https://hub.docker.com/r/lucascimon/nginx-logging-proxy/

This simple demo aims to demonstrate how to setup a simple nginx Docker service (with docker-compose or docker stack) to log requests made to another service.

It originates from the following needs & constraints:

• we needed to debug some HTTP calls (which we suspected included CRLF control characters) made to a Docker-deployed endpoint
• we couldn't use external public services like RequestBin to inspect those requests because we were in a private isolated company infrastructure
• the awesome httbin project does not currently log requests it receives, and gunicorn cannot dump the request body in its access logs

Hence we used a simple nginx Docker recipe to intercept and log requests.

Demo

Let's start from the following basic docker-compose.yaml:

version: '3'
services:
  httpbin:
    build: ./httpbin
    ports:
      - "8000:8000"

Here httpbin plays the role of the final endpoint (with the added advantage of logging the request Content-Type), but really it could be any docker-compose / docker stack service for which you want to intercept requests.

Now, with only 5 lines added to this YAML file, you can get the query string and body in your Docker logs:

• in one terminal:

docker-compose up

• in another one:

curl http://localhost:8000/post?foo=bar -d "$(echo -e 'TEST\r\n')"

Result:

httpbin_1              | 172.20.0.3 [20/Mar/2018:12:34:46 +0000] POST /post?foo=bar HTTP/1.1 200 Content-Type: application/x-www-form-urlencoded
nginx-logging-proxy_1  | 172.20.0.1 [20/Mar/2018:12:34:46 +0000] POST /post?foo=bar HTTP/1.1 200 req_time=0.003 body=TEST\x0D