Impala配置HA-Nginx

Impala的高可用配置，官方的例子用的是Haproxy，考虑到nginx配置简单，使用人群广泛，再加上nginx1.9以后支持TCP的负载均衡，所以选用nginx。

nginx安装：yum install -y nginx，安装地址：192.168.101.22

Impala Daemon实例有三个：cdh-t-004,cdh-t-005,cdh-t-006

配置，编辑文件 /etc/nginx/nginx.conf：

# For more information on configuration, see:
#   * Official English Documentation: http://nginx.org/en/docs/
#   * Official Russian Documentation: http://nginx.org/ru/docs/

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;

# Load dynamic modules. See /usr/share/nginx/README.dynamic.
include /usr/share/nginx/modules/*.conf;

events {
    worker_connections  1024;
}

stream{
        upstream impalajdbc {
                hash $remote_addr consistent;
                server cdh-t-004:21050;
                server cdh-t-005:21050;
                server cdh-t-006:21050;
        }

        upstream impala {
                least_conn;
                server cdh-t-004:21000;
                server cdh-t-005:21000;
                server cdh-t-006:21000;
        }

        server {
                listen 25003;
                proxy_timeout 30s;
                proxy_pass impala;
        }

        server {
                listen 21051;
                proxy_timeout 30s;
                proxy_pass impalajdbc;
        }

}

校验配置文件是否正确：nginx -t

启动nginx：service nginx start

使用：

impala-shell  -i  192.168.101.22:25003

注： Impala守护进程Beeswax端口21000映射到Nginx 25003

        Impala守护进程HiveServer2端口21050映射到Nginx 21051

---

遇到的问题：

安装配置成功后，使用impala-shell时报错【2018/01/24 18:36:38 [crit] 10653#0: *13 connect() to 192.168.101.20:21000 failed (13: Permission denied) while connecting to upstream, client: 192.168.101.22, server: 0.0.0.0:25003, upstream: "192.168.101.20:21000", bytes from/to client:0/0, bytes from/to upstream:0/0】

分析：权限问题，impala主机无防火墙，需要修改SETLINUX配置

解决：执行命令【setenforce 0】，此命令修改的内容，在机器重启后会丢失，最好是修改配置文件【/etc/selinux/config】-> SELINUX=disabled，重启生效。