# Is it possible to capture response headers in access log when using nginx as a reverse proxy? **URL:** \ **Category:** NGINX\ **Created:** [November 25, 2010, 1:19am UTC](https://www.ruby-forum.com/t/is-it-possible-to-capture-response-headers-in-access-log-when-using-nginx-as-a-reverse-proxy/199613 "2010-11-25T01:19:28Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Dobai-Pataky\_BSSSSl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/77aa72/32.png) [@Dobai-Pataky\_BSSSSl](https://www.ruby-forum.com/u/Dobai-Pataky_BSSSSl)\ **Post date:** [November 25, 2010, 1:19am UTC](https://www.ruby-forum.com/t/is-it-possible-to-capture-response-headers-in-access-log-when-using-nginx-as-a-reverse-proxy/199613/1 "2010-11-25T01:19:28Z")
Below is a question I originally posted on Stack Overflow. Feel free to respond there if you use that site: > Hi, We are using nginx as a reverse proxy to control and log access to a Clojure (Java) web service application. We are able to generate an access\_log and capture incoming headers using nginx just fine. Our Clojure app logs activity via log4j. Trouble is, is that we can’t match an entry in the access\_log to an entry generated by the app. The app responds to access by sending response headers as well as a body. We can freely change these response headers. My initial thought was to generate a UUID that corresponds to each and every web service request and send that back to the user within the reply header X-Uuid. My thought was that I could capture this response by creating a custom log\_format: log\_format lt-custom '$remote\_addr - $remote\_user [$time\_local] ’ '“$request” $status $body\_bytes\_sent ’ ‘“$http\_referer” “$http\_user\_agent” $request\_time $http\_x\_uuid’; It’s looking like nginx can capture headers in incoming requests but not outgoing replies (I verified this by replacing $http\_x\_uuid with $http\_content\_type). So! Is there a way I can tie my access\_log enties and my log4j entries by capturing outgoing reply headers using nginx? Is there a better way? I’d rather not have to rely on users generating their own UUIDs. Thanks so much! Posted at Nginx Forum: > **[Is it possible to capture response headers in access log when using nginx as...](https://forum.nginx.org/read.php?2,153136,153136#msg-153136)** > > Below is a question I originally posted on Stack Overflow. Feel free to respond there if you use that site: http://stackoverflow.com/questions/4272686/nginx-is-it-possible-to-capture-response-headers-in-access-log-when-using-nginx Hi, We are using... ---
**Author:** ![johndavideriksen](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e0b2c6/32.png) [@johndavideriksen](https://www.ruby-forum.com/u/johndavideriksen)\ **Post date:** [November 25, 2010, 12:06pm UTC](https://www.ruby-forum.com/t/is-it-possible-to-capture-response-headers-in-access-log-when-using-nginx-as-a-reverse-proxy/199613/2 "2010-11-25T12:06:51Z")
Hello! On Wed, Nov 24, 2010 at 07:17:29PM -0500, johndavideriksen wrote: > nginx just fine. Our Clojure app logs activity via log4j. Trouble is, is > log\_format lt-custom '$remote\_addr - $remote\_user [$time\_local] ’ > I’d rather not have to rely on users generating their own UUIDs. > Headers returned by upstream server are available via > $upstream\_http\_\* variables, see here: > **[GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki...](https://github.com/nginxinc/nginx-wiki)** > > ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com Headers sent to client (these may be different from ones returned by upstream) are available via $sent\_http\_\* variables, see here: > **[GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki...](https://github.com/nginxinc/nginx-wiki)** > > ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com Maxim D.