Seeing a strange behavior with <cfimage> and...
# cfml-generalm
Mike Greider
04/15/2024, 2:01 PMSeeing a strange behavior with <cfimage> and a load balanced site.
Mike Greider
04/15/2024, 2:01 PMIt's load balanced through CloudFlare with two CF servers. On one of the pages, there is a <cfimage> with "writeToBrowser". It's putting from a non-web accessible file share and displaying the image on a form. When I go to either server independently, everything works as expected. When I go through the load balancer, it mostly always works. But there are sporadic 404 on the rendered _cfimg. I'm not 100% sure where to go to troubleshoot this. Nothing obvious in the CF or IIS logs.
Mike Greider
04/15/2024, 2:01 PMIndividual servers one and two, both fine
Mike Greider
04/15/2024, 2:01 PMimage.png
Mike Greider
04/15/2024, 2:02 PMThrough CloudFlare on the LB
Mike Greider
04/15/2024, 2:02 PMSame image in all three requests.
Mike Greider
04/15/2024, 2:02 PMAny thoughts as to where to track this down and better troubleshoot?
Mike Greider
04/15/2024, 2:09 PMAlso, when I turn off either of the origin at CloudFlare so that it's still going through the load balancer, but essentially just going to one server ... the issue goes away too.
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dswitzer
04/15/2024, 2:13 PMImages generated dynamically have a short shelf live. CF will purge the files, which most likely explains why trying to refresh the image is returning 404s.
m
Mike Greider
04/15/2024, 2:15 PMRoger that. The 404s are all in the same request. Identical requests on individuals servers are coming back 200s, but through the LB, 400s
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foundeo
04/15/2024, 2:16 PM
The /CFFileServlet writes the image to disk temporarily, so the actual file will only be on one of the two servers
m
Mike Greider
04/15/2024, 2:16 PMIs it a second http request for <cfimage>?
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foundeo
04/15/2024, 2:18 PM
I think it might be, take a look at the Response tab on the cfm that has the cfimage tag in developer tools
m
Mike Greider
04/15/2024, 2:18 PMAs I'm typing that out, I realize what you both are saying and get it. Of course, it's a separate http request for the <img>. And obviously, that could be on the other local drive
Mike Greider
04/15/2024, 2:20 PM<cfimage> with writeToBrowser won't ever really work consistently in a LB unless you have something like sticky sessions enabled.
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foundeo
04/15/2024, 2:21 PM
you might need to write to a temp file, then serve it yourself with cfcontent - that should work fine in a LB env
foundeo
04/15/2024, 2:21 PM
I think cfimage writeToBrowser is either just outputting an HTML <img> tag or redirecting to the /CFFileServlet either way it is causing a second http request
m
Mike Greider
04/15/2024, 2:22 PMThat's exactly what I'll do. Thank you for the sanity check.
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