Re: [libvirt] [PATCH 2/2] qemu: Add pre-migration hook

This hook is called during the Prepare phase on destination host and may be used for changing domain XML. --- docs/hooks.html.in | 35 +++++++++++++++++++++++------------ src/qemu/qemu_migration.c | 40 ++++++++++++++++++++++++++++++++++++++++ src/util/hooks.c | 3 ++- src/util/hooks.h | 1 + 4 files changed, 66 insertions(+), 13 deletions(-) diff --git a/docs/hooks.html.in b/docs/hooks.html.in index 890359e..6c82c6d 100644 --- a/docs/hooks.html.in +++ b/docs/hooks.html.in @@ -120,6 +120,16 @@ called again, <span class="since">since 0.9.0</span>, to allow any additional resource cleanup:<br/> <pre>/etc/libvirt/hooks/qemu guest_name release end -</pre></li> + <li><span class="since">Since 0.9.11</span>, the qemu hook script + is also called at the beginning of incoming migration. It is called + as: <pre>/etc/libvirt/hooks/qemu guest_name migrate begin -</pre> + with domain XML sent to standard input of the script. In this case, + the script acts as a filter and is supposed to modify the domain + XML and print it out on its standard output. Empty output is + identical to copying the input XML without changing it. In case the + script returns failure or the output XML is not valid, incoming + migration will be canceled. This hook may be used to, e.g., change

+ location of disk images for incoming domains.</li> </ul> <h5><a name="lxc">/etc/libvirt/hooks/lxc</a></h5> @@ -161,19 +171,20 @@ source and destination hosts:</p> <ol> <li>At the beginning of the migration, the <i>qemu</i> hook script on - the <b>destination</b> host is executed with the "start" - operation.<br/><br/></li> - <li>If this hook script returns indicating success (error code 0), the - migration continues. Any other return code indicates failure, and - the migration is aborted.<br/><br/></li> - <li>The QEMU guest is then migrated to the destination host.<br/> - <br/></li> + the <b>destination</b> host is executed with the "migrate" + operation.</li> + <li>Before QEMU process is spawned, the two operations ("prepare" and + "start") called for domain start are executed on + <b>destination</b> host.</li> + <li>If any of these hook script executions returns indicating success + (error code 0), the migration continues. Any other return code + indicates failure, and the migration is aborted.</li>

@@ -1150,6 +1152,43 @@ qemuMigrationPrepareAny(struct qemud_driver *driver, goto cleanup; } + /* Let migration hook filter domain XML */ + if (virHookPresent(VIR_HOOK_DRIVER_QEMU)) { + char *xml = virDomainDefFormat(def, VIR_DOMAIN_XML_SECURE); + int hookret; + + hookret = virHookCall(VIR_HOOK_DRIVER_QEMU, def->name, + VIR_HOOK_QEMU_OP_MIGRATE, VIR_HOOK_SUBOP_BEGIN, + NULL, xml, &xmlout);