[libvirt] [PATCH v2 3/3] libxl: add hooks support
Michal Privoznik
mprivozn at redhat.com
Tue Aug 2 13:38:32 UTC 2016
On 28.07.2016 11:57, Cédric Bosdonnat wrote:
> 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));
Here ^^
> + 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);
And here ^^^ I'd drop the ignore_value(). The virHookCall() is not
declared with CHECK_RETURN, so there's no need for ignore_value() macro.
> + VIR_FREE(xml);
> + }
> +
Michal
More information about the libvir-list
mailing list