This might be better for the developers list, but I am having an issue where apache 2.4.6 acting as a reverse proxy is caching 503 error messages which I don't understand at all. The proxy is a simple proxypass directive, the backend server is apache proxying to an oracle ucm instance. When I hit the proxy while both apaches are running but not the ucm instance, I get a 503 response (expected). Apache is appropriately serving stale content, but when that content expires (or I remove the cached content) then apache caches the 503 response and will serve it even after the server is back up.
Here is the relevant part of the log
[Thu Oct 17 21:29:15.038716 2013] [proxy:debug] [pid 27382] proxy_util.c(2194): [client 192.168.252.52:39745] AH00947: connected / to MYBACKENDSERVER
[Thu Oct 17 21:29:47.062046 2013] [proxy_http:trace3] [pid 27382] mod_proxy_http.c(1403): [client 192.168.252.52:39745] Status from backend: 503
[Thu Oct 17 21:29:47.062103 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1086): [client 192.168.252.52:39745] Headers received from backend:
[Thu Oct 17 21:29:47.062137 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Date: Thu, 17 Oct 2013 21:29:18 GMT
[Thu Oct 17 21:29:47.062245 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Server: Apache
[Thu Oct 17 21:29:47.062266 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Content-Type: text/html
[Thu Oct 17 21:29:47.062283 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Cache-Control: public
[Thu Oct 17 21:29:47.062299 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Expires: Thu, 17 Oct 2013 21:44:18 GMT
[Thu Oct 17 21:29:47.062319 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Vary: Accept-Encoding
[Thu Oct 17 21:29:47.062336 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Content-Length: 237
[Thu Oct 17 21:29:47.062352 2013] [proxy_http:trace4] [pid 27382] mod_proxy_http.c(1088): [client 192.168.252.52:39745] Connection: close
[Thu Oct 17 21:29:47.062389 2013] [proxy_http:trace3] [pid 27382] mod_proxy_http.c(1654): [client 192.168.252.52:39745] start body send
[Thu Oct 17 21:29:47.063336 2013] [deflate:debug] [pid 27382] mod_deflate.c(764): [client 192.168.252.52:39745] AH01384: Zlib: Compressed 237 to 177 : URL /
[Thu Oct 17 21:29:47.063450 2013] [cache:debug] [pid 27382] mod_cache.c(1326): [client 192.168.252.52:39745] AH00769: cache: Caching url: /
[Thu Oct 17 21:29:47.063515 2013] [cache:debug] [pid 27382] mod_cache.c(1332): [client 192.168.252.52:39745] AH00770: cache: Removing CACHE_REMOVE_URL filter.
[Thu Oct 17 21:29:47.063657 2013] [http:trace3] [pid 27382] http_filters.c(963): [client 192.168.252.52:39745] Response sent with status 503, headers:
[Thu Oct 17 21:29:47.063683 2013] [http:trace5] [pid 27382] http_filters.c(970): [client 192.168.252.52:39745] Date: Thu, 17 Oct 2013 21:29:18 GMT
[Thu Oct 17 21:29:47.063694 2013] [http:trace5] [pid 27382] http_filters.c(973): [client 192.168.252.52:39745] Server:
Apache
[Thu Oct 17 21:29:47.063709 2013] [http:trace4] [pid 27382] http_filters.c(806): [client 192.168.252.52:39745] Content-Type: text/html
[Thu Oct 17 21:29:47.063721 2013] [http:trace4] [pid 27382] http_filters.c(806): [client 192.168.252.52:39745] Cache-Control: public,max-age=900
[Thu Oct 17 21:29:47.063733 2013] [http:trace4] [pid 27382] http_filters.c(806): [client 192.168.252.52:39745] Vary: Accept-Encoding
[Thu Oct 17 21:29:47.063744 2013] [http:trace4] [pid 27382] http_filters.c(806): [client 192.168.252.52:39745] Content-Encoding: gzip
[Thu Oct 17 21:29:47.063755 2013] [http:trace4] [pid 27382] http_filters.c(806): [client 192.168.252.52:39745] Connection:
close
[Thu Oct 17 21:29:47.063766 2013] [http:trace4] [pid 27382] http_filters.c(806): [client 192.168.252.52:39745] Transfer-Encoding: chunked
[Thu Oct 17 21:29:47.064575 2013] [cache_disk:debug] [pid 27382] mod_cache_disk.c(1349): [client 192.168.252.52:39745] AH00737: commit_entity: Headers and body for URL http://www.nature.org:80/? cached.
[Thu Oct 17 21:29:47.064644 2013] [proxy_http:trace2] [pid 27382] mod_proxy_http.c(1793): [client 192.168.252.52:39745] end body send
Anyone have a clue?
