Influence guest from host

[jac2703]

Hi guys,

At a high level, I am trying to get my guest to execute a particular script. The catch, however, is that I want to issue this command from the host.

Ideally, on my host I would like to say something like some-qemu-command runonguest vmid path/to/script but I fully expect this to be impossible. I would be happy with having a daemon running on the guest, constantly polling for something to change which would be done from the host. Does anyone have any ideas?

I should qualify a few points:

• There are a number of different scripts I would like to run, depending on the instruction from the host (lets say < 50 different scripts).
• The guest is Windows Server 2008 R2.

Any help, or thoughts would be most appreciated.

James.

 

[dietmar]

I guess you need to run the 'qemu guest agent' inside the guest to do such thing. The source is inside qemu git:

http://git.qemu.org/?p=qemu.git;a=tree;f=qga;

But we currently have no support for that (but panned for 3.0 release).

 

[half_life]

Hi guys,

At a high level, I am trying to get my guest to execute a particular script. The catch, however, is that I want to issue this command from the host.

Ideally, on my host I would like to say something like some-qemu-command runonguest vmid path/to/script but I fully expect this to be impossible. I would be happy with having a daemon running on the guest, constantly polling for something to change which would be done from the host. Does anyone have any ideas?

I should qualify a few points:

• There are a number of different scripts I would like to run, depending on the instruction from the host (lets say < 50 different scripts).
• The guest is Windows Server 2008 R2.

Any help, or thoughts would be most appreciated.

James.

Several things come to mind. Have you thought about using CIFS shares to:
create a semaphore (if file exists do this command then delete the file)
create a drop file (if file exists open it and do what it says then delete it)

look into running your scripts via a service then use net rpc commands from the host

Not really complete "cut and paste" solutions but they should get you going in the right direction.

 

[half_life]

Several things come to mind. Have you thought about using CIFS shares to:
create a semaphore (if file exists do this command then delete the file)
create a drop file (if file exists open it and do what it says then delete it)

look into running your scripts via a service then use net rpc commands from the host

Not really complete "cut and paste" solutions but they should get you going in the right direction.

 

[dietmar]

Well, you can also simply use ssh.

 

[half_life]

Well, you can also simply use ssh.

<smacks forehead> Well there is that too </smacks forehead>

 

[jac2703]

Hi Guys,

Thanks for the replys.

I am going to take the route of using a NFS/ apache server to drive the scripts. A script on each guest will poll 'something' (NFS/ Apache/ etc.) and action as required.

Just a note: We are not able to use a guest agent as the VM needs to be portable to other Hypervisors such as VirtualBox. My experience is that guest agents can massively complicate this.