RFC: disable service start/stop for offline updates
Needs ReviewPublic

Authored by sitter on Mon, Nov 26, 1:07 PM.

Details

Summary

during offline updates we run in a minimal system with few services started
and we do actually not want to start any additional services. because of
the minimal nature this may also result in services timing out as they
won't be able to bind network interfaces or any other reason really.
to that end prevent any services from even attempting to start by
installing a policy-rc.d will prevent offline updates for getting stuck
for 90 or so seconds until a service may decide to fail starting.

system-update.target wants a special helper which binds our policy-rc.d
into place, default.target may clean up an empty policy-rc.d if
necessary.
should the user have a policy-rc.d we'll not destroy them, and thanks
to the bind mount our override will not persist across the reboot out of
system-update.target. the ultimate target is an ephemeral policy-rc.d.

Test Plan

did an update. policy-rc.d was managed as described

Diff Detail

Branch
Neon/unstable
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Unit
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Build Status
Buildable 5382
Build 5400: arc lint + arc unit
sitter requested review of this revision.Mon, Nov 26, 1:07 PM
sitter created this revision.