if-modified-since not functioning as expected in Azure Web App

0
votes

I have a angular 1.x SPA app built with ASP Web API hosted in Azure as a Web App. When I deploy new code browsers such as Chrome (not edge or IE) fail to get the new code based on If-modified-since or ETAG. The current workaround is to have users do a CTRL + F5 to force a download. There are some differences in the request headers between Edge and Chrome that may explain this but I am not very familiar with the cache control mechanisms within HTTP.

My main question is this an expected behavior and I need to deliberately detect this in client side code and force a refresh or is this something IIS is expected to handle by default? Secondarily is this something I can solve through changes to web.config?

Edge

  • Accept: application/javascript, /; q=0.8
  • Accept-Encoding: gzip, deflate
  • Accept-Language: en-US
  • Connection: Keep-Alive
  • Cookie: ai_user=T9jXc|2016-08-08T05:44:23.776Z; ai_session=2GcvV|1470765398272|1470765399564
  • Host: app.somehost.com
  • If-Modified-Since: Mon, 08 Aug 2016 16:34:46 GMT
  • If-None-Match: "0172c692f1d11:0"
  • Referer: https://app.somehost.com/
  • User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.79 Safari/537.36 Edge/14.14393

Chrome

  • Accept:/
  • Accept-Encoding:gzip, deflate, sdch, br
  • Accept-Language:en-US,en;q=0.8
  • Cache-Control:max-age=0
  • Connection:keep-alive
  • Cookie:ai_user=WXgAN|2016-08-09T16:28:50.251Z; ai_session=nV7TD|1470765376324|1470765376960
  • Host:app.somehost.com
  • If-Modified-Since:Mon, 08 Aug 2016 16:34:46 GMT
  • If-None-Match:"0172c692f1d11:0"
  • Referer:https://app.somehost.com/
  • User-Agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36
1
asp.netangularjsazureiisazure-web-app-service
Hi Smith, is your application a pure angular SPA or an asp.net application with the angular SPA as the front end client. Or could you tell us how to reproduce your issue? – Gary Liu
Is a SPA app that uses ASP .Net to serve up static content. No RAZOR views or CSHTML except for the top level page. – Micah Smith
The high level repro steps are to 1) deploy the site to azure. 2) visit site with chrome. 3) deploy updated JS file such as a angular controller. 4) re-visit page and what for HTTP 304. To get down to more specific steps I'll need to uncover more about the root cause. One possibly interesting aspect is that the content in question is being requested as part of a bundle but bundle optimizations are currently off. I don't know if that would impact this issue. – Micah Smith

1 Answers

0
votes

The issue was resolved by optimizing bundles. I had optimizations off as it was breaking dependencies that didn't not support minification. To fix the issue I removed the offending .js files from the bundles and references them directly. Then enabled optimizations in BundleConfig.cs

BundleTable.EnableOptimizations = true