How to analyze nginx error log

1. Log introduction

There are two main types of nginx logs: access logs and error logs. The access log mainly records every request from the client to access nginx, and the format can be customized; the error log mainly records the log when the client accesses nginx and an error occurs, and the format does not support customization. Both logs can be optionally turned off.

Through the access log, you can get relevant information such as the user’s geographical origin, jump source, terminal usage, number of visits to a certain URL; through the error log, you can You can get the performance bottleneck of a certain service or server in the system, etc. Therefore, by making good use of logs, you can get a lot of valuable information.

2. Access log

[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'

'$ Requesst_Time $ Upstream_time_time

##113.140.15.90##$remote_user$time_local$request##200##$body_bytes_sent#$http_refererThe address of the backgroundTotal time of the entire requestDuring the request process,

##Variable name

Variable description

Examples

##$remote_addr

Client address

Client user name

-

Visit Time and time zone

##18/Jul/2012:17:00:01 0800

Requested URI

and

HTTP

Protocol"GET /pa/img/home/logo-alipay-t.png HTTP/1.1 "

##$http_host

Request address, that is, the address you enter in the browser (IP or domain name)

img.alipay .com

10.253.70.103

##$status

HTTPRequest Status

##200

##$upstream_status

##upstream

Status

The size of the file content sent to the client

547

Jump source

"https://cashier.alip

ay.com.../"

#$http_user_agent

User Terminal Agent

"Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; SV1; GTB7.0; .NET4.0C ;

##$ssl_protocol

SSLProtocol Version

TLSv1

$ssl_cipher

##Algorithms in exchange data

RC4-SHA

##$upstream_addr

upstream, that is, the host address that actually provides services

10.228.35.247:80

#$request_time

0.205

$upstream_response_time

upstream

Response time

0.002

##

Online example:

116.9.137.90 - [02/Aug/2012:14:47:12 0800] " GET /images/XX/20100324752729.png HTTP/1.1"img.alipay.com 200 200 2038 https://cashier.alipay.com/XX/PaymentResult.htm?payNo=XX&outBizNo=2012XX "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 10.228.21.237:80 0.198 0.001

Offline test ($http_referer)：

10.14.21.197 - - [14/Aug/2012:17:28:22 0800] "GET /spanner /watch/v1?--db=ztg-1&--mode=compare&--index=status&--option=&--cluster=whole&-F=2012/8/12-00:00:00&-T=+ 2880&-i=1&-n=0&_=1344936501292 HTTP/1.1" 200 94193 "http://spanner.alipay.net/optionFrame/history.html" "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.60 Safari/537.1"

##Remarks: $http_referer is related to redirection.

Offline test ($http_host):

Note: The value of $http_host is related to the value you enter in the browser.

3. Error log

（ on the browser ##upstream##"upstream sent invalid header while reading response header from upstream"The response header sent is invalid"upstream sent no valid HTTP/1.0 header while reading response header from upstream"The response header sent is invalid"client intended to send too large body","reopening logs"command

Error message	Error description
"upstream prematurely(premature) closed connection"	The exception that occurs when requesting uri is due to upstream It is caused by the user disconnecting when the response has not been returned to the user. It has no impact on the system and can be ignored
##"recv() failed (104: Connection reset by peer)"	1）server The number of concurrent connections exceeds its carrying capacity, and the server will Down drop some of the connections; （ 2）The client closed the browser, but the server is still sending data to the client; ( 3) Press Stop
##"(111: Connection refused) while connecting to upstream" When the user is connecting, if the user encounters the backend	upstream hangs up or fails, and you will receive this error
"(111: Connection refused) while reading response header from upstream"	When users read data after a successful connection, if the backend upstream hangs or is blocked, they will receive this error
"(111: Connection refused) while sending request to upstream"	# When ##Nginx and upstream are successfully connected and sending data, if the backend upstream hangs or is blocked, You will receive the error
##"(110: Connection timed out) while connecting to upstream "	##nginx Timeout when connecting to the following upstream
"(110: Connection timed out) while reading upstream"	nginx Timed out while reading the response from upstream
"(110: Connection timed out) while reading response header from upstream"	nginx Timeout while reading response headers from upstream
"(110: Connection timed out) while reading upstream"	nginx Timed out while reading response from upstream
"(104: Connection reset by peer) while connecting to upstream"	Send RST, reset the connection
upstream
upstream
is used to set the maximum value of client request content allowed to be accepted. The default value is 1M	clientThe body sent exceeds the set value
User sends kill -USR1
"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)"

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