nginx内置变量(嵌入变量)有哪些

nginx中使用变量可以更加灵活。

自定义变量

自定义变量(放在location还是server中都可以)：

set $myname "zhangsan"; #声明变量
return 502 $myname;

嵌入变量有哪些

Embedded Variables
The ngx_http_core_module module supports embedded variables with names matching the Apache Server variables. First of all, these are variables representing client request header fields, such as $http_user_agent, $http_cookie, and so on. Also there are other variables:

$arg_name
argument name in the request line
$args
arguments in the request line
$binary_remote_addr
client address in a binary form, value’s length is always 4 bytes for IPv4 addresses or 16 bytes for IPv6 addresses
$body_bytes_sent
number of bytes sent to a client, not counting the response header; this variable is compatible with the “%B” parameter of the mod_log_config Apache module
$bytes_sent
number of bytes sent to a client (1.3.8, 1.2.5)
$connection
connection serial number (1.3.8, 1.2.5)
$connection_requests
current number of requests made through a connection (1.3.8, 1.2.5)
$content_length
“Content-Length” request header field
$content_type
“Content-Type” request header field
$cookie_name
the name cookie
$document_root
root or alias directive’s value for the current request
$document_uri
same as $uri
$host
in this order of precedence: host name from the request line, or host name from the “Host” request header field, or the server name matching a request
$hostname
host name
$http_name
arbitrary request header field; the last part of a variable name is the field name converted to lower case with dashes replaced by underscores
$https
“on” if connection operates in SSL mode, or an empty string otherwise
$is_args
“?” if a request line has arguments, or an empty string otherwise
$limit_rate
setting this variable enables response rate limiting; see limit_rate
$msec
current time in seconds with the milliseconds resolution (1.3.9, 1.2.6)
$nginx_version
nginx version
$pid
PID of the worker process
$pipe
“p” if request was pipelined, “.” otherwise (1.3.12, 1.2.7)
$proxy_protocol_addr
client address from the PROXY protocol header (1.5.12)
The PROXY protocol must be previously enabled by setting the proxy_protocol parameter in the listen directive.

$proxy_protocol_port
client port from the PROXY protocol header (1.11.0)
The PROXY protocol must be previously enabled by setting the proxy_protocol parameter in the listen directive.

$proxy_protocol_server_addr
server address from the PROXY protocol header (1.17.6)
The PROXY protocol must be previously enabled by setting the proxy_protocol parameter in the listen directive.

$proxy_protocol_server_port
server port from the PROXY protocol header (1.17.6)
The PROXY protocol must be previously enabled by setting the proxy_protocol parameter in the listen directive.

$query_string
same as $args
$realpath_root
an absolute pathname corresponding to the root or alias directive’s value for the current request, with all symbolic links resolved to real paths
$remote_addr
client address
$remote_port
client port
$remote_user
user name supplied with the Basic authentication
$request
full original request line
$request_body
request body
The variable’s value is made available in locations processed by the proxy_pass, fastcgi_pass, uwsgi_pass, and scgi_pass directives when the request body was read to a memory buffer.

$request_body_file
name of a temporary file with the request body
At the end of processing, the file needs to be removed. To always write the request body to a file, client_body_in_file_only needs to be enabled. When the name of a temporary file is passed in a proxied request or in a request to a FastCGI/uwsgi/SCGI server, passing the request body should be disabled by the proxy_pass_request_body off, fastcgi_pass_request_body off, uwsgi_pass_request_body off, or scgi_pass_request_body off directives, respectively.

$request_completion
“OK” if a request has completed, or an empty string otherwise
$request_filename
file path for the current request, based on the root or alias directives, and the request URI
$request_id
unique request identifier generated from 16 random bytes, in hexadecimal (1.11.0)
$request_length
request length (including request line, header, and request body) (1.3.12, 1.2.7)
$request_method
request method, usually “GET” or “POST”
$request_time
request processing time in seconds with a milliseconds resolution (1.3.9, 1.2.6); time elapsed since the first bytes were read from the client
$request_uri
full original request URI (with arguments)
$scheme
request scheme, “http” or “https”
$sent_http_name
arbitrary response header field; the last part of a variable name is the field name converted to lower case with dashes replaced by underscores
$sent_trailer_name
arbitrary field sent at the end of the response (1.13.2); the last part of a variable name is the field name converted to lower case with dashes replaced by underscores
$server_addr
an address of the server which accepted a request
Computing a value of this variable usually requires one system call. To avoid a system call, the listen directives must specify addresses and use the bind parameter.

$server_name
name of the server which accepted a request
$server_port
port of the server which accepted a request
$server_protocol
request protocol, usually “HTTP/1.0”, “HTTP/1.1”, or “HTTP/2.0”
$status
response status (1.3.2, 1.2.2)
$tcpinfo_rtt, $tcpinfo_rttvar, $tcpinfo_snd_cwnd, $tcpinfo_rcv_space
information about the client TCP connection; available on systems that support the TCP_INFO socket option
$time_iso8601
local time in the ISO 8601 standard format (1.3.12, 1.2.7)
$time_local
local time in the Common Log Format (1.3.12, 1.2.7)
$uri
current URI in request, normalized
The value of $uri may change during request processing, e.g. when doing internal redirects, or when using index files.

官网文档地址-Embedded Variables(嵌入/内置变量)：
http://nginx.org/en/docs/http/ngx_http_core_module.html#variables