.5
408K	/nix/store/hfgblg8bdj328pbp9lmmf1wn58gq4b4s-xz-5.2.4
424K	/nix/store/rl2z4bb7wkfp0g12ccqffh287qal1109-kmod-26
448K	/nix/store/ndjjyr4rqibzkgs8w55bx2idhnckh39p-libidn2-2.1.1a
468K	/nix/store/6hwdmzpspbnb7ix5z6m9h60jyy42kj90-dbus-1.12.12-lib
504K	/nix/store/b85cjvwqsi39rb55dp2iv29iifnkcwa6-pcre-8.43
512K	/nix/store/vzjwz11r1yy02xv07vx2577pqizzx83n-nettle-3.4.1
544K	/nix/store/6b2jabk1scwhhk9bz7wjzycvmkiw419d-libapparmor-2.13.1
556K	/nix/store/caa29d4y2zip0ly9mcc7f4w94blw8k60-lz4-1.9.1
684K	/nix/store/daizqdqrm7g4favv814hnijmqhay8hs4-dbus-1.12.12
696K	/nix/store/m6hisb1d7q1c4z0s3icax40gynz4f8fl-gmp-6.1.2
884K	/nix/store/2j9jm3jaxfn2g6wxak61wkhmrg6c4nn5-unbound-1.9.1-lib
884K	/nix/store/xbcc8v50g7h7wqh892q7k22wb1ky8cg7-libevent-2.1.8
932K	/nix/store/yfmvcf5cslq4f9kv0vlmxksdgvick22d-libgpg-error-1.36
1.3M	/nix/store/94nrq9paz335s155x9za8n7kb0q3y211-libgcrypt-1.8.4
1.3M	/nix/store/jn0bddfc3fzhnf5ns4s2khhzclswvzb2-libpcap-1.9.0
1.4M	/nix/store/x0mlaj4z4ciycaycfwc36l1932mwywfj-bash-4.4-p23
1.5M	/nix/store/9hysgvp7qrfcil4b5qhwdq2vm9hism13-libxcb-1.13.1
1.5M	/nix/store/dglh318sp4xzybap1mm2mlcy8rv1nkl6-at-spi2-core-2.32.1
1.6M	/nix/store/mn0nzy294n07x1b92m9n0rwrv7z1441m-libunistring-0.9.10
1.7M	/nix/store/r6mrgd9k1jzzqrhphrg1qgxvgvbka7p8-pcre2-10.33
1.7M	/nix/store/rcn9d2q4mpapxf4qd54hkqz32ljhv0rw-util-linux-2.33.2
1.8M	/nix/store/a185xh0jcx7il7hw2gfh0pmvrah3x67y-systemd-239.20190219-lib
1.8M	/nix/store/bv1lw6a2kw0mn2y3lxhi43180idx6sp9-coreutils-8.31
2.7M	/nix/store/glx4vsd291jvbjzg49knldfq2mlhrpzn-glibc-2.27-bin
2.8M	/nix/store/1dydqkwswavzkyvr1qr62zmx3nqpmpp4-gnutls-3.6.7
3.2M	/nix/store/zh1q7yvyaxlcmj3n6g0rrdaq0v73pp90-linux-pam-1.3.1
3.4M	/nix/store/gsl1dw8ycrdvlzczsl59mkz0qpbwcmz1-iptables-1.8.2
3.5M	/nix/store/69vq0a9sqynmz335apm8zgyjdmq34s5j-libX11-1.6.7
3.5M	/nix/store/6whclwjzwg46s0dkxwk1xz8cdcxnkd3y-db-4.8.30
3.6M	/nix/store/qpj9rsal85rc94pizrkwb3c5nkivlfcl-p11-kit-0.23.14
3.6M	/nix/store/sm4yylq92rip64wdk3iniy91w48a90ia-openssl-1.0.2r
4.2M	/nix/store/2xhsrw4ws6kc4x3983wdwwlnim27c6iz-shadow-4.6
4.2M	/nix/store/lr9yhdbn8a3la69j56cz0vi1qva973dv-kbd-2.0.4
5.6M	/nix/store/jhah1057vq9d6j6jqzq0yhhlc6fybdj6-gcc-7.4.0-lib
5.6M	/nix/store/s7rqxrfb631i53dfl90gac35095jyypq-util-linux-2.33.2-bin
10M	/nix/store/znjkmjz0pgckxxzq0m9d17isnsd9s03q-cracklib-2.9.7
14M	/nix/store/yrmrvha03pvdyi9ww2bi6xjpk5930sf8-glib-2.60.1
23M	/nix/store/6bvd29jny80ka8df9prr5hrl5yz7d98k-systemd-239.20190219
30M	/nix/store/c745s6cnnxy6c98bvhi0qsijrh3ikag1-glibc-2.27
147M	total

The main reason this is important is because gtk3 depends on it and that is used by a bunch of other apps.

Steps to reproduce

Technical details

Please run nix-shell -p nix-info --run "nix-info -m" and paste the
results.

[jtojnar]

systemd is a transitive dependency of dbus (and cracklib of systemd via pam). We probably cannot get rid of glib or glibc and it would not be very helpful since GTK is based upon GLib. It should be probably possible to port it to gdbus which is part of GLib as many other programs did but since the public API depends on types from libdbus, it will not be possible in short term.

[jtojnar]

We could try to build some of these dependencies lighter but since almost everything comes from systemd closure, user will have it already installed.

[matthewbauer]

Yeah, I was hoping we could get rid of the dependency on systemd.out, which is pretty big. NixOS users will have systemd already installed but not necessarily for those installing outside of NixOS. systemd.lib is probably okay because it is so small.

$ nix why-depends -a /nix/store/dglh318sp4xzybap1mm2mlcy8rv1nkl6-at-spi2-core-2.32.1 /nix/store/6bvd29jny80ka8df9prr5hrl5yz7d98k-systemd-239.20190219
/nix/store/dglh318sp4xzybap1mm2mlcy8rv1nkl6-at-spi2-core-2.32.1
╚═══libexec/at-spi-bus-launcher: …a boolean but got %s./nix/store/daizqdqrm7g4favv814hnijmqhay8hs4-dbus-1.12.12/bin/dbus-daemon...…
    => /nix/store/daizqdqrm7g4favv814hnijmqhay8hs4-dbus-1.12.12
    ╚═══etc/systemd/user/dbus.socket: …t/bus.ExecStartPost=-/nix/store/6bvd29jny80ka8df9prr5hrl5yz7d98k-systemd-239.20190219/bin/system…
        => /nix/store/6bvd29jny80ka8df9prr5hrl5yz7d98k-systemd-239.20190219

Could we just add a bin output for dbus?

[jtojnar]

Sure, or just one for daemon. We can try but we need to be wary of cycles.

[Anton-Latukha]

1. systemd seems to be platforms = platforms.linux; - and curently a dependency of GTK, ATK. So a catch for GTK apps on macOS: Fix Handbrake build on Darwin by turning off GUI support #63643 (comment) summed in quote.

For Nix it seems to be a bummer that systemd seems not be able to be split & maintained splitted.
They saying it is "modular", it is obvious that it is very complicated now. Anyway I went and pocked a bit if someone has any results on splitting it. Seems no-one maintains splitted systemd:

• Repology stats on systemd-*: https://repology.org/projects/?search=systemd
• Previous Fedora package split: https://fedoraproject.org/wiki/Changes/systemd_package_split (& they seem not to maintain the split now)
• Openembedded trying to split: https://patchwork.openembedded.org/patch/88007/

2. So the solution untying D-Bus (real name of project libdbus) dependency on systemd on nonLinux seems to be a best solution. Seems like macOS supports libdbus.

[matthewbauer]

1. So the solution untying D-Bus (real name of project libdbus) dependency on systemd on nonLinux seems to be a best solution. Seems like macOS supports libdbus.

It does but I have not yet come across an app that needs it. Most macOS users won't have dbus running, so compiling with libdbus support could lead to issues. Ideally we could make all of these dependencies optional. In some cases it doesn't make sense because libappindicator-gtk3, but those should be optional dependencies anyway.

[stale]

Thank you for your contributions.

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[YoshiRulz]

Did #66634 only fix this for NixOS? I'm seeing systemd-249.5 adding ~100 MiB to the closure of at-spi2-core-2.42.0 on non-NixOS.

Issue title has a typo in the package name BTW.

[jtojnar]

That is correct, the dbus-daemon path is hardcoded so the program will not be able to work outside of NixOS. Although I would expect that to not matter since on different system, we would use their own global accessibility match any way.

Also note that the closure size will get worse with the upcoming #176156.