VOSI availability

[Theresa Dower]

FWIW the MAST TAP services basically handle /availability in nearly the same way as CADC's -- with some load balancing that obfuscates what we're checking behind the scenes, but pings down to the database. We use this for externally hosted site monitoring.  With a mind to operations, if the issue here is lack of takeup combined with fuzziness on what it really means per provider, I'd rather see it marked down to optional with a note that it might not be meaningful for mirrors, etc, and otherwise leave the schema alone.


Cheers,

--Theresa

________________________________
From: dal-bounces at ivoa.net <dal-bounces at ivoa.net> on behalf of Brian Major <major.brian at gmail.com>
Sent: Thursday, July 22, 2021 7:28:38 PM
To: <dal at ivoa.net>; Markus Demleitner
Subject: Re: VOSI availability

External Email - Use Caution
Hi Markus,

On Tue, Jun 15, 2021 at 4:52 AM Markus Demleitner <msdemlei at ari.uni-heidelberg.de<mailto:msdemlei at ari.uni-heidelberg.de>> wrote:
...

I'm told CADC is using availability in internal processes -- but for
that, we don't need to burden our standards, and we don't need to
accept the disgrace that 10 years into VOSI's declaration that
all services MUST implement VOSI a10y, only about 400 out of about
23000 actually do (and the rest are thus in violation of a REC).


Yes, all of our services (IVOA or not) implement /availability.  They each do their own specific health check on resources on which they depend.  We've also added an optional parameter 'detail=min' which will do nothing, but is handy as a 'ping' type probe to the service.  The calls are made by nagios and our ops team gets alerts on failed calls or when they return false.  We don't currently use mirrors, but we have multiple instances of services behind load balancers.  Calls to /availability could hit any of those instances, so it's not particularly informative about server health, but it is good for those downstream dependency checks.

So, it's handy and useful to us, but we don't require it in any sort of interoperable way.  I'm sure this has already been considered, but I think its value (if any) would lie with the operations interest group.

Cheers,
Brian
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