kvm: set LIBVIRTD_ARGS so libvirtd listens on Debian and Ubuntu hosts

[nagaboinaramgopal]

Description

cloudstack-setup-agent sets up live migration on Debian and Ubuntu by writing libvirtd_opts='-l' to /etc/default/libvirtd and masking the libvirtd sockets. The libvirtd.service unit on current releases reads LIBVIRTD_ARGS from that file instead (Debian 12 and 13: ExecStart=/usr/sbin/libvirtd $LIBVIRTD_ARGS with --timeout 120 as the default), so after adding a host libvirtd runs without --listen, nothing listens on 16509/16514 and live migration fails. This also sets LIBVIRTD_ARGS="--listen", and keeps libvirtd_opts for older units that still read it.

Related: #9802 and #12374.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• build/CI
• test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

N/A

How Has This Been Tested?

Live tested on two fresh Debian 13 KVM hosts (libvirt 11.3, QEMU 10.0) added to a cluster with addHost, with NFS primary storage, and a VM live migrated between them with migrateVirtualMachine.

Before this change, right after addHost:

/etc/default/libvirtd   libvirtd_opts='-l'
libvirtd process        /usr/sbin/libvirtd --timeout 120
ports 16509/16514       nothing listening

15:51:27 GET command=migrateVirtualMachine&virtualmachineid=...&hostid=...
15:51:28 ERROR [LibvirtMigrateCommandWrapper] Can't migrate domain due to: [unable to connect to server at '<destination host>:16509': Connection refused]
15:51:28 Complete async job-1640, jobStatus: FAILED, resultCode: 530, "Failed to migrate domain"

With this change, same hosts reset to the distro defaults and added again:

/etc/default/libvirtd   libvirtd_opts='-l'
                        LIBVIRTD_ARGS="--listen"
libvirtd process        /usr/sbin/libvirtd --listen
port 16514              listening

15:58:25 GET command=migrateVirtualMachine&virtualmachineid=...&hostid=...
15:58:28 Complete async job-1653, jobStatus: SUCCEEDED

Debian 12 (libvirt 9.0) uses the same unit layout.

How did you try to break this feature and the system with this change?

Older units that read libvirtd_opts still get it. replace_or_add_line replaces an existing or commented LIBVIRTD_ARGS line, so adding a host again does not duplicate it. The RHEL and SUSE paths are unchanged.

[weizhouapache]

code lgtm

we have not faced this issue in Trillian tests, as we have already applied it via ansible

- name: Update /etc/default/libvirtd in Ubuntu 22.04
  lineinfile:
    dest: "/etc/default/libvirtd"
    regexp: '^LIBVIRTD_ARGS=*'
    line: 'LIBVIRTD_ARGS="-l"'
  when: ansible_distribution_version is version('22.04','>=')

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 16.38%. Comparing base (8261bec) to head (e31f9a0).

Additional details and impacted files

@@             Coverage Diff              @@
##               4.20   #14153      +/-   ##
============================================
- Coverage     16.38%   16.38%   -0.01%     
+ Complexity    13615    13614       -1     
============================================
  Files          5669     5669              
  Lines        501561   501561              
  Branches      60922    60922              
============================================
- Hits          82168    82167       -1     
- Misses       410185   410186       +1     
  Partials       9208     9208              

Flag	Coverage Δ
uitests	4.16% <ø> (ø)
unittests	17.24% <ø> (-0.01%)	⬇️

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