On Fri, Dec 17, 2021 at 4:03 PM Marco Dickert - evolver group <[email protected]> wrote: > > On 2021-12-17 15:25:31, Batanun B wrote: > > Thanks. I have thought about that too. But I think we might want to include > > non-error transactions as well. I mean, with the problems this post is about > > we want to see when the cached version of the start page was generated and > > when it was last served from cache successfully. But maybe we could have a > > permanent logging just for the start page, regardless of http status. That > > should hopefully reduce the logging intensity enough so that logging to disk > > isn't effecting the Varnish performance. > > Well, it depends on the performance of your storage and the amount of req/sec > on > the front page, but these logs can get very huge very quickly. I'd suggest to > determine the correct delivery of the front page via an external monitoring > (e.g. icinga2 or a simple script). As far as I understand, you don't need to > know the exact request, but more of a rough point in time of when the requests > start failing. So a monitoring script which curls every minute should be > sufficient and causes a lot less trouble. > > > One thing though... If you log all "status: 500+" transactions to disk, > > isn't > > there a risk that your logging might exacerbate a situation where your site > > is > > overwhelmed with traffic? Where a large load causes your backends to start > > failing, and that triggers intense logging of those erroneous transactions > > which might reduce the performance of Varnish, causing more timeouts etc > > which > > cause more logging and so on... > > Indeed there is a risk of self-reinforcing effects, but it didn't happen yet. > We > also do not plan to logging 500s forever, but only till our problem is solved, > which is an error in varnishs memory handling. At the moment, our most > concerning 500s are caused by varnish itself, stating "Could not get storage", > when the configured memory limit is reached.
If you get a surge of 5XX responses from either Varnish or the backend, you can also rate-limit logs to the disk: https://varnish-cache.org/docs/6.0/reference/varnishlog.html See the -R option. Cheers, Dridi _______________________________________________ varnish-misc mailing list [email protected] https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
