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Log configuration
Logs are very beneficial for statistics and troubleshooting. This article summarizes the nginx log-related configurations such as access_log, log_format, open_log_file_cache, log_not_found, log_subrequest, rewrite_log, error_log.
nginx has a very flexible log recording mode. Each level of configuration can have its own access log. The log format is defined by the log_format command.
ngx_http_log_module is used to define the request log format.
1. access_log directive
Syntax:
access_log path [format [buffer=size [flush=time]]]; access_log path format gzip[=level] [buffer=size] [flush=time]; access_log syslog:server=address[,parameter=value] [format]; access_log off;
Default value: access_log logs/access.log combined;
Configuration section: http, server, location, if in location, limit_except
gzip compression level.
buffer sets the size of the memory cache area.
flush keeps the longest time saved in the cache area.
Do not log: access_log off;
Log using the default combined format: access_log logs/access.log or access_log logs/access.log combined;
2. log_format instruction
Syntax: log_format name string …;
Default value: log_format combined "…"
Configuration section: http
name represents the format name, string represents the equivalent format. log_format has a default combined log format that does not need to be set, equivalent to the combined log format of Apache, as shown below:
log_format combined '$remote_addr - $remote_user [$time_local] "
" "$request" $status $body_bytes_sent "
" "$http_referer" "$http_user_agent" ""
If nginx is located after the load balancer, squid, and nginx reverse proxy, the web server cannot directly obtain the real IP address of the client. $remote_addr gets the IP address of the reverse proxy. The reverse proxy server can add X in the http header information of the forwarded request.-Forwarded-For information, used to record the client IP address and the server address requested by the client.
log_format porxy '$http_x_forwarded_for - $remote_user [$time_local] "
" "$request" $status $body_bytes_sent "
" "$http_referer" "$http_user_agent" ""
The comments on the variables that can be included in the log format are as follows:
$remote_addr, $http_x_forwarded_for (reverse) Records the client IP address $remote_user Records the client user name $request Records the URL and HTTP protocol of the request $status Records the request status $body_bytes_sent The number of bytes sent to the client, excluding the size of the response header; This variable is compatible with the "%B" parameter in the Apache module mod_log_config. $bytes_sent The total number of bytes sent to the client. $connection The serial number of the connection. $connection_requests The number of requests obtained through a connection. $msec The time of log writing. The unit is second, and the precision is millisecond. $pipe If the request is sent through HTTP pipelined (pipelined), the pipe value is "p", otherwise it is "." $http_referer records the page from which the access is linked $http_user_agent Records information about the client browser $request_length Length of the request (including the request line, request headers, and request body). $request_time Request processing time, in seconds, with millisecond precision; from the first byte read from the client to the log write after the last character is sent to the client. $time_iso8601 ISO8601Local time in the Standard Log Format. $time_local Local time in the Common Log Format.
[warning] The response headers sent to the client have the prefix 'sent_http_'. For example, $sent_http_content_range. [/warning]
Example as follows:
http {
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'"$status" $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for" '
'"$gzip_ratio" $request_time $bytes_sent $request_length';
log_format srcache_log '$remote_addr - $remote_user [$time_local] "$request" '
'"$status" $body_bytes_sent $request_time $bytes_sent $request_length '
'[$upstream_response_time] [$srcache_fetch_status] [$srcache_store_status] [$srcache_expire]';
open_log_file_cache max=1000 inactive=60s;
server {
server_name ~^(www\.)?(.+)$;
access_log logs/$2-access.log main;
error_log logs/$2-error.log;
location /srcache {
access_log logs/access-srcache.log srcache_log;
}
}
}
3. open_log_file_cache directive
Syntax:
open_log_file_cache max=N [inactive=time] [min_uses=N] [valid=time]; open_log_file_cache off;
Default: open_log_file_cache off;
Configuration sections: http, server, location
For each log entry, the file will be opened first, then the log will be written, and then closed. open_log_file_cache can be used to set the log file cache (default is off), in the format as follows:
Parameter comments as follows:
Example as follows:
open_log_file_cache max=1000 inactive=20s valid=1m min_uses=2;
4. log_not_found directive
Syntax: log_not_found on | off;
Default: log_not_found on;
Configuration sections: http, server, location
Whether to record non-existent errors in the error_log. Default is yes.
5. log_subrequest directive
Syntax: log_subrequest on | off;
Default: log_subrequest off;
Configuration sections: http, server, location
Whether to record the access logs of sub-requests in the access_log. Default is not recorded.
6. rewrite_log directive
Provided by ngx_http_rewrite_module module. Used to record rewrite logs. It is recommended to enable it for debugging rewrite rules. Nginx Rewrite Rule Guide
Syntax: rewrite_log on | off;
Default: rewrite_log off;
Configuration sections: http, server, location, if
When enabled, notice level rewrite logs will be recorded in the error log.
7. error_log directive
Syntax: error_log file | stderr | syslog:server=address[,parameter=value] [debug | info | notice | warn | error | crit | alert | emerg];
Default: error_log logs/error.log error;
Configuration section: main, http, server, location
Configure error logs.
--------------------------------------------------------------------------------
Log cutting
By default, nginx logs are all written into one file, which becomes very large and inconvenient to view and analyze. It is a good practice to cut logs by date, usually we do statistics on a daily basis. Let's talk about nginx log cutting below.
1. Define log rotation strategy
# vim nginx-log-rotate
/data/weblogs/*.log {
nocompress
daily
copytruncate
create
notifempty
rotate 7
olddir /data/weblogs/old_log
missingok
dateext
postrotate
/bin/kill -HUP `cat /var/run/nginx.pid 2> /dev/null` 2> /dev/null || true
endscript
}
[warning]/data/weblogs/*.log when using wildcards,/data/weblogs/All matching log files under the directory will be cut. If you want to cut a specific log file, specify the file. [/warning]
2. Set up a scheduled task
59 23 * * * root ( /usr/sbin/logrotate -f /PATH/TO/nginx-log-rotate)
such that every day23point59minute execution log cutting.
That's all for this article. I hope it will be helpful to everyone's learning and that everyone will support the Yell Tutorial more.
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