Hi, Thanks for the info Alex. Patching code and building is a little beyond me tbh, especially as I would need this as a debian package to deploy to many machines. With that in mind I am trying the config workaround approach. Below is the config snippet I have added. I made the assumption that for the *refresh_pattern, max-stale=NN *config, the NN is in minutes as per the rest of that config directive. I am testing this right now
# this should allow stale objects up to 1 year if allowed by Cache-Control repsonse headers ... # ... setting both options just in case max_stale 525600 minutes refresh_pattern . 0 20% 4320 max-stale=525600 Thanks again for your help Robin On Thu, 8 Feb 2024 at 17:42, Alex Rousskov <rouss...@measurement-factory.com> wrote: > Hi Robin, > > AFAICT from the logs you have privately shared and your squid.conf > that you have posted earlier, your Squid overwrites > stale-if-error=31536000 in the response with "refresh_pattern > max-stale=0" default. That 0 value is wrong. The correct value should be > taken from max_stale directive that defaults to 1 week, not zero: > > refresh_pattern > ... > max-stale=NN provide a maximum staleness factor. Squid won't > serve objects more stale than this even if it failed to > validate the object. Default: use the max_stale global limit. > > This wrong default is a Squid bug AFAICT. I posted an _untested_ fix as > Squid PR 1664: https://github.com/squid-cache/squid/pull/1664 > > If possible, please test the corresponding patch: > > https://github.com/squid-cache/squid/commit/571973589b5a46d458311f8b60dcb83032fd5cec.patch > > AFAICT, you can also work around that bug by configuring an explicit > refresh_pattern rule with an explicit max-stale option (see > squid.conf.documented for examples). I have not tested that theory either. > > > HTH, > > Alex. > > > On 2024-02-07 13:45, Robin Carlisle wrote: > > Hi, > > > > I have just started my enhanced logging journey and have a small snippet > > below that might illuminate the issue ... > > > > /2024/02/07 17:06:39.212 kid1| 88,3| client_side_reply.cc(507) > > handleIMSReply: origin replied with error 502, forwarding to client due > > to fail_on_validation_err/ > > > > A few lines below in the log it looks like squid sent :- > > > > /2024/02/07 17:06:39.212 kid1| 11,2| Stream.cc(280) sendStartOfMessage: > > HTTP Client REPLY: > > --------- > > HTTP/1.1 502 Bad Gateway > > Server: squid/5.7 > > Mime-Version: 1.0 > > Date: Wed, 07 Feb 2024 17:06:39 GMT > > Content-Type: text/html;charset=utf-8 > > Content-Length: 3853 > > X-Squid-Error: ERR_READ_ERROR 0 > > Vary: Accept-Language > > Content-Language: en > > X-Cache: MISS from labs-maul-st-15 > > X-Cache-Lookup: HIT from labs-maul-st-15:3129 > > Via: 1.1 labs-maul-st-15 (squid/5.7) > > Connection: close/ > > > > > > The rest of the logs are quite large and contain URLs I cannot put > > here. The logs were generated with debug_options to ALL,3. > > > > Any ideas? Or should I generate more detailed logs and send them > > privately? > > > > Thanks again, > > > > Robin > > > > > > > > > > On Fri, 2 Feb 2024 at 11:20, Robin Carlisle > > <robin.carli...@framestore.com <mailto:robin.carli...@framestore.com>> > > wrote: > > > > Hi, thanks for your reply. > > > > I have been looking at : > > > https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control < > https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control> > > > > /The stale-if-error response directive indicates that the cache can > > reuse a stale response when an upstream server generates an error, > > or when the error is generated locally. Here, an error is considered > > any response with a status code of 500, 502, 503, or 504. > > > > Cache-Control: max-age=604800, stale-if-error=86400 > > In the example above, the response is fresh for 7 days (604800s). > > Afterwards, it becomes stale, but can be used for an extra 1 day > > (86400s) when an error is encountered. > > > > After the stale-if-error period passes, the client will receive any > > error generated/ > > > > Given what you have said and what the above docs say - I am still > > confused as it looks like (in my test cases) the cached response can > > be used for 3600 secs (this works), after which the cached response > > can still be used for an additional 31536000 seconds on an error > > (this doesnt work). > > > > I am going to dig into the error logging you suggested to see if I > > can make sense of that - and will send on if I can't. > > > > Thanks v much for your help again, > > > > Robin > > > > > > > > > > > > On Thu, 1 Feb 2024 at 18:27, Alex Rousskov > > <rouss...@measurement-factory.com > > <mailto:rouss...@measurement-factory.com>> wrote: > > > > On 2024-02-01 12:03, Robin Carlisle wrote: > > > Hi, I am having trouble with stale-if-error response. > > > > If I am interpreting Squid code correctly, in primary use cases: > > > > * without a Cache-Control:stale-if-error=X in the original > > response, > > Squid sends a stale object if revalidation results in a 5xx > error; > > > > * with a Cache-Control:stale-if-error=X and object age at most > > X, Squid > > sends a stale object if revalidation results in a 5xx error; > > > > * with a Cache-Control:stale-if-error=X and object age exceeding > X, > > Squid forwards the 5xx error response if revalidation results in > > a 5xx > > error; > > > > In other words, stale-if-error=X turns on a "fail on validation > > errors" > > behavior for stale objects older than X. It has no other effects. > > > > In your test case, the stale objects are much younger than > > stale-if-error value (e.g., Age~=3601 vs. > stale-if-error=31536000). > > Thus, stale-if-error should have no relevant effect. > > > > Something else is probably preventing your Squid from serving > > the stale > > response when facing a 5xx error. I do not know what that > > something is. > > > > I recommend sharing (privately if you need to protect sensitive > > info) a > > pointer to a compressed ALL,9 cache.log collected while > > reproducing the > > problem (using two transactions similar to the ones you have > shared > > below -- a successful stale hit and a problematic one): > > > https://wiki.squid-cache.org/SquidFaq/BugReporting#debugging-a-single-transaction > < > https://wiki.squid-cache.org/SquidFaq/BugReporting#debugging-a-single-transaction > > > > > > Alternatively, you can try to study cache.log yourself after > > setting > > debug_options to ALL,3. Searching for "refresh" and > > "handleIMSReply" may > > yield enough clues. > > > > > > HTH, > > > > Alex. > > > > > > > > > > > # /etc/squid/squid.conf : > > > > > > acl to_aws dstdomain .amazonaws.com <http://amazonaws.com> > > <http://amazonaws.com <http://amazonaws.com>> > > > > > > acl from_local src localhost > > > > > > http_access allow to_aws > > > > > > http_access allow from_local > > > > > > cache allow all > > > > > > cache_dir ufs /var/cache/squid 1024 16 256 > > > > > > http_port 3129 ssl-bump cert=/etc/squid/maul.pem > > > generate-host-certificates=on dynamic_cert_mem_cache_size=4MB > > > > > > sslcrtd_program /usr/lib/squid/security_file_certgen -s > > > /var/lib/squid/ssl_db -M 4MB > > > > > > acl step1 at_step SslBump1 > > > > > > ssl_bump bump step1 > > > > > > ssl_bump bump all > > > > > > sslproxy_cert_error deny all > > > > > > cache_store_log stdio:/var/log/squid/store.log > > > > > > logfile_rotate 0 > > > > > > shutdown_lifetime 3 seconds > > > > > > > > > # /usr/bin/proxy-test : > > > > > > #!/bin/bash > > > > > > curl --proxy http://localhost:3129 <http://localhost:3129> > > <http://localhost:3129 <http://localhost:3129>> \ > > > > > > --cacert /etc/squid/stuff.pem \ > > > > > > -v "https://stuff.amazonaws.com/api/v1/stuff/stuff.json > > <https://stuff.amazonaws.com/api/v1/stuff/stuff.json> > > > <https://stuff.amazonaws.com/api/v1/stuff/stuff.json > > <https://stuff.amazonaws.com/api/v1/stuff/stuff.json>>" \ > > > > > > -H "Authorization: token MYTOKEN" \ > > > > > > -H "Content-Type: application/json" \ > > > > > > --output "/tmp/stuff.json" > > > > > > > > > > > > Tests .......... > > > > > > > > > At this point in time the network cable is unattached. Squid > > returns > > > the cached object it got when the network was online earlier. > > The Age of > > > this object is just still under the max_age of 3600. > > Previously I > > > was using offline_mode but I found that it did not try to > > revalidate > > > from the origin after the object expired (defined via max-age > > response). > > > My understanding is that stale-if-error should work under > my > > > circumstances. > > > > > > > > > # /var/log/squid/access.log > > > > > > 1706799404.440 6 127.0.0.1 NONE_NONE/200 0 CONNECT > > > stuff.amazonaws.com:443 <http://stuff.amazonaws.com:443> > > <http://stuff.amazonaws.com:443 > > <http://stuff.amazonaws.com:443>> - HIER_NONE/- - > > > > > > 1706799404.440 0 127.0.0.1 TCP_MEM_HIT/200 20726 GET > > > https://stuff.amazonaws.com/stuff.json > > <https://stuff.amazonaws.com/stuff.json> > > > <https://stuff.amazonaws.com/stuff.json > > <https://stuff.amazonaws.com/stuff.json>> - HIER_NONE/- > > application/json > > > > > > > > > # extract from /usr/bin/proxy-test > > > > > > < HTTP/1.1 200 OK > > > > > > < Date: Thu, 01 Feb 2024 13:57:11 GMT > > > > > > < Content-Type: application/json > > > > > > < Content-Length: 20134 > > > > > > < x-amzn-RequestId: 3a2d3b26-df73-4b30-88cb-1a9268fa0df2 > > > > > > < Last-Modified: 2024-02-01T13:00:45.000Z > > > > > > < Access-Control-Allow-Origin: * > > > > > > < x-amz-apigw-id: SdZwpG7qiYcERUQ= > > > > > > < Cache-Control: public, max-age=3600, stale-if-error=31536000 > > > > > > < ETag: "cec102b43372840737ab773c2e77858b" > > > > > > < X-Amzn-Trace-Id: Root=1-65bba337-292be751134161b03555cdd6 > > > > > > < Age: 3573 > > > > > > < X-Cache: HIT from labs-maul-st-31 > > > > > > < X-Cache-Lookup: HIT from labs-maul-st-31:3129 > > > > > > < Via: 1.1 labs-maul-st-31 (squid/5.7) > > > > > > < Connection: keep-alive > > > > > > > > > > > > > > > Below .. the curl script executes again. The Age has gone > > over the > > > max-age so squid attempted to refresh from the origin. The > > machine is > > > still offline so the refresh failed. I expected that the > > > stale-if-error response would instruct squid to return the > > cached object > > > as a 200. > > > > > > > > > # /var/log/squid/access.log > > > > > > 1706799434.464 5 127.0.0.1 NONE_NONE/200 0 CONNECT > > > stuff.amazonaws.com:443 <http://stuff.amazonaws.com:443> > > <http://stuff.amazonaws.com:443 > > <http://stuff.amazonaws.com:443>> - HIER_NONE/- - > > > > > > 1706799434.464 0 127.0.0.1 TCP_REFRESH_FAIL_ERR/502 4235 > > GET > > > https://stuff.amazonaws.com/stuff.json > > <https://stuff.amazonaws.com/stuff.json> > > > <https://stuff.amazonaws.com/stuff.json > > <https://stuff.amazonaws.com/stuff.json>> - HIER_NONE/- > text/html > > > > > > > > > # extract from /usr/bin/proxy-test > > > > > > < HTTP/1.1 502 Bad Gateway > > > > > > < Server: squid/5.7 > > > > > > < Mime-Version: 1.0 > > > > > > < Date: Thu, 01 Feb 2024 14:57:14 GMT > > > > > > < Content-Type: text/html;charset=utf-8 > > > > > > < Content-Length: 3853 > > > > > > < X-Squid-Error: ERR_READ_ERROR 0 > > > > > > < Vary: Accept-Language > > > > > > < Content-Language: en > > > > > > < X-Cache: MISS from labs-maul-st-31 > > > > > > < X-Cache-Lookup: HIT from labs-maul-st-31:3129 > > > > > > < Via: 1.1 labs-maul-st-31 (squid/5.7) > > > > > > < Connection: close > > > > > > > > > > > > Hope someone can help me with this. All the best, > > > > > > > > > Robin Carlisle > > > > > > > > > > > > _______________________________________________ > > > squid-users mailing list > > > squid-users@lists.squid-cache.org > > <mailto:squid-users@lists.squid-cache.org> > > > https://lists.squid-cache.org/listinfo/squid-users > > <https://lists.squid-cache.org/listinfo/squid-users> > > > > _______________________________________________ > > squid-users mailing list > > squid-users@lists.squid-cache.org > > <mailto:squid-users@lists.squid-cache.org> > > https://lists.squid-cache.org/listinfo/squid-users > > <https://lists.squid-cache.org/listinfo/squid-users> > > > >
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