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https://issues.apache.org/jira/browse/TS-2961?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alan M. Carroll updated TS-2961:
--------------------------------
Fix Version/s: (was: 5.1.0)
5.2.0
> Expires: 0 and Expires: past date being temporarily cached
> ----------------------------------------------------------
>
> Key: TS-2961
> URL: https://issues.apache.org/jira/browse/TS-2961
> Project: Traffic Server
> Issue Type: Bug
> Affects Versions: 5.0.1
> Reporter: Nick Muerdter
> Priority: Minor
> Fix For: 5.2.0
>
>
> While doing some integration testing with TrafficServer, I noticed some
> seemingly odd behavior: If my origin server returns "{{Expires: 0}}" or
> "{{Expires: SOME_PAST_DATE}}" headers, TrafficServer appears to cache these
> responses for about 1 second. This would seem to run counter to the
> [documentation|https://docs.trafficserver.apache.org/en/latest/admin/http-proxy-caching.en.html?highlight=expires#origin-server-directives]:
> {quote}
> By default, Traffic Server does not cache objects with the following response
> headers:
> - Expires: header with value of 0 (zero) or a past date
> {quote}
> I was able to reproduce this with a stock TrafficServer 5.0.1 installation
> pointing at an origin server that returns a random, unique output on each
> call. If the origin server returns a "{{Expires: 0}}" or "{{Expires:
> SOME_PAST_DATE}}" header, then TrafficServer appears to cache the first
> response briefly (around 1 second).
> I do not experience this same temporary cache when testing the other
> scenarios outlined in the documentation of what's not cached (for example,
> when the origin server responds with "{{Cache-Control: no-store}}" or
> "{{Set-Cookie}}").
> This isn't a huge deal for my use case personally, but the behavior I'm
> seeing does seem to run counter to the documentation, so I thought it was a
> bit odd.
> Here's some details demonstrating the cached response when requests are made
> in quick succession:
> {code}
> $ curl -v "http://localhost:8081/cacheable-expires-0/1"; && curl -v
> "http://localhost:8081/cacheable-expires-0/1";
> * About to connect() to localhost port 8081 (#0)
> * Trying ::1... Connection refused
> * Trying 127.0.0.1... connected
> * Connected to localhost (127.0.0.1) port 8081 (#0)
> > GET /cacheable-expires-0/1 HTTP/1.1
> > User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7
> > NSS/3.14.0.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
> > Host: localhost:8081
> > Accept: */*
> >
> < HTTP/1.1 200 OK
> < X-Powered-By: Express
> < Expires: 0
> < Date: Mon, 28 Jul 2014 01:49:45 GMT
> < Age: 0
> < Transfer-Encoding: chunked
> < Connection: keep-alive
> < Server: ATS/5.0.1
> <
> * Connection #0 to host localhost left intact
> * Closing connection #0
> 36780-926573328-0.49593452527187765
> * About to connect() to localhost port 8081 (#0)
> * Trying ::1... Connection refused
> * Trying 127.0.0.1... connected
> * Connected to localhost (127.0.0.1) port 8081 (#0)
> > GET /cacheable-expires-0/1 HTTP/1.1
> > User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7
> > NSS/3.14.0.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
> > Host: localhost:8081
> > Accept: */*
> >
> < HTTP/1.1 200 OK
> < X-Powered-By: Express
> < Expires: 0
> < Date: Mon, 28 Jul 2014 01:49:45 GMT
> < Age: 0
> < Content-Length: 35
> < Connection: keep-alive
> < Server: ATS/5.0.1
> <
> * Connection #0 to host localhost left intact
> * Closing connection #0
> 36780-926573328-0.49593452527187765
> {code}
> In this case, the origin server only gets called once (note the response
> bodies are identical, which should not be happening since the origin is
> returning a unique response body on each call). If I add in a sleep of around
> 0.8 seconds between calls, then TrafficServer's cached copy appears to go
> away:
> {code}
> $ curl -v "http://localhost:8081/cacheable-expires-0/1"; && sleep 0.8 && curl
> -v "http://localhost:8081/cacheable-expires-0/1";
> * About to connect() to localhost port 8081 (#0)
> * Trying ::1... Connection refused
> * Trying 127.0.0.1... connected
> * Connected to localhost (127.0.0.1) port 8081 (#0)
> > GET /cacheable-expires-0/1 HTTP/1.1
> > User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7
> > NSS/3.14.0.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
> > Host: localhost:8081
> > Accept: */*
> >
> < HTTP/1.1 200 OK
> < X-Powered-By: Express
> < Expires: 0
> < Date: Mon, 28 Jul 2014 01:51:16 GMT
> < Age: 0
> < Transfer-Encoding: chunked
> < Connection: keep-alive
> < Server: ATS/5.0.1
> <
> * Connection #0 to host localhost left intact
> * Closing connection #0
> 36871-310090571-0.9994140579365194
> * About to connect() to localhost port 8081 (#0)
> * Trying ::1... Connection refused
> * Trying 127.0.0.1... connected
> * Connected to localhost (127.0.0.1) port 8081 (#0)
> > GET /cacheable-expires-0/1 HTTP/1.1
> > User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7
> > NSS/3.14.0.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
> > Host: localhost:8081
> > Accept: */*
> >
> < HTTP/1.1 200 OK
> < X-Powered-By: Express
> < Expires: 0
> < Date: Mon, 28 Jul 2014 01:51:17 GMT
> < Age: 0
> < Transfer-Encoding: chunked
> < Connection: keep-alive
> < Server: ATS/5.0.1
> <
> * Connection #0 to host localhost left intact
> * Closing connection #0
> 36872-119374632-0.23531207791529596
> {code}
> With this sleep then the origin server is hit twice (note the response bodies
> differ indicating the origin server actually was hit twice).
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