[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 18:49:35 UTC 2021

I've probably replied to quickly thinking there is a way to do it. So
looking at the code and reading carefully your response, you're saying
there is no way you can do it with squid.

Mirek

On Wed, Mar 24, 2021 at 6:28 PM Miroslaw Malinowski <
mr.miroslaw.malinowski at gmail.com> wrote:

> 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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