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view xml/en/docs/http/ngx_http_log_module.xml @ 963:2116a99dc304
"Nginx HTTP Server - Second Edition" book added.
author | Valentin Bartenev <vbart@nginx.com> |
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date | Mon, 12 Aug 2013 13:20:13 +0400 |
parents | 488a3f738db0 |
children | 95c3c3bbf1ce |
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<?xml version="1.0"?> <!-- Copyright (C) Igor Sysoev Copyright (C) Nginx, Inc. --> <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> <module name="Module ngx_http_log_module" link="/en/docs/http/ngx_http_log_module.html" lang="en" rev="10"> <section id="summary"> <para> The <literal>ngx_http_log_module</literal> module writes request logs in the specified format. </para> <para> Requests are logged in a context of a location where processing ends. This may be different from the original location, if an <link doc="ngx_http_core_module.xml" id="internal">internal redirect</link> happens during request processing. </para> </section> <section id="example" name="Example Configuration"> <para> <example> log_format compression '$remote_addr - $remote_user [$time_local] ' '"$request" $status $bytes_sent ' '"$http_referer" "$http_user_agent" "$gzip_ratio"'; access_log /spool/logs/nginx-access.log compression buffer=32k; </example> </para> </section> <section id="directives" name="Directives"> <directive name="access_log"> <syntax> <value>path</value> [<value>format</value> [<literal>buffer</literal>=<value>size</value> [<literal>flush</literal>=<value>time</value>]]]</syntax> <syntax> <value>path</value> <value>format</value> <literal>gzip[=<value>level</value>]</literal> [<literal>buffer</literal>=<value>size</value>] [<literal>flush</literal>=<value>time</value>]</syntax> <syntax> <literal>syslog:</literal><literal>server</literal>=<value>address</value>[,<value>parameter</value>=<value>value</value>] [<value>format</value>]</syntax> <syntax><literal>off</literal></syntax> <default>logs/access.log combined</default> <context>http</context> <context>server</context> <context>location</context> <context>if in location</context> <context>limit_except</context> <para> Sets the path, format, and configuration of the buffered log writes. Several logs can be specified on the same level. Logging to syslog can be configured by specifying the “<literal>syslog:</literal>” prefix in the first parameter. The special value <literal>off</literal> cancels all <literal>access_log</literal> directives on the current level. If format is not specified then the predefined format “<literal>combined</literal>” is used. </para> <para> If either the <literal>buffer</literal> or <literal>gzip</literal> (1.3.10, 1.2.7) parameter is used, writes to log will be buffered. <note> The buffer size must not exceed the size of the atomic write to a disk file. For FreeBSD this size is unlimited. </note> </para> <para> When buffering is enabled, the data will be written to the file: <list type="bullet"> <listitem> if the next log line does not fit into the buffer; </listitem> <listitem> if the buffered data is older than specified by the <literal>flush</literal> parameter (1.3.10, 1.2.7); </listitem> <listitem> when a worker process is <link doc="../control.xml">re-opening</link> log files or is shutting down. </listitem> </list> </para> <para> If the <literal>gzip</literal> parameter is used, then the buffered data will be compressed before writing to the file. The compression level can be set between 1 (fastest, less compression) and 9 (slowest, best compression). By default the buffer size is equal to 64K bytes, and the compression level is set to 1. Since the data is compressed in atomic blocks, the log file can be decompressed or read by “<literal>zcat</literal>” at any time. </para> <para> Example: <example> access_log /path/to/log.gz combined gzip flush=5m; </example> </para> <para> <note> For gzip compression to work, nginx must be built with the zlib library. </note> </para> <para> The file path can contain variables (0.7.6+), but such logs have some constraints: <list type="bullet"> <listitem> the <link doc="../ngx_core_module.xml" id="user"/> whose credentials are used by worker processes should have permissions to create files in a directory with such logs; </listitem> <listitem> buffered writes do not work; </listitem> <listitem> a file is opened and closed for each log write. However, since the descriptors of frequently used files can be stored in a <link id="open_log_file_cache">cache</link>, writes during the time specified by the <literal>valid</literal> parameter of the <link id="open_log_file_cache"/> directive can continue to be made to the old file. </listitem> <listitem> during each log write the existence of the request’s <link doc="ngx_http_core_module.xml" id="root">root directory</link> is checked, and if it does not exist the log is not created. It is thus a good idea to specify both <link doc="ngx_http_core_module.xml" id="root"/> and <literal>access_log</literal> on the same level: <example> server { root /spool/vhost/data/$host; access_log /spool/vhost/logs/$host; ... </example> </listitem> </list> </para> <para> The following parameters configure logging to syslog: <list type="tag"> <tag-name><literal>server=</literal><value>address</value></tag-name> <tag-desc> Defines the address of a syslog server. The address can be specified as a domain name, IP address, or a UNIX-domain socket path (specified after the “<literal>unix:</literal>” prefix). With a domain name or IP address, the port can be specified. If port is not specified, the port 514 is used. If a domain name resolves to several IP addresses, the first resolved address is used. </tag-desc> <tag-name><literal>facility=</literal><value>string</value></tag-name> <tag-desc> Sets facility of syslog messages, as defined in <link url="http://tools.ietf.org/html/rfc3164#section-4.1.1">RFC 3164</link>. Facility can be one of “<literal>kern</literal>”, “<literal>user</literal>”, “<literal>mail</literal>”, “<literal>daemon</literal>”, “<literal>auth</literal>”, “<literal>intern</literal>”, “<literal>lpr</literal>”, “<literal>news</literal>”, “<literal>uucp</literal>”, “<literal>clock</literal>”, “<literal>authpriv</literal>”, “<literal>ftp</literal>”, “<literal>ntp</literal>”, “<literal>audit</literal>”, “<literal>alert</literal>”, “<literal>cron</literal>”, “<literal>local0</literal>”..“<literal>local7</literal>”. Default is “<literal>local7</literal>”. </tag-desc> <tag-name><literal>severity=</literal><value>string</value></tag-name> <tag-desc> Sets severity of syslog messages, as defined in <link url="http://tools.ietf.org/html/rfc3164#section-4.1.1">RFC 3164</link>. Possible values are the same as for the second parameter (level) of the <link doc="../ngx_core_module.xml" id="error_log"/> directive. Default is “<literal>info</literal>”. </tag-desc> <tag-name><literal>tag=</literal><value>string</value></tag-name> <tag-desc> Sets the tag of syslog messages. Default is “<literal>nginx</literal>”. </tag-desc> <!-- <tag-name><literal>bare=</literal><literal>on</literal> | <literal>off</literal></tag-name> <tag-desc> If enabled, messages are sent without syslog headers. Default is <literal>off</literal>. </tag-desc> --> </list> Example syslog configuration: <example> access_log syslog:server=192.168.1.1; access_log syslog:server=unix:/var/log/nginx.sock; access_log syslog:server=[2001:db8::1]:12345,facility=local7,tag=nginx,severity=info combined; </example> </para> <para> <note> Logging to syslog is available as part of our <commercial_version/> only. </note> </para> </directive> <directive name="log_format"> <syntax> <value>name</value> <value>string</value> ...</syntax> <default>combined "..."</default> <context>http</context> <para> Specifies format of a log. </para> <para> The log format can contain common variables, and variables that exist only at the time of a log write: <list type="tag"> <tag-name><var>$bytes_sent</var></tag-name> <tag-desc> the number of bytes sent to a client </tag-desc> <tag-name><var>$connection</var></tag-name> <tag-desc> connection serial number </tag-desc> <tag-name><var>$connection_requests</var></tag-name> <tag-desc> the current number of requests made through a connection (1.1.18) </tag-desc> <tag-name><var>$msec</var></tag-name> <tag-desc> time in seconds with a milliseconds resolution at the time of log write </tag-desc> <tag-name><var>$pipe</var></tag-name> <tag-desc> “<literal>p</literal>” if request was pipelined, “<literal>.</literal>” otherwise </tag-desc> <tag-name><var>$request_length</var></tag-name> <tag-desc> request length (including request line, header, and request body) </tag-desc> <tag-name><var>$request_time</var></tag-name> <tag-desc> request processing time in seconds with a milliseconds resolution; time elapsed between the first bytes were read from the client and the log write after the last bytes were sent to the client </tag-desc> <tag-name><var>$status</var></tag-name> <tag-desc> response status </tag-desc> <tag-name><var>$time_iso8601</var></tag-name> <tag-desc> local time in the ISO 8601 standard format </tag-desc> <tag-name><var>$time_local</var></tag-name> <tag-desc> local time in the Common Log Format </tag-desc> </list> <note> In modern versions of nginx variables <link doc="ngx_http_core_module.xml" id="var_status">$status</link> (1.3.2, 1.2.2), <link doc="ngx_http_core_module.xml" id="var_bytes_sent">$bytes_sent</link> (1.3.8, 1.2.5), <link doc="ngx_http_core_module.xml" id="var_connection">$connection</link> (1.3.8, 1.2.5), <link doc="ngx_http_core_module.xml" id="var_connection_requests">$connection_requests</link> (1.3.8, 1.2.5), <link doc="ngx_http_core_module.xml" id="var_msec">$msec</link> (1.3.9, 1.2.6), <link doc="ngx_http_core_module.xml" id="var_request_time">$request_time</link> (1.3.9, 1.2.6), <link doc="ngx_http_core_module.xml" id="var_pipe">$pipe</link> (1.3.12, 1.2.7), <link doc="ngx_http_core_module.xml" id="var_request_length">$request_length</link> (1.3.12, 1.2.7), <link doc="ngx_http_core_module.xml" id="var_time_iso8601">$time_iso8601</link> (1.3.12, 1.2.7), and <link doc="ngx_http_core_module.xml" id="var_time_local">$time_local</link> (1.3.12, 1.2.7) are also available as common variables. </note> </para> <para> Header lines sent to a client have the prefix “<literal>sent_http_</literal>”, for example, <var>$sent_http_content_range</var>. </para> <para> The configuration always includes the predefined format “<literal>combined</literal>”: <example> log_format combined '$remote_addr - $remote_user [$time_local] ' '"$request" $status $body_bytes_sent ' '"$http_referer" "$http_user_agent"'; </example> </para> </directive> <directive name="open_log_file_cache"> <syntax> <literal>max</literal>=<value>N</value> [<literal>inactive</literal>=<value>time</value>] [<literal>min_uses</literal>=<value>N</value>] [<literal>valid</literal>=<value>time</value>]</syntax> <syntax><literal>off</literal></syntax> <default>off</default> <context>http</context> <context>server</context> <context>location</context> <para> Defines a cache that stores file descriptors of frequently used logs whose names contain variables. The directive has the following parameters: <list type="tag"> <tag-name><literal>max</literal></tag-name> <tag-desc> sets a maximum number of descriptors in a cache; if cache becomes full the least recently used (LRU) descriptors are closed </tag-desc> <tag-name><literal>inactive</literal></tag-name> <tag-desc> sets a time after which the cached descriptor is closed if there were no access during this time; by default, 10 seconds </tag-desc> <tag-name><literal>min_uses</literal></tag-name> <tag-desc> sets a minimum number of file uses during the time defined by the <literal>inactive</literal> parameter after which the descriptor will stay open in a cache; by default, 1 </tag-desc> <tag-name><literal>valid</literal></tag-name> <tag-desc> sets a time after which it should be checked that the file still exists with the same name; by default, 60 seconds </tag-desc> <tag-name><literal>off</literal></tag-name> <tag-desc> disables caching </tag-desc> </list> </para> <para> Example usage: <example> open_log_file_cache max=1000 inactive=20s valid=1m min_uses=2; </example> </para> </directive> </section> </module>