This commit introduces a feature enhancement for configuring hostnames in virtual machines (VMs) using DHCP. It adds new options to the "passt" tool to set the hostname and fully qualified domain name (FQDN) for VMs. These map to DHCP option 12 for the hostname and options 81 (IPv4) and 39 (IPv6) for the FQDN. The update enables passt to dynamically assign hostnames to DHCP-aware VMs. To achieve this, the commit adds two fields to the passt domain XML backend. These fields allow passt to configure the hostname and FQDN for the virtual machine, ensuring smooth integration with the DHCP protocol. This improvement is particularly valuable in environments where VMs need dynamic hostname configuration, enhancing flexibility and automation in virtualized network setups. libvirt: Integrate passt --hostname --fqdn options Resolves: https://issues.redhat.com/browse/RHEL-79806 Signed-off-by: Enrique Llorente <ellorent(a)redhat.com&gt; --- Compared to v1 this fix the mapping between backend fqdn and hostname docs/formatdomain.rst | 8 +++++--- src/conf/domain_conf.c | 10 +++++++++- src/conf/domain_conf.h | 2 ++ src/conf/schemas/domaincommon.rng | 6 ++++++ src/qemu/qemu_passt.c | 6 ++++++ tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml | 2 +- tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml | 2 +- tests/qemuxmlconfdata/net-user-passt.xml | 2 +- .../net-vhostuser-passt.x86_64-latest.xml | 2 +- tests/qemuxmlconfdata/net-vhostuser-passt.xml | 2 +- 10 files changed, 33 insertions(+), 9 deletions(-) diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index 8753ee9c23..9c80aa9270 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -5372,10 +5372,12 @@ came from the host's IP. There are a few other options that are configurable only for the passt backend. For example, the ``<backend>`` attribute ``logFile`` can be used to tell the passt process for this interface where to write its -message log, and the ``<source>`` attribute ``dev`` can tell it a +message log, the ``<source>`` attribute ``dev`` can tell it a particular host interface to use when deriving the routes given to the -guest for forwarding traffic upstream. Due to the design decisions of -passt, when using SELinux on the host, it is recommended that the log +guest for forwarding traffic upstream and the ``hostname`` and ``fqdn`` +will conigure the DHCP option 12 hostname and DHCP option 81 and DHCPv6 +option 39 fqdn attribute. Due to the design decisions of passt, when using +SELinux on the host, it is recommended that the log file reside in the runtime directory of the user under which the passt process will run, most probably ``/run/user/$UID`` (where ``$UID`` is the UID of that user), e.g. ``/run/user/1000``. Be aware that libvirt diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index b3b0bd7329..15143f8fa2 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -2909,6 +2909,8 @@ virDomainNetDefFree(virDomainNetDef *def) g_free(def->backend.tap); g_free(def->backend.vhost); g_free(def->backend.logFile); + g_free(def->backend.hostname); + g_free(def->backend.fqdn); virDomainNetTeamingInfoFree(def->teaming); g_free(def->virtPortProfile); g_free(def->script); @@ -9757,6 +9759,8 @@ virDomainNetBackendParseXML(xmlNodePtr node, } def->backend.logFile = virXMLPropString(node, "logFile"); + def->backend.hostname = virXMLPropString(node, "hostname"); + def->backend.fqdn = virXMLPropString(node, "fqdn"); if (tap) def->backend.tap = virFileSanitizePath(tap); @@ -20757,7 +20761,9 @@ virDomainNetBackendIsEqual(virDomainNetBackend *src, if (src->type != dst->type || STRNEQ_NULLABLE(src->tap, dst->tap) || STRNEQ_NULLABLE(src->vhost, dst->vhost) || - STRNEQ_NULLABLE(src->logFile, dst->logFile)) { + STRNEQ_NULLABLE(src->logFile, dst->logFile) || + STRNEQ_NULLABLE(src->hostname, dst->hostname) || + STRNEQ_NULLABLE(src->fqdn, dst->fqdn)) { return false; } return true; @@ -24838,6 +24844,8 @@ virDomainNetBackendFormat(virBuffer *buf, virBufferEscapeString(&attrBuf, " tap='%s'", backend->tap); virBufferEscapeString(&attrBuf, " vhost='%s'", backend->vhost); virBufferEscapeString(&attrBuf, " logFile='%s'", backend->logFile); + virBufferEscapeString(&attrBuf, " hostname='%s'", backend->hostname); + virBufferEscapeString(&attrBuf, " fqdn='%s'", backend->fqdn); virXMLFormatElement(buf, "backend", &attrBuf, NULL); } diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 58b97a2b54..79fd2f1f63 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1067,6 +1067,8 @@ struct _virDomainNetBackend { char *vhost; /* The following are currently only valid/used when backend type='passt' */ char *logFile; /* path to logfile used by passt process */ + char *hostname; /* hostname of the passt process */ + char *fqdn; /* fully qualified domain name of the passt process */ }; struct _virDomainNetPortForwardRange { diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng index 5597d5a66b..f64199ca18 100644 --- a/src/conf/schemas/domaincommon.rng +++ b/src/conf/schemas/domaincommon.rng @@ -3913,6 +3913,12 @@ <ref name="absFilePath"/> </attribute> </optional> + <optional> + <attribute name="hostname"/> + </optional> + <optional> + <attribute name="fqdn"/> + </optional> </element> </optional> <optional> diff --git a/src/qemu/qemu_passt.c b/src/qemu/qemu_passt.c index fcc34de384..81e5c51f6c 100644 --- a/src/qemu/qemu_passt.c +++ b/src/qemu/qemu_passt.c @@ -229,6 +229,12 @@ qemuPasstStart(virDomainObj *vm, if (net->backend.logFile) virCommandAddArgList(cmd, "--log-file", net->backend.logFile, NULL); + if (net->backend.hostname) + virCommandAddArgList(cmd, "--hostname", net->backend.hostname, NULL); + + if (net->backend.fqdn) + virCommandAddArgList(cmd, "--fqdn", net->backend.fqdn, NULL); + /* Add IP address info */ for (i = 0; i < net->guestIP.nips; i++) { const virNetDevIPAddr *ip = net->guestIP.ips[i]; diff --git a/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml b/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml index cfe07cc627..77da297936 100644 --- a/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml +++ b/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml @@ -50,7 +50,7 @@ <range start='443' to='344'/> </portForward> <model type='rtl8139'/> - <backend type='passt' logFile='/var/log/loglaw.blog'/> + <backend type='passt' logFile='/var/log/loglaw.blog' hostname='hostname1' fqdn='hostname1.test.local'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </interface> <input type='mouse' bus='ps2'/> diff --git a/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml b/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml index d7e0ef5f90..917a9edaa0 100644 --- a/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml +++ b/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml @@ -50,7 +50,7 @@ <range start='443' to='344'/> </portForward> <model type='rtl8139'/> - <backend type='passt' logFile='/var/log/loglaw.blog'/> + <backend type='passt' logFile='/var/log/loglaw.blog' hostname='hostname1' fqdn='hostname1.test.local'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </interface> <input type='mouse' bus='ps2'/> diff --git a/tests/qemuxmlconfdata/net-user-passt.xml b/tests/qemuxmlconfdata/net-user-passt.xml index 20c9f50542..80d15de2ed 100644 --- a/tests/qemuxmlconfdata/net-user-passt.xml +++ b/tests/qemuxmlconfdata/net-user-passt.xml @@ -47,7 +47,7 @@ <range start='443' to='344'/> </portForward> <model type='rtl8139'/> - <backend type='passt' logFile='/var/log/loglaw.blog'/> + <backend type='passt' logFile='/var/log/loglaw.blog' hostname='hostname1' fqdn='hostname1.test.local'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </interface> <input type='mouse' bus='ps2'/> diff --git a/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml b/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml index 529aff11f8..5802754c4b 100644 --- a/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml +++ b/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml @@ -53,7 +53,7 @@ <range start='443' to='344'/> </portForward> <model type='virtio'/> - <backend type='passt' logFile='/var/log/loglaw.blog'/> + <backend type='passt' logFile='/var/log/loglaw.blog' hostname='hostname1' fqdn='hostname1.test.local'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </interface> <interface type='vhostuser'> diff --git a/tests/qemuxmlconfdata/net-vhostuser-passt.xml b/tests/qemuxmlconfdata/net-vhostuser-passt.xml index 71b845329b..0a37511a0f 100644 --- a/tests/qemuxmlconfdata/net-vhostuser-passt.xml +++ b/tests/qemuxmlconfdata/net-vhostuser-passt.xml @@ -50,7 +50,7 @@ <range start='443' to='344'/> </portForward> <model type='virtio'/> - <backend type='passt' logFile='/var/log/loglaw.blog'/> + <backend type='passt' logFile='/var/log/loglaw.blog' hostname='hostname1' fqdn='hostname1.test.local'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </interface> <interface type='vhostuser'> -- 2.49.0 Build libvirt-11.5 with this patch. It works for me.

On Mon, Jun 23, 2025 at 5:39 PM Han Han <hhan(a)redhat.com&gt; wrote: > > > On Fri, May 30, 2025 at 8:22 PM Enrique Llorente via Devel < > devel(a)lists.libvirt.org&gt; wrote: > >> This commit introduces a feature enhancement for configuring hostnames in >> virtual machines (VMs) using DHCP. It adds new options to the "passt" >> tool >> to set the hostname and fully qualified domain name (FQDN) for VMs. These >> map to DHCP option 12 for the hostname and options 81 (IPv4) and 39 >> (IPv6) >> for the FQDN. >> >> The update enables passt to dynamically assign hostnames to DHCP-aware >> VMs. To achieve this, the commit adds two fields to the passt domain XML >> backend. These fields allow passt to configure the hostname and FQDN for >> the virtual machine, ensuring smooth integration with the DHCP protocol. >> >> This improvement is particularly valuable in environments where VMs need >> dynamic hostname configuration, enhancing flexibility and automation in >> virtualized network setups. >> >> libvirt: Integrate passt --hostname --fqdn options >> Resolves: https://issues.redhat.com/browse/RHEL-79806 >> >> Signed-off-by: Enrique Llorente <ellorent(a)redhat.com&gt; >> --- >> Compared to v1 this fix the mapping between backend fqdn and hostname >> >> docs/formatdomain.rst | 8 +++++--- >> src/conf/domain_conf.c | 10 +++++++++- >> src/conf/domain_conf.h | 2 ++ >> src/conf/schemas/domaincommon.rng | 6 ++++++ >> src/qemu/qemu_passt.c | 6 ++++++ >> tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml | 2 +- >> tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml | 2 +- >> tests/qemuxmlconfdata/net-user-passt.xml | 2 +- >> .../net-vhostuser-passt.x86_64-latest.xml | 2 +- >> tests/qemuxmlconfdata/net-vhostuser-passt.xml | 2 +- >> 10 files changed, 33 insertions(+), 9 deletions(-) >> >> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst >> index 8753ee9c23..9c80aa9270 100644 >> --- a/docs/formatdomain.rst >> +++ b/docs/formatdomain.rst >> @@ -5372,10 +5372,12 @@ came from the host's IP. >> There are a few other options that are configurable only for the passt >> backend. For example, the ``<backend>`` attribute ``logFile`` can be >> used to tell the passt process for this interface where to write its >> -message log, and the ``<source>`` attribute ``dev`` can tell it a >> +message log, the ``<source>`` attribute ``dev`` can tell it a >> particular host interface to use when deriving the routes given to the >> -guest for forwarding traffic upstream. Due to the design decisions of >> -passt, when using SELinux on the host, it is recommended that the log >> +guest for forwarding traffic upstream and the ``hostname`` and ``fqdn`` >> +will conigure the DHCP option 12 hostname and DHCP option 81 and DHCPv6 >> +option 39 fqdn attribute. Due to the design decisions of passt, when >> using >> +SELinux on the host, it is recommended that the log >> file reside in the runtime directory of the user under which the passt >> process will run, most probably ``/run/user/$UID`` (where ``$UID`` is >> the UID of that user), e.g. ``/run/user/1000``. Be aware that libvirt >> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c >> index b3b0bd7329..15143f8fa2 100644 >> --- a/src/conf/domain_conf.c >> +++ b/src/conf/domain_conf.c >> @@ -2909,6 +2909,8 @@ virDomainNetDefFree(virDomainNetDef *def) >> g_free(def->backend.tap); >> g_free(def->backend.vhost); >> g_free(def->backend.logFile); >> + g_free(def->backend.hostname); >> + g_free(def->backend.fqdn); >> virDomainNetTeamingInfoFree(def->teaming); >> g_free(def->virtPortProfile); >> g_free(def->script); >> @@ -9757,6 +9759,8 @@ virDomainNetBackendParseXML(xmlNodePtr node, >> } >> >> def->backend.logFile = virXMLPropString(node, "logFile"); >> + def->backend.hostname = virXMLPropString(node, "hostname"); >> + def->backend.fqdn = virXMLPropString(node, "fqdn"); >> >> if (tap) >> def->backend.tap = virFileSanitizePath(tap); >> @@ -20757,7 +20761,9 @@ virDomainNetBackendIsEqual(virDomainNetBackend >> *src, >> if (src->type != dst->type || >> STRNEQ_NULLABLE(src->tap, dst->tap) || >> STRNEQ_NULLABLE(src->vhost, dst->vhost) || >> - STRNEQ_NULLABLE(src->logFile, dst->logFile)) { >> + STRNEQ_NULLABLE(src->logFile, dst->logFile) || >> + STRNEQ_NULLABLE(src->hostname, dst->hostname) || >> + STRNEQ_NULLABLE(src->fqdn, dst->fqdn)) { >> return false; >> } >> return true; >> @@ -24838,6 +24844,8 @@ virDomainNetBackendFormat(virBuffer *buf, >> virBufferEscapeString(&attrBuf, " tap='%s'", backend->tap); >> virBufferEscapeString(&attrBuf, " vhost='%s'", backend->vhost); >> virBufferEscapeString(&attrBuf, " logFile='%s'", backend->logFile); >> + virBufferEscapeString(&attrBuf, " hostname='%s'", >> backend->hostname); >> + virBufferEscapeString(&attrBuf, " fqdn='%s'", backend->fqdn); >> virXMLFormatElement(buf, "backend", &attrBuf, NULL); >> } >> >> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h >> index 58b97a2b54..79fd2f1f63 100644 >> --- a/src/conf/domain_conf.h >> +++ b/src/conf/domain_conf.h >> @@ -1067,6 +1067,8 @@ struct _virDomainNetBackend { >> char *vhost; >> /* The following are currently only valid/used when backend >> type='passt' */ >> char *logFile; /* path to logfile used by passt process */ >> + char *hostname; /* hostname of the passt process */ >> + char *fqdn; /* fully qualified domain name of the passt process */ >> }; >> >> struct _virDomainNetPortForwardRange { >> diff --git a/src/conf/schemas/domaincommon.rng >> b/src/conf/schemas/domaincommon.rng >> index 5597d5a66b..f64199ca18 100644 >> --- a/src/conf/schemas/domaincommon.rng >> +++ b/src/conf/schemas/domaincommon.rng >> @@ -3913,6 +3913,12 @@ >> <ref name="absFilePath"/> >> </attribute> >> </optional> >> + <optional> >> + <attribute name="hostname"/> >> + </optional> >> + <optional> >> + <attribute name="fqdn"/> >> + </optional> >> </element> >> </optional> >> <optional> >> diff --git a/src/qemu/qemu_passt.c b/src/qemu/qemu_passt.c >> index fcc34de384..81e5c51f6c 100644 >> --- a/src/qemu/qemu_passt.c >> +++ b/src/qemu/qemu_passt.c >> @@ -229,6 +229,12 @@ qemuPasstStart(virDomainObj *vm, >> if (net->backend.logFile) >> virCommandAddArgList(cmd, "--log-file", net->backend.logFile, >> NULL); >> >> + if (net->backend.hostname) >> + virCommandAddArgList(cmd, "--hostname", net->backend.hostname, >> NULL); >> + >> + if (net->backend.fqdn) >> + virCommandAddArgList(cmd, "--fqdn", net->backend.fqdn, NULL); >> + >> /* Add IP address info */ >> for (i = 0; i < net->guestIP.nips; i++) { >> const virNetDevIPAddr *ip = net->guestIP.ips[i]; >> diff --git a/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml >> b/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml >> index cfe07cc627..77da297936 100644 >> --- a/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml >> +++ b/tests/qemuxmlconfdata/net-user-passt.x86_64-7.2.0.xml >> @@ -50,7 +50,7 @@ >> <range start='443' to='344'/> >> </portForward> >> <model type='rtl8139'/> >> - <backend type='passt' logFile='/var/log/loglaw.blog'/> >> + <backend type='passt' logFile='/var/log/loglaw.blog' >> hostname='hostname1' fqdn='hostname1.test.local'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' >> function='0x0'/> >> </interface> >> <input type='mouse' bus='ps2'/> >> diff --git a/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml >> b/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml >> index d7e0ef5f90..917a9edaa0 100644 >> --- a/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml >> +++ b/tests/qemuxmlconfdata/net-user-passt.x86_64-latest.xml >> @@ -50,7 +50,7 @@ >> <range start='443' to='344'/> >> </portForward> >> <model type='rtl8139'/> >> - <backend type='passt' logFile='/var/log/loglaw.blog'/> >> + <backend type='passt' logFile='/var/log/loglaw.blog' >> hostname='hostname1' fqdn='hostname1.test.local'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' >> function='0x0'/> >> </interface> >> <input type='mouse' bus='ps2'/> >> diff --git a/tests/qemuxmlconfdata/net-user-passt.xml >> b/tests/qemuxmlconfdata/net-user-passt.xml >> index 20c9f50542..80d15de2ed 100644 >> --- a/tests/qemuxmlconfdata/net-user-passt.xml >> +++ b/tests/qemuxmlconfdata/net-user-passt.xml >> @@ -47,7 +47,7 @@ >> <range start='443' to='344'/> >> </portForward> >> <model type='rtl8139'/> >> - <backend type='passt' logFile='/var/log/loglaw.blog'/> >> + <backend type='passt' logFile='/var/log/loglaw.blog' >> hostname='hostname1' fqdn='hostname1.test.local'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' >> function='0x0'/> >> </interface> >> <input type='mouse' bus='ps2'/> >> diff --git a/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml >> b/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml >> index 529aff11f8..5802754c4b 100644 >> --- a/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml >> +++ b/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.xml >> @@ -53,7 +53,7 @@ >> <range start='443' to='344'/> >> </portForward> >> <model type='virtio'/> >> - <backend type='passt' logFile='/var/log/loglaw.blog'/> >> + <backend type='passt' logFile='/var/log/loglaw.blog' >> hostname='hostname1' fqdn='hostname1.test.local'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' >> function='0x0'/> >> </interface> >> <interface type='vhostuser'> >> diff --git a/tests/qemuxmlconfdata/net-vhostuser-passt.xml >> b/tests/qemuxmlconfdata/net-vhostuser-passt.xml >> index 71b845329b..0a37511a0f 100644 >> --- a/tests/qemuxmlconfdata/net-vhostuser-passt.xml >> +++ b/tests/qemuxmlconfdata/net-vhostuser-passt.xml >> @@ -50,7 +50,7 @@ >> <range start='443' to='344'/> >> </portForward> >> <model type='virtio'/> >> - <backend type='passt' logFile='/var/log/loglaw.blog'/> >> + <backend type='passt' logFile='/var/log/loglaw.blog' >> hostname='hostname1' fqdn='hostname1.test.local'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' >> function='0x0'/> >> </interface> >> <interface type='vhostuser'> >> -- >> 2.49.0 >> >> Build libvirt-11.5 with this patch. It works for me. > > Correct the version: v11.4.0-98-g1ee74707bd > -- > Tested-by: Han Han <hhan(a)redhat.com&gt; >