[CRIU] [PATCH p.haul 2/2] p.haul: create Virtuozzo specific dump images during final dump

[Nikita Spiridonov]

On Mon, 2016-05-16 at 21:22 +0300, Pavel Emelyanov wrote:
> On 05/14/2016 05:48 PM, Nikita Spiridonov wrote:
> > For Virtuozzo containers vzctl create addtional images during local
> > dump of the container - vz_clock_bootbased.img,
> > vz_clock_monotonic.img, vz_aio_max_nr.img and vz_core_pattern.img.
> > Need to duplicate this logic in vz module of phaul since we use
> > "vzctl restore" for final restore and it rely on this additional
> > images.
> > 
> > Signed-off-by: Nikita Spiridonov <nspiridonov at virtuozzo.com>
> > ---
> >  phaul/p_haul_vz.py |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 48 insertions(+), 0 deletions(-)
> > 
> > diff --git a/phaul/p_haul_vz.py b/phaul/p_haul_vz.py
> > index 602bd57..3609f14 100644
> > --- a/phaul/p_haul_vz.py
> > +++ b/phaul/p_haul_vz.py
> > @@ -15,6 +15,8 @@ import pycriu.rpc
> >  vz_global_conf = "/etc/vz/vz.conf"
> >  vz_conf_dir = "/etc/vz/conf/"
> >  vzctl_bin = "vzctl"
> > +cgget_bin = "cgget"
> > +cgexec_bin = "cgexec"
> >  
> >  
> >  vz_cgroup_mount_map = {
> > @@ -150,7 +152,53 @@ class p_haul_type:
> >  		pass
> >  
> >  	def final_dump(self, pid, img, ccon, fs):
> > +		"""Perform Virtuozzo-specific final dump"""
> > +		self.__pre_final_dump(img)
> >  		criu_cr.criu_dump(self, pid, img, ccon, fs)
> > +		self.__post_final_dump(img)
> > +
> > +	def __pre_final_dump(self, img):
> > +		"""Create extra images before final dump"""
> > +		extra_images = (
> > +			("vz_clock_bootbased.img", "ve.clock_bootbased"),
> > +			("vz_clock_monotonic.img", "ve.clock_monotonic"),
> > +			("vz_aio_max_nr.img", "ve.aio_max_nr"))
> 
> Less images is better. Can all this stuff be saved in one file?

We can, but it will complicate logic considerably. Entire patch
duplicates libvzctl logic of local dump/restore actually. I think if
such approach suitable there we can just dup it for now.

> 
> > +		for image_name, var_name in extra_images:
> > +			self.__create_cgget_extra_image(img, image_name, var_name)
> > +
> > +	def __post_final_dump(self, img):
> > +		"""Create extra images after final dump"""
> > +		extra_images = (
> > +			("vz_core_pattern.img", ["cat", "/proc/sys/kernel/core_pattern"]),)
> > +		for image_name, exec_args in extra_images:
> > +			self.__create_cgexec_extra_image(img, image_name, exec_args)
> > +
> > +	def __create_cgget_extra_image(self, img, image_name, var_name):
> > +		"""Create extra image using cgget output"""
> > +		proc = subprocess.Popen(
> > +			[cgget_bin, "-n", "-v", "-r", var_name, self._ctid],
> > +			stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
> > +		image_data = proc.communicate()[0]
> 
> Less exec-s is better. Can we save this stuff with one call?

We can replace cgget with manual reads from cgroup vfs. I don't know
suitable alternative for cgexec. Such change needed?

> 
> > +		if proc.returncode == 0:
> > +			self.__create_extra_image(img, image_name, image_data)
> > +		else:
> > +			logging.warning("cgget failed to create %s", image_name)
> > +
> > +	def __create_cgexec_extra_image(self, img, image_name, exec_args):
> > +		"""Create extra image using cgexec output"""
> > +		proc = subprocess.Popen(
> > +			[cgexec_bin, "-g", "ve:{0}".format(self._ctid)] + exec_args,
> > +			stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
> > +		image_data = proc.communicate()[0]
> > +		if proc.returncode == 0:
> > +			self.__create_extra_image(img, image_name, image_data)
> > +		else:
> > +			logging.warning("cgexec failed to create %s", image_name)
> > +
> > +	def __create_extra_image(self, img, image_name, image_data):
> > +		image_path = os.path.join(img.image_dir(), image_name)
> > +		with open(image_path, "w") as f:
> > +			f.write(image_data)
> >  
> >  	def final_restore(self, img, connection):
> >  		"""Perform Virtuozzo-specific final restore"""
> > 
>