Re: block-nbd script and example config

[Anthony Liguori <aliguori@us.ibm.com>]

Ian Pratt wrote:

>Let's think a little about what we'd like this to look like. 
>
>Taking a similar approach to network devices, we'd end up with something
>that looks like this:
>
>  disks = [ 'export=phy:/dev/sda1, target=/dev/sda1, options=rw',
>            'export=phy:/dev/vg/my_usr, target=/dev/sdb1, options=ro' ]
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>
Yup.  Here's another example:

disks = [ 'export=file:/home/anthony/images/Fedora Core 4.img, 
target=/dev/sda1, options=rw',

This is going to become difficult to parse (we could split with ',' here 
but then what if we have commas in files).  We could support an escaping 
mechanism but then it would require triple escapes like:

disks = [ 'export=file:/home/anthony/image/Fedora Core 4\\\, x86-64.img, 
target=/dev/sda1, options=rw' ]

Or regular expression syntax:

disks = [ r'export=file:/home/anthony/image/Fedora Core 4\, x86-64.img, 
target=/dev/sda1, options=rw' ]

>I'm wandering whether the following although slightly ugly might be
>better from a python POV (we'd change network devices acordingly too:
>
>  disks = [ { 'export':'phy:/dev/sda1', 'target':'/dev/sda1',
>'options':'rw' },
>            { 'export':'phy:/dev/vg/my_usr', 'target':'/dev/sdb1',
>'options':'ro' } ]
>  
>
I thought of this too.  I think it's just too much to ask from users 
though.  If you know python, it's understandable, but if you don't, I 
think it reads like gibberish.

>Is this just too ugly and would we be better off going with my first
>proposal? Or should we just leave things alone for 3.0?
>  
>
Yeah, perhaps we should just leave things alone for 3.0.  We can revisit 
when someone comes up with a clever syntax that solves the above problems.

Regards,

Anthony Liguori

>Ian
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