1、日誌簡介
nginx日誌主要有兩種：訪問日誌和錯誤日誌。訪問日誌主要記錄客戶端訪問nginx的每一個請求，格式可以自定義；錯誤日誌主要記錄客戶端訪問nginx出錯時的日誌，格式不支持自定義。兩種日誌都可以選擇性關閉。
通過訪問日誌，你可以得到用戶地域來源、跳轉來源、使用終端、某個URL訪問量等相關信息；通過錯誤日誌，你可以得到系統某個服務或server的性能瓶頸等。因此，將日誌好好利用，你可以得到很多有價值的信息。
2、訪問日誌
[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';
變量名稱 | 變量描述 | 舉例說明 |
$remote_addr | 客戶端地址 | 113.140.15.90 |
$remote_user | 客戶端用戶名稱 | - |
$time_local | 訪問時間和時區 | 18/Jul/2012:17:00:01 +0800 |
$request | 請求的URI和HTTP協議 | "GET /pa/img/home/logo-alipay-t.png HTTP/1.1" |
$http_host | 請求地址，即瀏覽器中你輸入的地址（IP或域名） | img.alipay.com 10.253.70.103 |
$status | HTTP請求狀態 | 200 |
$upstream_status | upstream狀態 | 200 |
$body_bytes_sent | 發送給客戶端文件內容大小 | 547 |
$http_referer | 跳轉來源 | "https://cashier.alipay.com.../" |
$http_user_agent | 用戶終端代理 | "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; SV1; GTB7.0; .NET4.0C; |
$ssl_protocol | SSL協議版本 | TLSv1 |
$ssl_cipher | 交換數據中的算法 | RC4-SHA |
$upstream_addr | 後臺upstream的地址，即真正提供服務的主機地址 | 10.228.35.247:80 |
$request_time | 整個請求的總時間 | 0.205 |
$upstream_response_time | 請求過程中，upstream響應時間 | 0.002 |
線上實例：
116.9.137.90 - [02/Aug/2012:14:47:12 +0800] "GET /images/XX/20100324752729.png HTTP/1.1"img.alipay.com 200 200 2038 https://cashier.alipay.com/XX/PaymentResult.htm?payNo=XX&outBizNo=2012XX "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; Tablet PC 2.0; 360SE)" TLSv1 AES128-SHA 10.228.21.237:80 0.198 0.001
線下測試（$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%2F8%2F12-00%3A00%3A00&-T=%2B2880&-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"
備註：$http_referer和重定向有關。
線下測試（$http_host）：
備註：$http_host的值和你在瀏覽器裏輸入的值有關。
3、錯誤日誌
錯誤信息 | 錯誤說明 |
"upstream prematurely（過早的） closed connection" | 請求uri的時候出現的異常，是由於upstream還未返回應答給用戶時用戶斷掉連接造成的，對系統沒有影響，可以忽略 |
"recv() failed (104: Connection reset by peer)" | （1）服務器的併發連接數超過了其承載量，服務器會將其中一些連接Down掉； （2）客戶關掉了瀏覽器，而服務器還在給客戶端發送數據； （3）瀏覽器端按了Stop |
"(111: Connection refused) while connecting to upstream" | 用戶在連接時，若遇到後端upstream掛掉或者不通，會收到該錯誤 |
"(111: Connection refused) while reading response header from upstream" | 用戶在連接成功後讀取數據時，若遇到後端upstream掛掉或者不通，會收到該錯誤 |
"(111: Connection refused) while sending request to upstream" | Nginx和upstream連接成功後發送數據時，若遇到後端upstream掛掉或者不通，會收到該錯誤 |
"(110: Connection timed out) while connecting to upstream" | nginx連接後面的upstream時超時 |
"(110: Connection timed out) while reading upstream" | nginx讀取來自upstream的響應時超時
|
"(110: Connection timed out) while reading response header from upstream" | nginx讀取來自upstream的響應頭時超時 |
"(110: Connection timed out) while reading upstream" | nginx讀取來自upstream的響應時超時 |
"(104: Connection reset by peer) while connecting to upstream" | upstream發送了RST，將連接重置 |
"upstream sent invalid header while reading response header from upstream" | upstream發送的響應頭無效 |
"upstream sent no valid HTTP/1.0 header while reading response header from upstream" | upstream發送的響應頭無效 |
"client intended to send too large body" | 用於設置允許接受的客戶端請求內容的最大值，默認值是1M，client發送的body超過了設置值 |
"reopening logs" | 用戶發送kill -USR1命令 |
"gracefully shutting down", | 用戶發送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全都掛了 |
"SSL_do_handshake() failed" | SSL握手失敗 |
"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大小不夠等原因造成 |
"could not add new SSL session to the session cache while SSL handshaking" | ssl_session_cache大小不夠等原因造成 |
"send() failed (111: Connection refused)" |