Re: [libvirt] [PATCH v2 3/3] libxl: add hooks support

Introduce libxl hook and use it for start, prepare, started, stop, stopped, migrate events. --- docs/hooks.html.in | 53 ++++++++++++++++++++++++++++++-- src/libxl/libxl_domain.c | 74 +++++++++++++++++++++++++++++++++++++++++++++ src/libxl/libxl_driver.c | 22 ++++++++++++++ src/libxl/libxl_migration.c | 57 ++++++++++++++++++++++++++++++++++ src/util/virhook.c | 16 +++++++++- src/util/virhook.h | 13 ++++++++ 6 files changed, 232 insertions(+), 3 deletions(-) diff --git a/docs/hooks.html.in b/docs/hooks.html.in index d4f4ac3..11073cb 100644 --- a/docs/hooks.html.in +++ b/docs/hooks.html.in @@ -17,8 +17,10 @@ (<span class="since">since 0.8.0</span>)<br/><br/></li> <li>A QEMU guest is started or stopped (<span class="since">since 0.8.0</span>)<br/><br/></li> - <li>An LXC guest is started or stopped + <li>An LXC guest is started or stopped (<span class="since">since 0.8.0</span>)<br/><br/></li> + <li>A libxl-handled Xen guest is started or stopped + (<span class="since">since 2.1.0</span>)<br/><br/></li> <li>A network is started or stopped or an interface is plugged/unplugged to/from the network (<span class="since">since 1.2.2</span>)<br/><br/></li> @@ -41,7 +43,7 @@ <br/> <h2><a name="names">Script names</a></h2> - <p>At present, there are three hook scripts that can be called:</p> + <p>At present, there are five hook scripts that can be called:</p> <ul> <li><code>/etc/libvirt/hooks/daemon</code><br/><br/> Executed when the libvirt daemon is started, stopped, or reloads @@ -50,6 +52,9 @@ Executed when a QEMU guest is started, stopped, or migrated<br/><br/></li> <li><code>/etc/libvirt/hooks/lxc</code><br /><br/> Executed when an LXC guest is started or stopped</li> + <li><code>/etc/libvirt/hooks/libxl</code><br/><br/> + Executed when a libxl-handled Xen guest is started, stopped, or + migrated<br/><br/></li> <li><code>/etc/libvirt/hooks/network</code><br/><br/> Executed when a network is started or stopped or an interface is plugged/unplugged to/from the network</li> @@ -235,6 +240,50 @@ </li> </ul> + <h5><a name="libxl">/etc/libvirt/hooks/libxl</a></h5> + <ul> + <li>Before a Xen guest is started using libxl driver, the libxl hook + script is called in three locations; if any location fails, the guest + is not started. The first location, <span class="since">since + 2.1.0</span>, is before libvirt performs any resource + labeling, and the hook can allocate resources not managed by + libvirt. This is called as:<br/> + <pre>/etc/libvirt/hooks/libxl guest_name prepare begin -</pre> + The second location, available <span class="since">Since + 2.1.0</span>, occurs after libvirt has finished labeling + all resources, but has not yet started the guest, called as:<br/> + <pre>/etc/libvirt/hooks/libxl guest_name start begin -</pre> + The third location, <span class="since">2.1.0</span>, + occurs after the domain has successfully started up:<br/> + <pre>/etc/libvirt/hooks/libxl guest_name started begin -</pre> + </li> + <li>When a libxl-handled Xen guest is stopped, the libxl hook script + is called in two locations, to match the startup. + First, <span class="since">since 2.1.0</span>, the hook is + called before libvirt restores any labels:<br/> + <pre>/etc/libvirt/hooks/libxl guest_name stopped end -</pre> + Then, after libvirt has released all resources, the hook is + called again, <span class="since">since 2.1.0</span>, to allow + any additional resource cleanup:<br/> + <pre>/etc/libvirt/hooks/libxl guest_name release end -</pre></li> + <li><span class="since">Since 2.1.0</span>, the libxl hook script + is also called at the beginning of incoming migration. It is called + as: <pre>/etc/libvirt/hooks/libxl 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, e.g., to change + location of disk images for incoming domains.</li> + <li><span class="since">Since 2.1.0</span>, the libxl hook script + is also called when the libvirtd daemon restarts and reconnects + to previously running Xen domains. If the script fails, the + existing Xen domains will be killed off. It is called as: + <pre>/etc/libvirt/hooks/libxl guest_name reconnect begin -</pre> + </li> + </ul> + <h5><a name="network">/etc/libvirt/hooks/network</a></h5> <ul> <li><span class="since">Since 1.2.2</span>, before a network is started, diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c index 886b40f..d99f903 100644 --- a/src/libxl/libxl_domain.c +++ b/src/libxl/libxl_domain.c @@ -32,6 +32,7 @@ #include "viratomic.h" #include "virfile.h" #include "virerror.h" +#include "virhook.h" #include "virlog.h" #include "virstring.h" #include "virtime.h" @@ -737,6 +738,17 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver, hostdev_flags |= VIR_HOSTDEV_SP_USB; #endif + /* now that we know it's stopped call the hook if present */ + if (virHookPresent(VIR_HOOK_DRIVER_LIBXL)) { + char *xml = virDomainDefFormat(vm->def, cfg->caps, 0); + + /* we can't stop the operation even if the script raised an error */ + ignore_value(virHookCall(VIR_HOOK_DRIVER_LIBXL, vm->def->name, + VIR_HOOK_LIBXL_OP_STOPPED, VIR_HOOK_SUBOP_END, + NULL, xml, NULL));

+ VIR_FREE(xml); + } + virHostdevReAttachDomainDevices(hostdev_mgr, LIBXL_DRIVER_NAME, vm->def, hostdev_flags, NULL); @@ -788,6 +800,17 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver, VIR_FREE(file); } + /* The "release" hook cleans up additional resources */ + if (virHookPresent(VIR_HOOK_DRIVER_LIBXL)) { + char *xml = virDomainDefFormat(vm->def, cfg->caps, 0); + + /* we can't stop the operation even if the script raised an error */ + ignore_value(virHookCall(VIR_HOOK_DRIVER_LIBXL, vm->def->name, + VIR_HOOK_LIBXL_OP_RELEASE, VIR_HOOK_SUBOP_END, + NULL, xml, NULL);

+ VIR_FREE(xml); + } +