[Bug 1821255] [NEW] Restart policy "Always" doesn't work under certain circumstances

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Ubuntu Foundations Team Bug Bot (crichton):

[Impact]
iscsid restart fails when killed with SIGTERM

[Description]
If systemd tries to execute a command that talks to iscsid via iscsid.socket, it can hang if iscsid is not running (or is in the process of being stopped). This can happen due to the current ExecStop= directive, which calls iscsiadm to kill iscsid, and prevents the service from being restarted even when we set Restart=always in the iscsid unit file.

The solution is to let systemd terminate iscsid by itself. The default action
when omitting the ExecStop directive is to send SIGTERM to the process group,
which is equivalent to invoking "iscsiadm -k" (the current ExecStop command).

[Test Case]
1) Deploy a Disco VM e.g. with uvt-kvm
    $ uvt-kvm create disco release=disco

2) Run the deploy-tgt.sh script in the VM to setup an iSCSI target in the
localhost. The script will install tgt and open-iscsi, configure a 1G
file-backed iSCSI target, login and restart iscsid.service
    ubuntu at disco:~$ ./deploy-tgt.sh

3) Kill iscsid with SIGTERM
    ubuntu at disco:~$ sudo pkill iscsid

4) Try to stop iscsid.service and check whether it hangs
    ubuntu at disco:~$ sudo systemctl stop iscsid

If we remove the ExecStop= directive, it works as expected:
    ubuntu at disco:~$ sudo systemctl stop iscsid
    ubuntu at disco:~$
This also causes Restart=always to work as expected.

[Regression Potential]
This shouldn't introduce any regressions, since iscsiadm -k just sends SIGTERM to iscsid's process group and that's equivalent to the default systemd ExecStop action. Nonetheless, changes will be tested with autopkgtests and different iscsi scenarios.

** Affects: open-iscsi (Ubuntu)
     Importance: High
     Assignee: Heitor R. Alves de Siqueira (halves)
         Status: In Progress

** Affects: open-iscsi (Ubuntu Bionic)
     Importance: High
     Assignee: Heitor R. Alves de Siqueira (halves)
         Status: Confirmed

** Affects: open-iscsi (Ubuntu Cosmic)
     Importance: High
     Assignee: Heitor R. Alves de Siqueira (halves)
         Status: Confirmed

** Affects: open-iscsi (Ubuntu Disco)
     Importance: High
     Assignee: Heitor R. Alves de Siqueira (halves)
         Status: In Progress


** Tags: patch sts sts-sponsor
-- 
Restart policy "Always" doesn't work under certain circumstances
https://bugs.launchpad.net/bugs/1821255
You received this bug notification because you are a member of Ubuntu Sponsors Team, which is subscribed to the bug report.