I have a question about the HTTP status code when Apache is acting as a caching reverse proxy and receives a 500 error from the backend server. I *believe* I have it properly configured to serve the stale content that is in the cache.
CacheStaleOnError doc states
When the CacheStaleOnError directive is switched on, and when stale data is available in the cache, the cache will respond to 5xx responses from the backend by returning the stale data instead of the 5xx response.
Here are my logs (edited). The requests are from a load balancer monitoring the server.
www.host.net:80 cache hit x.x.x.8 "-" - - [13/Aug/2015:06:21:12 +0000] "GET / HTTP/1.1" 200 80951 "-" "-"
www.host.net:80 cache hit x.x.x.8 "-" - - [13/Aug/2015:06:21:14 +0000] "GET / HTTP/1.1" 200 80951 "-" "-"
www.host.net:80 cache hit x.x.x.8 "-" - - [13/Aug/2015:06:21:14 +0000] "GET / HTTP/1.1" 500 80951 "-" "-"
www.host.net:80 cache hit x.x.x.8 "-" - - [13/Aug/2015:06:21:17 +0000] "GET / HTTP/1.1" 200 80951 "-" "-"
Note the third request has a 500 response but the same content length as the other requests. So I think what is happening is that the stale content is being server with a 500 error code. This would probably be fine if a browser sees the content since it will display the content as an error page and be fairly invisible for the end user. But our load balancer is specifically looking for at the response code and marks the serve as down.
Does anyone know if this is expected beahviour?
