(WIP) stage1: app exit code propagated to rkt exit code

[alban]

This only works with systemd-v228 in stage1 because it uses the new
command "systemctl exit". You can try with:

sh autogen.sh && ./configure \
  --with-stage1-flavors=src \
  --enable-functional-tests \
  --with-stage1-systemd-version=v228 \
  && make

I disabled machine registration because of issue #1782.

Fixes #1460

[vcaputo]

neat

Though I figured we wouldn't go down this route since it will be ambiguous which app's return value propagated out, it makes sense when you have a single app running within the pod, but the multi-app pod is awkward.

[alban]

Though I figured we wouldn't go down this route since it will be ambiguous which app's return value propagated out, it makes sense when you have a single app running within the pod, but the multi-app pod is awkward.

This might change later when ExitPolicy={untilAll,onAny,onAnyFailure} gets implemented (see appc/spec#500) but at the moment, rkt implements the semantics of ExitPolicy=onAnyFailure via the systemd unit files in stage1.

So there can be only one app failing because the pod stops when any app exits with a failure. The return value returned is just the one from the failing app. If the user want to know which app it is, they have to use rkt status.

If an app terminates successfully (return value 0), reaper.sh does not call systemctl exit so the return value of the pod is not changed. I think this is good enough because in most case we just want to know if the pod succeed (return value == 0) or failed (return value != 0).

[iaguis]

Waiting for a systemd v229 release.