The code is still in rough shape, but while we're on the topic of guest agents
I wanted to put out a working example of how exec functionality can be added
to qemu-ga to provide a mechansim for building arbitrarilly high-level
interfaces.
The hope is that by allowing qemu-ga to execute commands in the guest, paired
with file read/write access, we can instrument a guest "on the fly" to support
any type of hyperviser functionality, and do so without dramatically enlarging
the role qemu-ga plays as a small, QEMU-specific agent that is tightly
integrated with QEMU/QMP/libvirt.
These patches add the following interfaces:
guest-file-open-pipe
guest-exec
guest-exec-status
The guest-file-open-pipe interface is analagous to the existing guest-file-open
interface (it might be best to roll it into it actually): it returns a handle
that can be handled via the existing guest-file-{read,write,flush,close}
interface. Internally it creates a FIFO pair that we can use to associate
handles to the stdin/stdout/stderr of a guest-exec spawned process. We can also
also use them to redirect output into other processes, giving us the basic
tools to build a basic shell (or a full-blown one if we add TTY support) using
a single qemu-ga.
Theoretically we can even deploy other agents, including session-level agents,
and communicate with them via these same handles. Thus, ovirt could deploy and
run an agent via qemu-ga, Spice could deploy vdagent, etc. Since the interface
is somewhat tedious, I'm working on a wrapper script to try out some of
these scenarios, but a basic use case using the raw QMP interface is included
below.
Any thoughts/comments on this approach are appreciated.
EXAMPLE USAGE (execute `top -b -n1`):
{'execute': 'guest-file-open-pipe'}
{'return': 6}
{'execute': 'guest-exec', \
'arguments': {'detach': True, \
'handle_stdout': 6, \
'params': [{'param': '-b'}, \
{'param': '-n1'}], \
'path': 'top'}}
{'return': {'exit-code': 0, \
'exited': False, \
'handle_stderr': -1, \
'handle_stdin': -1, \
'handle_stdout': 6, \
'pid': 14267}}
{'execute': 'guest-file-read', \
'arguments': {'count': 65536, \
'handle': 6}}
{'return': {'buf-b64': '', \
'count': 0, \
'eof': False}}
{'execute': 'guest-file-read', \
'arguments': {'count': 65536, \
'handle': 6}}
{'return': {'buf-b64': 'dG9wIC0gMjI6N...', \
'count': 11064, \
'eof': True}}
/*
top - 22:41:49 up 1 day, 4:30, 3 users, load average: 0.00, 0.00, 0.00
Tasks: 114 total, 1 running, 113 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.2%us, 0.2%sy, 0.0%ni, 99.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 504848k total, 445664k used, 59184k free, 49100k buffers
Swap: 323580k total, 224k used, 323356k free, 256392k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
14267 root 20 0 19272 1248 924 R 2 0.2 0:00.02 top
1 root 20 0 24008 2048 1280 S 0 0.4 0:00.85 init
2 root 20 0 0 0 0 S 0 0.0 0:00.30 kthreadd
3 root 20 0 0 0 0 S 0 0.0 0:01.09 ksoftirqd/0
...
*/
{'execute': 'guest-exec-status', \
'arguments': {'pid': 14267}}
{'return': {'exit-code': 0, \
'exited': True, \
'handle_stderr': -1, \
'handle_stdin': -1, \
'handle_stdout': 6, \
'pid': 14267}}
{'execute': 'guest-file-close'} \
'arguments': {'handle': 6}}
{'return': {}}
Michael Roth (2):
guest agent: add guest-file-open-pipe
guest agent: add guest-exec and guest-exec-status interfaces
qapi-schema-guest.json | 79 +++++++-
qga/guest-agent-commands.c | 478 +++++++++++++++++++++++++++++++++++++++++---
2 files changed, 531 insertions(+), 26 deletions(-)
--
1.7.4.1
