#+TITLE 判断是否支持Http keep-alive
方法一
没有开启Nginx Keepalive
curl -Iv https://beta.company/ --next https://beta.company/ * Trying 127.0.0.1... * TCP_NODELAY set * Connected to beta.company (127.0.0.1) port 443 (#0) * TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 * Server certificate: beta.company * Server certificate: TrustAsia DV SSL CA - G5 * Server certificate: VeriSign Class 3 Public Primary Certification Authority - G5 > HEAD / HTTP/1.1 > Host: beta.company > User-Agent: curl/7.51.0 > Accept: */* > < HTTP/1.1 302 Found HTTP/1.1 302 Found < Server: nginx/1.9.3 Server: nginx/1.9.3 < Date: Mon, 10 Apr 2017 04:57:35 GMT Date: Mon, 10 Apr 2017 04:57:35 GMT < Content-Length: 0 Content-Length: 0 < Connection: close Connection: close < Access-Control-Allow-Origin: * Access-Control-Allow-Origin: * < Access-Control-Allow-Methods: POST, GET, OPTIONS Access-Control-Allow-Methods: POST, GET, OPTIONS < Access-Control-Max-Age: 1000 Access-Control-Max-Age: 1000 < Set-Cookie: SESSION=3a52bf55-385e-46af-895d-b078d76c1145; Path=/; Secure; HttpOnly Set-Cookie: SESSION=3a52bf55-385e-46af-895d-b078d76c1145; Path=/; Secure; HttpOnly < Location: https://beta.company/login Location: https://beta.company/login < Content-Language: en-US Content-Language: en-US < * Curl_http_done: called premature == 0 * Closing connection 0 * Hostname beta.company was found in DNS cache * Trying 127.0.0.1... * TCP_NODELAY set * Connected to beta.company (127.0.0.1) port 443 (#1) * SSL re-using session ID * TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 * Server certificate: beta.company * Server certificate: TrustAsia DV SSL CA - G5 * Server certificate: VeriSign Class 3 Public Primary Certification Authority - G5 > HEAD / HTTP/1.1 > Host: beta.company > User-Agent: curl/7.51.0 > Accept: */* > < HTTP/1.1 302 Found < Server: nginx/1.9.3 < Date: Mon, 10 Apr 2017 04:57:36 GMT < Content-Length: 0 < Connection: close < Access-Control-Allow-Origin: * < Access-Control-Allow-Methods: POST, GET, OPTIONS < Access-Control-Max-Age: 1000 < Set-Cookie: SESSION=950715f2-b8dc-4aad-a91e-68cc2b70aa98; Path=/; Secure; HttpOnly < Location: https://beta.company/login < Content-Language: en-US < * Curl_http_done: called premature == 0 * Closing connection 1
开启了Nginx Keepalive
curl -Iv https://beta.company/ --next https://beta.company/ * Trying 127.0.0.1... * TCP_NODELAY set * Connected to beta.company (127.0.0.1) port 443 (#0) * TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 * Server certificate: beta.company * Server certificate: TrustAsia DV SSL CA - G5 * Server certificate: VeriSign Class 3 Public Primary Certification Authority - G5 > HEAD / HTTP/1.1 > Host: beta.company > User-Agent: curl/7.51.0 > Accept: */* > < HTTP/1.1 302 Found HTTP/1.1 302 Found < Server: nginx/1.9.3 Server: nginx/1.9.3 < Date: Mon, 10 Apr 2017 05:06:42 GMT Date: Mon, 10 Apr 2017 05:06:42 GMT < Content-Length: 0 Content-Length: 0 < Connection: keep-alive Connection: keep-alive < Access-Control-Allow-Origin: * Access-Control-Allow-Origin: * < Access-Control-Allow-Methods: POST, GET, OPTIONS Access-Control-Allow-Methods: POST, GET, OPTIONS < Access-Control-Max-Age: 1000 Access-Control-Max-Age: 1000 < Set-Cookie: SESSION=9ddf4115-654a-40a1-8894-8975b334a5dc; Path=/; Secure; HttpOnly Set-Cookie: SESSION=9ddf4115-654a-40a1-8894-8975b334a5dc; Path=/; Secure; HttpOnly < Location: https://beta.company/login Location: https://beta.company/login < Content-Language: en-US Content-Language: en-US < * Curl_http_done: called premature == 0 * Connection #0 to host beta.company left intact * Found bundle for host beta.company: 0x7fe3cac0c7f0 [can pipeline] * Re-using existing connection! (#0) with host beta.company * Connected to beta.company (127.0.0.1) port 443 (#0) > HEAD / HTTP/1.1 > Host: beta.company > User-Agent: curl/7.51.0 > Accept: */* > < HTTP/1.1 302 Found < Server: nginx/1.9.3 < Date: Mon, 10 Apr 2017 05:06:43 GMT < Content-Length: 0 < Connection: keep-alive < Access-Control-Allow-Origin: * < Access-Control-Allow-Methods: POST, GET, OPTIONS < Access-Control-Max-Age: 1000 < Set-Cookie: SESSION=9647d698-1779-4e09-8080-fcc7770e5701; Path=/; Secure; HttpOnly < Location: https://beta.company/login < Content-Language: en-US < * Curl_http_done: called premature == 0 * Connection #0 to host beta.company left intact
它们的区别:
diff /tmp/keep.txt /tmp/no-keep.txt
< * Connection #0 to host beta.company left intact < * Found bundle for host beta.company: 0x7fe3cac0c7f0 [can pipeline] < * Re-using existing connection! (#0) with host beta.company < * Connected to beta.company (127.0.0.1) port 443 (#0) --- > * Closing connection 0 > * Hostname beta.company was found in DNS cache > * Trying 127.0.0.1... > * TCP_NODELAY set > * Connected to beta.company (127.0.0.1) port 443 (#1) > * SSL re-using session ID > * TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 > * Server certificate: beta.company > * Server certificate: TrustAsia DV SSL CA - G5 > * Server certificate: VeriSign Class 3 Public Primary Certification Authority - G5 50c56 < < Date: Mon, 10 Apr 2017 05:06:43 GMT --- > < Date: Mon, 10 Apr 2017 05:08:17 GMT 52c58 < < Connection: keep-alive --- > < Connection: close
可以看到，开启了Keep alive的链接信息为 re-useing existing connection 而没有 keep alive 的话，则是 Connected to 。
方法二
直接查看 Chrome 浏览器的调试中的请求头和响应头
Request URL:https://beta.company/login Request Method:GET Status Code:200 OK Remote Address:127.0.0.1:443 Referrer Policy:origin Response Headers Access-Control-Allow-Methods:POST, GET, OPTIONS Access-Control-Allow-Origin:* Access-Control-Max-Age:1000 Connection:close Content-Encoding:gzip Content-Language:en-US Content-Type:text/html;charset=utf-8 Date:Mon, 10 Apr 2017 05:00:39 GMT Server:nginx/1.9.3 Transfer-Encoding:chunked Vary:Accept-Encoding Request Headers view source Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Accept-Encoding:gzip, deflate, sdch, br Accept-Language:en-US,en;q=0.8,zh-CN;q=0.6,zh;q=0.4 Cache-Control:no-cache Connection:keep-alive
可以看到，客户端浏览器发送了 Connection:keep-alive 的请求头，但服务器响应却是 Connection:close 这表示服务器端不支持 http keep-alive 。如果服务器端开启支持的话，它返回的是 Connection:keep-alive 。