[master] rpm: patch RLIMIT_NOFILE for EL 7 systems

[neersighted]

RLIMIT_NOFILE defaults to an unusable value on EL 7 systems, but more modern systems have sane defaults. As such, patch the systemd unit only on EL 7 systems to ensure correct behaviour.

[thaJeztah]

Looks like containerd did not (yet) backport that change to 1.6 and 1.7, but we need to keep an eye in case they do;

• https://github.com/containerd/containerd/blob/v1.7.9/containerd.service
• https://github.com/containerd/containerd/blob/v1.6.25/containerd.service

Or we could consider doing the reverse, and patching the containerd systemd unit to (conditionally) remove the LimitNOFILE=infinity

[thaJeztah]

Unrelated, but now wondering what version of systemd RHEL/CentOS 7 are running, and if this comment is still relevant (ISTR it was always just a warning, so not even sure if relevant at all)

[neersighted]

219: https://centos.pkgs.org/7/centos-x86_64/systemd-sysv-219-78.el7.x86_64.rpm.html

[thaJeztah]

Looks like something is failing. Could be due to some of the indirections / shuffling of paths that things are not where you expect them to be (I definitely banged my head against a wall in the past on that matter);

cp /home/ubuntu/workspace/docker-ce-packaging_PR-968/rpm/patches/rpmbuild/SOURCES/01-rlimit_nofile-rhel7.patch rpmbuild/SOURCES
cp: cannot stat '/home/ubuntu/workspace/docker-ce-packaging_PR-968/rpm/patches/rpmbuild/SOURCES/01-rlimit_nofile-rhel7.patch': No such file or directory
make[1]: *** [Makefile:98: rpmbuild/SOURCES/01-rlimit_nofile-rhel7.patch] Error 1
make[1]: Leaving directory '/home/ubuntu/workspace/docker-ce-packaging_PR-968/rpm'
make: *** [Makefile:79: centos-7] Error 2
script returned exit code 2

[neersighted]

Yeah, thought I had this working but I was disentangling it from other changes I was testing last week; will fiddle with the paths a bit.

[thaJeztah]

LGTM