nginx模块开发（18）

1、日志简介

nginx日志主要有两种：访问日志和错误日志。访问日志主要记录客户端访问nginx的每一个请求，格式可以自定义；错误日志主要记录客户端访问nginx出错时的日志，格式不支持自定义。两种日志都可以选择性关闭。

通过访问日志，你可以得到用户地域来源、跳转来源、使用终端、某个URL访问量等相关信息；通过错误日志，你可以得到系统某个服务或server的性能瓶颈等。因此，将日志好好利用，你可以得到很多有价值的信息。

2、访问日志

[Access.log]

log_format main '$remote_addr $remote_user [$time_local] "$request" $http_host '

'$status $upstream_status $body_bytes_sent "$http_referer" '

'"$http_user_agent" $ssl_protocol $ssl_cipher $upstream_addr '

'$request_time $upstream_response_time';

变量名称	变量描述	举例说明
$remote_addr	客户端地址	1.1.1.1
$remote_user	客户端用户名称	-
$time_local	访问时间和时区	18/Jul/2012:17:00:01 +0800
$request	请求的URI和HTTP协议	"GET /XX HTTP/1.1"
$http_host	请求地址，即浏览器中你输入的地址（IP或域名）	hello.world.com 2.2.2.2
$status	HTTP请求状态	200
$upstream_status	upstream状态	200
$body_bytes_sent	发送给客户端文件内容大小	547
$http_referer	跳转来源	"https://hello.cj.com.../"
$http_user_agent	用户终端代理	"Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; SV1; GTB7.0; .NET4.0C;
$ssl_protocol	SSL协议版本	TLSv1
$ssl_cipher	交换数据中的算法	RC4-SHA
$upstream_addr	后台upstream的地址，即真正提供服务的主机地址	3.3.3.3:80
$request_time	整个请求的总时间	0.205
$upstream_response_time	请求过程中，upstream响应时间	0.002

线上实例：

1.1.1.1 - [02/Aug/2012:14:47:12 +0800] "GET /images/XX/20100324752729.png HTTP/1.1" hello.world.com 200 200 2038https://hello.cj.com/XX/PaymentResult.htm "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; Tablet PC 2.0; 360SE)" TLSv1 AES128-SHA 3.3.3.3:80 0.198 0.001

3、错误日志

错误信息	错误说明
"upstream prematurely（过早的）closed connection"	upstream关闭了链接造成的
"recv() failed (104: Connection reset by peer)"	（1）服务器的并发连接数超过了其承载量，服务器会将其中一些连接Down掉；（2）客户关掉了浏览器，而服务器还在给客户端发送数据；（3）浏览器端按了Stop
"(111: Connection refused) while connecting to upstream"	用户在连接时，若遇到后端upstream挂掉或者不通，会收到该错误
"(111: Connection refused) while reading response header from upstream"	用户在连接成功后读取数据时，若遇到后端upstream挂掉或者不通，会收到该错误
"(111: Connection refused) while sending request to upstream"	Nginx和upstream连接成功后发送数据时，若遇到后端upstream挂掉或者不通，会收到该错误
"(110: Connection timed out) while connecting to upstream"	nginx连接后面的upstream时超时
"(110: Connection timed out) while reading upstream"	nginx读取来自upstream的响应时超时
"(110: Connection timed out) while reading response header from upstream"	nginx读取来自upstream的响应头时超时
"(110: Connection timed out) while reading upstream"	nginx读取来自upstream的响应时超时
"(104: Connection reset by peer) while connecting to upstream"	upstream发送了RST，将连接重置
"upstream sent invalid header while reading response header from upstream"	upstream发送的响应头无效
"upstream sent no valid HTTP/1.0 header while reading response header from upstream"	upstream发送的响应头无效
"client intended to send too large body"	用于设置允许接受的客户端请求内容的最大值，默认值是1M，client发送的body超过了设置值
"reopening logs"	用户发送kill -USR1命令
"gracefully shutting down",	用户发送kill -WINCH命令
"no servers are inside upstream"	upstream下未配置server
"no live upstreams while connecting to upstream"	upstream下的server全都挂了
"SSL_do_handshake() failed"	SSL握手失败
"SSL_write() failed (SSL:) while sending to client"
"(13: Permission denied) while reading upstream"
"(98: Address already in use) while connecting to upstream"
"(99: Cannot assign requested address) while connecting to upstream"
"ngx_slab_alloc() failed: no memory in SSL session shared cache"	ssl_session_cache大小不够等原因造成
"could not add new SSL session to the session cache while SSL handshaking"	ssl_session_cache大小不够等原因造成
"send() failed (111: Connection refused)"