- Devel - libvirt List Archives

Re: [Libvir] [RFC]OpenVZ XML def
by Richard W.M. Jones 05 Jul '07

05 Jul '07

Shuveb Hussain wrote: >> >> Daemon though? Can't the libvirt code just invoke the OpenVZ commands >> directly? > > Yeah, that is very much possible. But if it were a daemon, it could be > a Python daemon, since text processing is much simpler and I don't > have to use the str*( ) funcs in C. What is your comment? I'm a big advocate of using a sane language instead of C, but libvirt is written in C for better or worse. The problem with a separate daemon is management of that daemon. Something needs to start it and stop it, it needs to have sockets with the right permissions and so on. What happens if the process runs and can't find the daemon? What is the path to the socket? etc. etc. At the moment we have two daemons - the qemu daemon (which has two separate functions intertwined), and a remote daemon (necessary, because there's no other way to communicate to a remote machine). One idea would be to have the Python code fork off from the main program and communicate over a pipe. With this, there is no daemon management problem. +----------------+ | Program | | - - - - - - - -| | libvirt | +----------------+ | | fork(2) and pipe(2) | +-------------+ | Python code | +-------------+ But I'm not the person who ultimately decides what would be acceptable in libvirt. You'd need to get general agreement on the best way to do this. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

3 7

[Libvir] [PATCH] virDomainLookup* functions raise VIR_ERR_NO_DOMAIN if the domain doesn't exist
by Richard W.M. Jones 05 Jul '07

05 Jul '07

The patches that I'm going to follow up with change virDomainLookup* functions so that they raise VIR_ERR_NO_DOMAIN where a domain doesn't exist (but there is no other error), else raise some other error where there's an actual error occuring. This will allow wrappers in other languages to distinguish the three cases found / not found / error. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

3 20

[Libvir] [PATCH] Fix xm_internal configCache
by Richard W.M. Jones 04 Jul '07

04 Jul '07

This patch: (1) Fixes inactive domains over remote. The real cause of this error turned out to be that after configCache hash is created, the last refresh date wasn't reset, so a subsequent call to xenXMConfigCacheRefresh might not actually repopulate the cache. This only affects the remote case, because only in the remote case do we have a long running process (libvirtd) which closes and reopens xm_internal.c, so this code had never been exercised before. It also explains why the bug was annoyingly intermittent. If you wait >= 10 seconds during testing, then the cache does get refilled, so the bug is hidden. (2) Adds error messages to xenXMConfigCacheRefresh. (3) As Daniel Veillard suggested, change the obscure !nconnections-- condition to two explicit statements. (4) In xenXMOpen, change the condition from nconnections == 0 to configCache == NULL, to remove the implicit dependency between the two variables. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

2 2

[Libvir] [PATCH] xend 404 errors return VIR_ERR_NO_DOMAIN
by Richard W.M. Jones 04 Jul '07

04 Jul '07

(1) Check for 404 errors from xend and turn them into VIR_ERR_NO_DOMAIN (currently they are VIR_ERR_POST_FAILED). You'll typically see this when you have a handle to a domain, but the underlying domain is shutdown, as in this example: $ python Python 2.4.3 (#1, Dec 11 2006, 11:39:03) [GCC 4.1.1 20061130 (Red Hat 4.1.1-43)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import libvirt >>> conn = libvirt.open ("xen+tls:///") >>> dom = conn.lookupByName ("fc6_6") >>> dom.suspend () 0 >>> dom.resume () 0 #### here, I shut down the domain using 'xm' >>> dom.suspend () libvir: Xen Daemon error : Domain not found: No such domain fc6_6 Traceback (most recent call last): File "<stdin>", line 1, in ? File "/home/rjones/local/lib/python2.4/site-packages/libvirt.py", line 359, in suspend if ret == -1: raise libvirtError ('virDomainSuspend() failed', dom=self) libvirt.libvirtError: virDomainSuspend() failed Domain not found: No such domain fc6_6 (2) There was a case where xend was returning an error, but we didn't translate that into an error return code (-1). I'm sure this is an oversight, and the patch fixes it. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

2 1

[Libvir] [PATCH] Fix callers to virGetDomain and virGetNetwork
by Richard W.M. Jones 04 Jul '07

04 Jul '07

(1) Removes virGetDomainByID. This function was neither used nor exported. (2) virGetDomain sets a virterror connection error whenever anything bad happens (realistically malloc failure is the only thing that can go wrong). Therefore callers do not need to set virterror if the function returns NULL. The patch fixes these callers. (3) Same as (2), for virGetNetwork. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

2 1

[Libvir] Proposal: Python bindings should turn NO_DOMAIN/NO_NETWORK errors in KeyError exceptions
by Richard W.M. Jones 04 Jul '07

04 Jul '07

I propose that we should change the Python bindings so that when the virterror errors VIR_ERR_NO_DOMAIN and VIR_ERR_NO_NETWORK occur in the lookup* functions only, should cause KeyError to be raised. According to: http://docs.python.org/lib/module-exceptions.html "[KeyError is] raised when a mapping (dictionary) key is not found in the set of existing keys." I've already changed the OCaml bindings so that these errors get converted into Not_found exception, which is the "natural" exception for when something is looked up and not found. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

2 2

[Libvir] [PATCH] virNetworkLookup* functions should raise VIR_ERR_NO_NETWORK
by Richard W.M. Jones 04 Jul '07

04 Jul '07

This small patch changes the virNetworkLookup* functions so that they raise VIR_ERR_NO_NETWORK in the case where the network cannot be found (as opposed to some other error). It requires the VIR_ERR_NO_DOMAIN patches (see previous thread) to be applied first, or at least patch #1 from that series. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

2 2

[Libvir] [PATCH] Readd buffer errors & some cleanups
by Richard W.M. Jones 04 Jul '07

04 Jul '07

This readds some error checking of the returns from virBuffer* functions, removes need for is_blank (a _GNU_SOURCE extension), and a couple of other very minor cleanups. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

3 4

[Libvir] PATCH: Fix remote driver to handle network API for local non-QEMU
by Daniel P. Berrange 04 Jul '07

04 Jul '07

The remote_internal.c code is basically a no-op in its remoteNetworkOpen method. This means the remote driver will only handle the networking APIs, if it is also handling the main domain APIs. This works fine if connecting to a remote URI, or if using QEMU URIs, but it does not work if using the test or Xen drivers. To make this work the remoteNetworkOpen method needs to open a connection to the remote daemon IIF the remoteOpen method did not already open one. So the attached patch adds the neccessary logic in remoteNetworkOpen. It also adds code to remoteNetworkClose to make it shutdown& free the connection IIF it was opened by the remoteNetworkOpen method. This is what the extra 'networkOnly' field in the 'struct private_data' is used to check. Second, all of the implementations of virNetwork* APIs in the remote_internal.c driver must use the 'struct private_data *' from networkPrivateData field in virConnectPtr, not the 'privateData' field. This is because the 'privateData' field is probably storing data related to the Xen or Test drivers. Third, this also fixes the qemu_driver.c which incorrectly used the privateData field insteadof the networkPrivateData field for 2 of the networking APIs, and finally makes sure the qemu_driver.c also acccepts the use of qemu:///session APIs for root user. Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

3 5

[Libvir] Proposal: libvirt should remove or rename a save file after a successful restore
by Richard W.M. Jones 03 Jul '07

03 Jul '07

Chris Lalancette found this problem: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=246105 <quote> Once an "xm restore" has successfully completed, the -save file that it came from should really be deleted. Restoring a domain a second time from the same save file will result in disk corruption; the kernel VM state (in the saved file) will be in an inconsistent state with respect to what is actually on disk (in the domain disk file). The only valid use I can see for the -save file after a restore is possibly for some crash analysis, but even that could be worked around by renaming the save file after a success. In particular, I just ran into this situation (and I'm worried customers might do the same): [and then he goes on to describe a scenario in which you can commonly hit this situation] </quote> So the obvious and simple solution, it seems to me, is just to change libvirt.c:virDomainRestore so that if the driver underneath it returns from the restore without error, then we either remove or rename the restore file. It's a trivial patch -- what do people think? My thoughts: * Removing the file might seem quite abrupt/unexpected, and there is the possibility of data loss. * You have to rename the file as a hidden file (dotfile) in order for xendomains to ignore it. However these files are big and having large, hidden files which build up in number over time sounds like it could be a bad thing. * This might be considered a significant behaviour change. * It's easier to handle this for the remote case if we make the change inside libvirt, rather than in virsh etc. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

3 2