Detailed explanation of nginx log printing request header information example

question:

When I found out that when nginx forwarding, I seemed to lose the fields customized in the request header~~, so I wanted to try to print out the request header and find out the specific reason.

1. Print the nigx request header

Just simply modify the configuration below

http {
    include       ;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_user_id" "$http_accept_language" ';

    access_log  logs/  main;

    sendfile        on;
    #tcp_nopush     on;
    underscores_in_headers on;

    #keepalive_timeout  0;
    keepalive_timeout  65;
    server_names_hash_bucket_size 512;
    client_max_body_size 500m;
    client_header_buffer_size 32k;
    large_client_header_buffers 4 32k;
}

The changed location is

log_format , the custom parameter in the print request header is user_id, so you need to add "$http_user_id" to the configuration. Yes, with the $http_ prefix

access_log logs/ main; make it print in the log and view the log

2. But mine doesn't work

After continuous attempts, I discovered a problem.My custom key is user_id, but by default, nginx does not support underscore fields!

That is to say, if it is user-id, then there is no problem

The field I need now is user_id

Add the following configuration in:

underscores_in_headers on;

It's still an http module, there is already

Summarize

• Print variables in the request header, you need to prefix $http_
• When you want nginx forward or print variables with underscores, you need to enable underscores_in_headers on;

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