Logs external to us show that requests to our Apache server are occasionally responded to with 502 status. However, there are no corresponding entries in the site or apache-wide access or error logs. I have verified that these files have the correct permissions and ownership and that other content is being written to them.
Our setup is that requests come into Apache and are reverse proxied to docker containers running nginx/Rails. None of the logs in this path show that there was a request.
The issue is intermittent and there doesn't seem to be a pattern in it other than that.
Server version: Apache/2.4.29 (Ubuntu)
Server built: 2021-09-28T22:27:27
Server's Module Magic Number: 20120211:68
Server loaded: APR 1.6.3, APR-UTIL 1.6.1
Compiled using: APR 1.6.3, APR-UTIL 1.6.1
Architecture: 64-bit
Server MPM: event
threaded: yes (fixed thread count)
forked: yes (variable process count)
Server compiled with....
-D APR_HAS_SENDFILE
-D APR_HAS_MMAP
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
-D APR_USE_SYSVSEM_SERIALIZE
-D APR_USE_PTHREAD_SERIALIZE
-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
-D APR_HAS_OTHER_CHILD
-D AP_HAVE_RELIABLE_PIPED_LOGS
-D DYNAMIC_MODULE_LIMIT=256
-D HTTPD_ROOT="/etc/apache2"
-D SUEXEC_BIN="/usr/lib/apache2/suexec"
-D DEFAULT_PIDLOG="/var/run/apache2.pid"
-D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
-D DEFAULT_ERRORLOG="logs/error_log"
-D AP_TYPES_CONFIG_FILE="mime.types"
-D SERVER_CONFIG_FILE="apache2.conf"
How can I debug this further?
