[Testing] ssh-controlled testbeds with dsh

[Mel Chua]

Following up on Gary's emails and Michael's suggestion from last week, I 
was playing around this morning with...

http://wiki.laptop.org/go/Dsh

...and life looks pretty glorious.

Why is this cool? Well, say you wanted to run the ps command on all the 
machines in your /etc/dsh/machines file, which looks like this...

olpc at 18.85.49.113
olpc at 18.85.49.114

All you have to do is this:

mchua at tumtum-tree:~$ dsh -Mac ps

And you'll get this.

olpc at 18.85.49.113:  PID TTY          TIME CMD
olpc at 18.85.49.113: 1166 ?        00:00:00 startx
olpc at 18.85.49.113: 1185 ?        00:00:00 xinit
olpc at 18.85.49.113: 1211 ?        00:00:02 ck-xinit-sessio
<...more entries from 18.85.49.113 go here>
olpc at 18.85.49.114:  PID TTY          TIME CMD
olpc at 18.85.49.114: 1549 ?        00:00:00 startx
olpc at 18.85.49.114: 1566 ?        00:00:00 xinit
olpc at 18.85.49.114: 1577 ?        00:01:31 python
<...more entries from 18.85.49.114 go here>

To answer Gary's previous question, we're trying to do the third option 
- option 2 as a special case of option 1. The example on the dsh 
wikipage is a good simple example (running ps).

>
> 1). Want to run some admin script on every XO. Perhaps you want to 
> wipe the datastore and reboot, perhaps you want to trigger suspend and 
> use administration ping to wake them up again repeatedly, etc.
>
> 2). Want to collect a set of data from every XO and look for 
> anomalies/failures. This could be lists of buddies each is currently 
> seeing, or AP each is seeing, cpu loads, free memory, dropped packets, 
> packet collisions, etc. 

> You could see option 2 as a specific case of option 1, where you write 
> a nice batch that collects and cleanly reformats all the spurious 
> outputs you get from the various tools.

-- 
Mel Chua
QA/Support Engineer
mel at laptop.org