POST-Request to / receive a cached response (HDD-Cache)

[uvoelkel]

With the Apache-rewrite rules provided by the plugins Setup tab POST request to / receive a (hdd) cached answer.

I'm not entirely sure what exactly goes wrong but it seems that after the final WordPress rule RewriteRule . /index.php [L] is applied, all the rewrite rules are checked again (which apparently is how apache works. did not know that before). inside the subrequest the REQUEST_METHOD seems not to match the initial one which leads to a cached response being delivered for a POST request to /

1 [Wed Oct 07 13:35:09.120411 2020] [rewrite:trace3] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca020e0a0/initial] [perdir /var/www/html/] applying pattern '.' to uri '', referer: https://localhost/
2 [Wed Oct 07 13:35:09.120417 2020] [rewrite:trace1] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca020e0a0/initial] [perdir /var/www/html/] pass through /var/www/html/, referer: https://localhost/
3 [Wed Oct 07 13:35:09.120473 2020] [rewrite:trace3] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca02020a0/subreq] [perdir /var/www/html/] strip per-dir prefix: /var/www/html/index.php -> index.php, referer: https://localhost/
4 [Wed Oct 07 13:35:09.120490 2020] [rewrite:trace3] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca02020a0/subreq] [perdir /var/www/html/] applying pattern '.*' to uri 'index.php', referer: https://localhost/
...
5 [Wed Oct 07 13:35:09.120627 2020] [rewrite:trace4] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca02020a0/subreq] [perdir /var/www/html/] RewriteCond: input='GET' pattern='!=POST' => matched, referer: https://localhost/
6 [Wed Oct 07 13:35:09.120634 2020] [rewrite:trace4] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca02020a0/subreq] [perdir /var/www/html/] RewriteCond: input='' pattern='=""' => matched, referer: https://localhost/
7 [Wed Oct 07 13:35:09.120640 2020] [rewrite:trace4] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca02020a0/subreq] [perdir /var/www/html/] RewriteCond: input='/index.php' pattern='!^/(wp-admin|wp-content/cache)/.*' => matched, referer: https://localhost/
...
8 [Wed Oct 07 13:35:09.120683 2020] [rewrite:trace2] [pid 61:tid 140516971439872] mod_rewrite.c(483): [client 192.168.96.1:55700] 192.168.96.1 - - [localhost/sid#7fccb5d18420][rid#7fcca02020a0/subreq] [perdir /var/www/html/] rewrite 'index.php' -> '/wp-content/cache/cachify/https-localhost/index.html.gz', referer: https://localhost/

line 1: is the final WordPress rule RewriteRule . /index.php [L]
which results in a subrequest (lines 2 and 3)
line 4 is the first cachify rule RewriteRule .* - [E=CACHIFY_HOST:https-%{HTTP_HOST}] this time applied to the subrequest to index.php
line 5 shows that for the subrequest the method is GET
6 & 7 are the cachify conditions
RewriteCond %{REQUEST_URI} !^/(wp-admin|wp-content/cache)/.*
RewriteCond %{HTTP_COOKIE} !(wp-postpass|wordpress_logged_in|comment_author)_
and in line 8 it gets rewritten to the cached path

I "fixed" it by prepending RewriteCond %{REQUEST_URI} /$ to the Main Rules block which makes the whole "set subdirectory" block useless. I'm not sure under which circumstances the condition RewriteCond %{REQUEST_URI} ^$ is true so im not sure if my "fix" breaks other setups.

[chesio]

Hi @uvoelkel,

I guess I stumbled upon the same problem with BC Cache (fork of Cachify). My solution was to add NS flag to the RewriteRule, see: chesio/bc-cache#6 It should work with Cachify as well.