Bug 1286829

Summary:	fedmsg-tail "hangs" when host cannot be resolved
Product:	[Fedora] Fedora	Reporter:	Zbigniew Jędrzejewski-Szmek <zbyszek>
Component:	fedmsg	Assignee:	Ralph Bean <rbean>
Status:	CLOSED NOTABUG	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	23	CC:	lmacken, rbean
Target Milestone:	---
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Fixed In Version:		Doc Type:	Bug Fix
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Clone Of:		Environment:
Last Closed:	2016-03-17 14:59:43 UTC	Type:	Bug
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description Zbigniew Jędrzejewski-Szmek 2015-11-30 20:36:13 UTC

Description of problem:
$ fedmsg-tail --pretty
[2015-11-30 15:21:42][    fedmsg WARNING] Couldn't resolve 'hub.fedoraproject.org'
^C()

If the host cannot be resolved, continuing doesn't seem to make much sense. Should exit with an error.

Comment 1 Ralph Bean 2016-03-17 14:55:46 UTC

Good idea, yes.

Comment 2 Ralph Bean 2016-03-17 14:59:43 UTC

Actually, on second thought - take a look at the code here:  https://github.com/fedora-infra/fedmsg/blob/develop/fedmsg/core.py#L359-L364

A fedmsg client can (and usually does) connect to many message producing endpoints.  For a Fedora end-user, you are typically only subscribed to one:  the Fedora Infrastructure outbound gateway at hub.fedoraproject.org:9940.  But you could also be subscribed to debian's endpoint, or others.  Internally in Fedora Infrastructure, our message consumers are connected to hundreds of message producing endpoints.

If *one* of those endpoints is not resolvable for some reason, should the consumer crash?  fedmsg's design suggests "no".  One of our main goals is to be able to fail graceful in the face of partial network outages, so things can continue to operate "as best they can".  That's why there's a warning there, and not an error.

Thanks for the report!  I'm going to close as NOTABUG.  Feel free to take it up on the upstream fedmsg issue tracker if you like and we can debate it more :)

Comment 3 Zbigniew Jędrzejewski-Szmek 2016-03-17 15:08:17 UTC

It could fail if *all* endpoints failed (in particular in this case all==one).

But the whole issue is a bit of an edge case, so I'm not going to open a bug upstream.