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[Scott Moser <ssmoser2+ubuntu@xxxxxxxxx>]

Nominated this for xenial based on bug 1651497.


** Also affects: open-iscsi (Ubuntu Xenial)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1755858

Title:
  iscsid autostarts on all servers when it has nothing to do

Status in open-iscsi package in Ubuntu:
  Fix Released
Status in open-iscsi source package in Xenial:
  New
Status in open-iscsi source package in Bionic:
  Triaged
Status in open-iscsi package in Debian:
  New

Bug description:
  [Impact]

   * Service is running uselessly which is consuming a few cycles/memory as
     well as rasising general concerns e.g. on minimizing attack surfcae of
     a system.

   * This is also the only service in a default server install which
  pulls in the network-online.target, which has implications for boot
  ordering and speed in various configurations.

   * Fix by switching to socket activation

  [Test Case]

   * After installing open-iscsi (which is default installed) the service
     iscsid is running which is mostly useless
   * After the upgrade only the iscsid.socket should run
   * Ensure that iscsid.service should come up as needed

  [Regression Potential]

   * I'm not sure we can/shall SRU this, but was asked to express my
     thoughts in the regression potential. It is not that it would not
     "work", we tested in cosmic and so far all is fine - the tools will
     call the abstract socket and it will spawn.
     So it is not that I see it totally "failing"
   * I'd more be concerned that one would have e.g. scripts and other upper
     level code that does like:
       if service-is-not-running; then break; else do what you should do
     This would give up before socket-triggering it which might be too much
     to SRU. On a Upgrade to a newer release such minor adaptions are usual,
     but for SRUs?
   * But also we don't stop the service on upgrade (for safety of the data),
     so you'd have four different Bionics
     a) old iscsid.service runnign by default
     b) upgraded, but not rebooted iscsid.service still running
     c) upgraded, rebooted iscid.service disabled,
        iscsid.socket running
     d) new deploy after this (e.g. new cloud image) iscid.service disabled,
        iscsid.socket running
     a+b are similar as well as c+d.
   * OTOH there are a few things reducing this impact, first of all this is
     a config, so one can "systemctl enable iscsid.service" and will have
     the old behavior
   * Is this a real blocker, I'm not sure - so I documented as requested and
     would want the SRU team to discuss before an upload.

  [Other Info]

   * n/a

  ---

  In bionic, the open-iscsi systemd unit has the following guards to
  keep it from running on systems with no iscsi targets configured:

  # Must have some pre-defined targets to login to
  ConditionDirectoryNotEmpty=|/etc/iscsi/nodes
  # or have a session to use via iscsid
  ConditionDirectoryNotEmpty=|/sys/class/iscsi_session

  However, iscsid starts from a separate unit and does not include this
  check.  Thus, iscsid starts on every Ubuntu Server install, whether or
  not it has anything to do.

  We should replicate these unit conditionals to the iscsid unit, to
  ensure the daemon doesn't run (consuming memory, and slowing boot)
  when not needed.

  Related bugs:
   * bug 1630946: ubuntu-server depends on open-iscsi and runs iscsid

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