At the Xen Hackathon I learnt that libxl provides an API which
can serialize a libxl_domain_config instance to a JSON document.
This is exactly what we need for testing the XML -> libxl_domain_config
conversion process, so I spent the afternoon trying to get such a test
working. The result is that we can now just add pairs of XML, JSON
files to libvirt to test handling of new config features.
I hit a couple of small issues with libxl, which I worked around, when
writing this test which I why I'm copying xen-devel
- libxl_ctx_alloc() will call xs_daemon_open and xc_interface_open,
and stat /var/run/xenstored.pid to see if Xen is actually running.
This fails when run on non-Xen hosts (and also possibly if run
unprivileged).
I used an evil LD_PRELOAD hack to stub out xs_daemon_open and
xc_interface_open to return (void*)0x1, and also turn
xc_interface_close and xs_daemon_close to no-ops, and make
stat() always return success for xenstored.pid.
This works (evidenced by the fact that if something was needing
these xs/xc handles they would have crashed referencing 0x1),
but at the same time it might be an idea to have an officially
supported "non live" mode for libxl_ctx_alloc() turned on by a
flag of some sort.
- The libxl_json.h header file is relying on conditionals that
are only set by Xen's build process
eg HAVE_YAJL_YAJL_VERSION_H
I hacked around this, but it is a little dirty too. libvirt
already links to libyajl for the QEMU driver, but we don't
really need the raw YAJL objects. It'd be nice to have a
char * libxl_domain_config_as_json(libxl_domain_config *p)
as a higher level wrapper around libxl_domain_config_gen_json
avoiding the pain of dealing with YAJL's different APIs.
Ian J mentioned to me that he thought there was already such a
method, but AFAICT, the only such code is in the 'xl' command
line tool itself (xl_cmdimpl.c - printf_info_one_json)
A few further ideas that could be done as a followup
- Make virConnectDomainXMLToNative accept 'xl-json" as a
data format, so you can feed in a libvirt XML and get back
out a JSON document. This could be a useful debugging tool
for Xen developers trying to identify bugs in libvirt.
- Write out the JSON document to /var/log/libvirt/libxl/$GUEST.log
whenever starting a guest. Again this would be a useful debugging
aid to Xen developers / support people trying to identify why a
guest might be mis-behaving
Regards,
Daniel
Daniel P. Berrange (5):
Don't pass virDomainObjPtr to libxlBuildDomainConfig
Don't pass libxlDriverPrivatePtr into libxlBuildDomainConfig
libxl: Move virDomainXMLOptionNew into libxlCreateXMLConf
Add more test suite mock helpers
Add a test suite for libxl option generator
src/libxl/libxl_conf.c | 38 +++---
src/libxl/libxl_conf.h | 10 +-
src/libxl/libxl_domain.c | 7 +-
src/libxl/libxl_driver.c | 4 +-
tests/Makefile.am | 25 +++-
tests/libxlxml2jsondata/minimal.json | 172 +++++++++++++++++++++++++++
tests/libxlxml2jsondata/minimal.xml | 36 ++++++
tests/libxlxml2jsontest.c | 219 +++++++++++++++++++++++++++++++++++
tests/virfirewalltest.c | 4 +-
tests/virmock.h | 54 ++++++---
tests/virmocklibxl.c | 87 ++++++++++++++
tests/virsystemdtest.c | 4 +-
12 files changed, 617 insertions(+), 43 deletions(-)
create mode 100644 tests/libxlxml2jsondata/minimal.json
create mode 100644 tests/libxlxml2jsondata/minimal.xml
create mode 100644 tests/libxlxml2jsontest.c
create mode 100644 tests/virmocklibxl.c
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1.9.3