[chef] Re: Re: Save from recipe data to chef server

[Seth Falcon < >]

 writes:
> It is 'possible' to do this with Chef, though I can't guarantee Chef will
> do it well.  This sort of coordination is not what Chef excels at, and if
> it is really important I would recommend using something better at
> coordination, like Zookeeper. That said, here are some possible Chef
> solutions:

+1 on the caveats. Chef Server doesn't provide orchestration primitives
at this time.

It is something that we discuss adding and it always helps to examples
of what would be useful.

> 3. Databags are another option.  These have many of the same caveats as
> using Node attributes as it is hard to guarantee and atomic update.  The
> most likely failure scenario is two nodes read that no one has the lock and
> both try to add it.  Since databags always overwrite with the latest data,
> they will both 'write' the lock and proceed to cheerfully destroy
> data.

While it really is not a good idea, if you are going go down this route,
I'd recommend using the presence/absence of a data bag (not data bag
item).

    api.post("data", {:name => "lock1"})

This will only succeed if there is not already such a data bag (returns
409 if a bag named lock1 already exists). Top-level data bags are about
as light weight as you can get and get you closest to the atomic CAS
thing.

+ seth

-- 
Seth Falcon | Development Lead | Opscode | @sfalcon