[squid-users] squid won't return cached even with refresh_pattern extra options override-lastmod override-expire ignore-reload ignore-no-store ignore-private store-stale

Wed Mar 24 18:28:51 UTC 2021

Hi,

You've right yes it's revalidating as API server I'm requesting data is
setting Cache-Control: no-cache. My question is how I can force squid to
cache and not validate as I know it's safe to do so. As I've explained
earlier we are making the same request and receiving the same response from
100+ server so as to reduce number of requests to the external server we
would like squid to cache the response and issue a cached version.

2021/03/24 18:00:54.867 kid1| 22,3| refresh.cc(351) refreshCheck: YES: Must
revalidate stale object (origin set no-cache or private)

Mirek

On Wed, Mar 24, 2021 at 6:15 PM Alex Rousskov <
rousskov at measurement-factory.com> wrote:

> On 3/24/21 12:48 PM, Miroslaw Malinowski wrote:
>
> > Probably, me missing on something silly or it can't be done but I don't
> > know why but squid won't return the cached version even when I turn all
> > override options ON in refresh_pattern.
>
> AFAICT, no configuration options that can disable revalidation of
> Cache-Control:no-cache responses. refresh_pattern does not have an
> (equivalent of) "ignore-no-cache-in-responses" option.
>
> IIRC, older Squids were violating an HTTP MUST by forgetting to
> revalidate Cache-Control:no-cache responses, but that was fixed in [1].
> Your Squid version has that fix.
>
> [1]
>
> https://github.com/squid-cache/squid/commit/fa83b766a208b27abed8da4c9073cf8784cf10fa
>
>
> > With debug, I can see the rule is matched and the cache is fresh but
> > still in access.log is TCP_REFRESH_MODIFIED
>
> > 2021-03-24T15:04:34   squid   .710 kid1| 11,3| http.cc(982)
> > haveParsedReplyHeaders: decided: cache positively and share because
>
> FYI: You are looking at cache.log lines logged _after_ Squid has already
> decided to refresh the cached version. If you want to analyze why Squid
> decided to refresh the cached version, you should look _before_ Squid
> logged the request to the server (and before any FwdState.cc lines). I
> have not checked the details, but I bet that your Squid revalidates
> because of Cache-Control:no-cache in the response. Look for "YES: Must
> revalidate stale object".
>
>
> HTH,
>
> Alex.
>
> > squid conf:
> > refresh_pattern -i <URL> 4320 80% 129600 override-lastmod
> > override-expire ignore-reload ignore-no-store ignore-private store-stale
> >
> > curl headers:
> > curl --insecure --verbose --request GET --url 'URL' >/dev/null
> > * TCP_NODELAY set
> > * ALPN, offering h2
> > * ALPN, offering http/1.1
> > * successfully set certificate verify locations:
> > *   CAfile: /etc/ssl/certs/ca-certificates.crt
> >  CApath: /etc/ssl/certs
> > } [5 bytes data]
> > * TLSv1.3 (OUT), TLS handshake, Client hello (1):
> > } [512 bytes data]
> > * TLSv1.3 (IN), TLS handshake, Server hello (2):
> > { [122 bytes data]
> > * TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
> > { [6 bytes data]
> > * TLSv1.3 (IN), TLS handshake, Certificate (11):
> > { [1956 bytes data]
> > * TLSv1.3 (IN), TLS handshake, CERT verify (15):
> > { [78 bytes data]
> > * TLSv1.3 (IN), TLS handshake, Finished (20):
> > { [52 bytes data]
> > * TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
> > } [1 bytes data]
> > * TLSv1.3 (OUT), TLS handshake, Finished (20):
> > } [52 bytes data]
> > * SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
> >
> >> GET URL HTTP/1.1
> >> Host: URL
> >> User-Agent: curl/7.68.0
> >> Accept: */*
> >>
> > { [5 bytes data]
> > * TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
> > { [217 bytes data]
> > * TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
> > { [217 bytes data]
> > * old SSL session ID is stale, removing
> > { [5 bytes data]
> > * Mark bundle as not supporting multiuse
> > < HTTP/1.1 200 OK
> > < Cache-Control: no-cache
> > < Content-Type: application/json
> > < X-Cloud-Trace-Context: d3c27833b8b4312ce31a2dbae7e12fd0
> > < Date: Wed, 24 Mar 2021 15:04:34 GMT
> > < Server: Google Frontend
> > < Content-Length: 7950
> > < X-Cache: MISS from server
> > < X-Cache-Lookup: HIT from server
> > < Via: 1.1 server (squid/4.14)
> > < Connection: keep-alive
> >
> > access log:
> > 243 172.16.230.249 TCP_REFRESH_MODIFIED/200 8328 GET URL -
> > ORIGINAL_DST/IP application/json
> >
> > cache log:
> > 2021-03-24T15:04:34   squid   .710 kid1| 11,3| http.cc(982)
> > haveParsedReplyHeaders: decided: cache positively and share because
> > refresh check returned cacheable; HTTP status 200
> e:=p2V/0x34868914670*3
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(470)
> refreshCheck:
> > returning FRESH_MIN_RULE
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(455)
> refreshCheck:
> > Object isn't stale..
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(327)
> refreshCheck:
> > Staleness = -1
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(199)
> > refreshStaleness: FRESH: age (60 sec) is less than configured minimum
> > (259200 sec)
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(166)
> > refreshStaleness: No explicit expiry given, using heuristics to
> > determine freshness
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(307)
> refreshCheck:
> > entry->timestamp: Wed, 24 Mar 2021 15:04:34 GMT
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(305)
> refreshCheck:
> > check_time: Wed, 24 Mar 2021 15:05:34 GMT
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(303)
> refreshCheck:
> > age: 60
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(301)
> refreshCheck:
> > Matched 'URL 259200 80%% 7776000'
> > 2021-03-24T15:04:34   squid   .710 kid1| 22,3| refresh.cc(279)
> refreshCheck:
> > checking freshness of URI: https://URL <https://URL>
> >
> >
> > _______________________________________________
> > squid-users mailing list
> > squid-users at lists.squid-cache.org
> > http://lists.squid-cache.org/listinfo/squid-users
> >
>
>
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