解决Linux下ArcGIS Server的Tomcat不稳定问题，nginx配置反向代理时的一个小问题

背景：Linux上的ArcGIS Server的Tomcat进程基本上一天崩溃一次，全天在处理rest请求，压力较大。而SOM与SOC压力较小

解决方案：使用多个Web Service，加入另一台nginx反向代理服务器的upstream。

遇到问题：使用了反向代理的缘故，web service handler必须要用arcgis/rest方式暴露服务。所以如何配置tomcat，便成了一个比较重要的问题。

问题处理：在tomcat配置文件server.xml的host标签中加入Context，指明应用根目录。

<Host name="localhost"  appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context path="/arcgis/rest" docBase="./arcgis/rest" reloadable="true"/>
<!-- SingleSignOn valve, share authentication between web applications
Documentation at: /docs/config/valve.html -->
<!--
<Valve className="org.apache.catalina.authenticator.SingleSignOn" />
-->

<!-- Access log processes all example.
Documentation at: /docs/config/valve.html
Note: The pattern used is equivalent to using pattern="common" -->
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log." suffix=".txt"
pattern="%h %l %u %t "%r" %s %b" />

</Host>

这样，就可以像访问arcgis server一样，访问localhost:8080/arcgis/rest了(注意修改每个REST Service Handler的SOM地址)。

在nginx中，配置为：

worker_processes auto;
events {
worker_connections  1024;
use epoll;
}
http {
include       mime.types;
default_type  application/octet-stream;
access_log off;
sendfile        on;
keepalive_timeout  65;
upstream gpsarcgis{
server SERVER1:6080 max_fails=3;
server SERVER2:6080 max_fails=3;
server Server3:6080 max_fails=3;
server Server4:8081 max_fails=3 weight=3;
server Server5:8081 max_fails=3 weight=3;
server Server6 :8081 max_fails=3 weight=3;
}
server {
listen       6080;
server_name  IP1 IP2;
charset utf-8;
location / {
proxy_pass http://gpsarcgis; proxy_set_header   Host             $host;
proxy_set_header   X-Real-IP        $remote_addr;
proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
proxy_next_upstream error timeout invalid_header http_500 http_504 http_404;
}
error_page   500 502 503 504  /50x.html;
location = /50x.html {
root   html;
}
}
}

前三个为ArcGIS Server原始地址和端口，后面为tomcat。打上双保险，舒服多了！