[libvirt] [PATCH v4 1/1] migration: add support for migrateURI configuration

[chen.fan.fnst at cn.fujitsu.com]

Hi,
    Firstly thanks for your attention. 

On Thu, 2014-05-15 at 11:50 +0200, Jiri Denemark wrote: 
> On Wed, May 14, 2014 at 15:18:09 +0800, Chen Fan wrote:
> > For now, we set the migration URI via command line '--migrate_uri' or
> > construct the URI by looking up the dest host's hostname which could be
> > solved by DNS automatically.
> > 
> > But in cases the dest host have two or more NICs to reach, we may need to
> > send the migration data over a specific NIC which is different from the
> > automatically resloved one for some reason like performance, security, etc.
> > thus we must explicitly specify the migrateuri in command line everytime,
> > but it is too troublesome if there are many such hosts(and don't forget
> > virt-manager).
> > 
> > This patches add a configuration file option on dest host to save the
> > default migrate uri which explicitly specify which of this host's
> > addresses is used for transferring data, thus user doesn't boring
> > to specify it in command line everytime.
> > 
> > Signed-off-by: Chen Fan <chen.fan.fnst at cn.fujitsu.com>
> > ---
> > 
> > v3-v4: move up the default uri_in setting to
> >        qemuDomainMigratePrepare3Params()
> > 
> >  src/qemu/qemu.conf     | 6 +++++-
> >  src/qemu/qemu_conf.c   | 1 +
> >  src/qemu/qemu_conf.h   | 1 +
> >  src/qemu/qemu_driver.c | 2 +-
> >  4 files changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
> > index f0e802f..6b443d0 100644
> > --- a/src/qemu/qemu.conf
> > +++ b/src/qemu/qemu.conf
> > @@ -449,7 +449,11 @@
> >  #
> >  #seccomp_sandbox = 1
> >  
> > -
> > +# Override the migration URI for specifying one of host's IP addresses
> > +# to transfer the migration data stream.
> > +# Defaults to hostname, both IPv4 and IPv6 addresses are accepted.
> > +#
> > +#migrate_uri = "tcp://192.168.0.1"
> >  
> >  # Override the listen address for all incoming migrations. Defaults to
> >  # 0.0.0.0, or :: if both host and qemu are capable of IPv6.
> 
> The more I think about this the more I incline to a slightly different
> approach. Rather than providing a way to override migration URI, we
> could just provide an option in libvirtd.conf to override what
> virGetHostname returns. That is, the option (naturally called hostname)
> would tell libvirt to use the configured hostname (which might even be
> just an IP address) instead of trying to detect it.
If I understand correctly. you prefer using a hostname(or IP address) 
option in libvirtd.conf to configuring a default migration URI in
qemu.conf, right? do you want to affect the all virGetHostname()
returns? I'm afraid I can't see any benefit to the goal, could you tell
me that?

Thanks,
Chen


> 
> > diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> > index 198ee2f..43361dc 100644
> > --- a/src/qemu/qemu_conf.c
> > +++ b/src/qemu/qemu_conf.c
> > @@ -574,6 +574,7 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
> >  
> >      GET_VALUE_LONG("seccomp_sandbox", cfg->seccompSandbox);
> >  
> > +    GET_VALUE_STR("migrate_uri", cfg->migrateUri);
> >      GET_VALUE_STR("migration_address", cfg->migrationAddress);
> >  
> >      ret = 0;
> > diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
> > index a36ea63..f99c56e 100644
> > --- a/src/qemu/qemu_conf.h
> > +++ b/src/qemu/qemu_conf.h
> > @@ -163,6 +163,7 @@ struct _virQEMUDriverConfig {
> >  
> >      int seccompSandbox;
> >  
> > +    char *migrateUri;
> >      /* The default for -incoming */
> >      char *migrationAddress;
> >      int migrationPortMin;
> > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> > index fca1a91..56c24b5 100644
> > --- a/src/qemu/qemu_driver.c
> > +++ b/src/qemu/qemu_driver.c
> > @@ -10888,7 +10888,7 @@ qemuDomainMigratePrepare3Params(virConnectPtr dconn,
> >      virDomainDefPtr def = NULL;
> >      const char *dom_xml = NULL;
> >      const char *dname = NULL;
> > -    const char *uri_in = NULL;
> > +    const char *uri_in = cfg->migrateUri;
> >      const char *listenAddress = cfg->migrationAddress;
> >      char *origname = NULL;
> >      int ret = -1;
> 
> And in any case, the change you made between v3 and v4 is wrong, since
> now you are only change one entry point to the Prepare phase while
> changing qemuMigrationPrepareDirect makes this work for all APIs and
> migration protocol versions.
Oh, you are right. thanks.

Chen 
> 
> Jirka