Mac下配置Apache Httpd负载均衡(Load Balancer)之mod_jk

httpd版本: httpd-2.4.17
jk版本: tomcat-connectors-1.2.41

参考来源:

Apache (1) —— Mac下安装Apache Httpd到自定义路径（非/etc/apache2）

Apache (2) —— Mac 下安装多个Apache Tomcat实例

Working with mod_jk

How to Compile Tomcat mod_jk connector on Mac OS X Mavericks

Installing mod_jk for Apache 2.2 on Mac OS X 10.5 Leopard

Apache负载均衡配置

Apache学习之二、HTTPD的负载均衡

Apache配置反向代理、负载均衡和集群(mod_proxy方式)

准备

首先我们参照下面两篇文章配置好httpd和两个Tomcat实例

• Apache (1) —— Mac下安装Apache Httpd到自定义路径（非/etc/apache2）

• Apache (2) —— Mac 下安装多个Apache Tomcat实例

其中Tomcat的两个实例node-a和node-b分别存放与"./servers/cluster/tomcat/node-a"和"/servers/cluster/tomcat/node-b"下

对应的配置分别为：

• Server Port: 8015 与 8025
• Connector: 8081 与 8082
• AJP: 8019 与 8029

另分别为连个实例添加jvmRoute的配置

• node-a

    <Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat1">

• node-b

    <Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat2">

注意：不要忘记修改供测试的页面特征

配置httpd负载均衡（Load Balancer）

httpd负载均衡Tomcat的方式主要可以分为两类

1. httpd自带的mod_proxy
2. Tomcat提供了专门的JK插件来负责Tomcat和HTTP服务器的通信mod_jk

*注意 本篇文章主要关注第二类配置

首先编译

在Apache的网站上下载tomcat-connectors-1.2.41，然后解压。

运行命令编译

$ cd native
$ ./configure CFLAGS='-arch x86_64' APXSLDFLAGS='-arch x86_64' --with-apxs=/usr/sbin/apxs
$ make
$ sudo make install

*注意 --with-apxs需要指向目标节点的apxs

此处我本地的路径为

/Users/Richard/Documents/Dev/servers/cluster/httpd/node-a/bin/apxs

如果执行正常不出错，末尾几行的输出为

...
config.status: creating common/list.mk
config.status: creating common/jk_types.h
config.status: creating common/config.h
config.status: executing depfiles commands
config.status: executing libtool commands

然后"./native"下运行make

期间会出现warning，可以暂时忽略不影响

jk_lb_worker.c:1397:36: warning: address of array'p->worker->session_cookie_path' will always evaluate to 'true'[-Wpointer-bool-conversion]if (p->worker->session_cookie_path && *p->worker->se...~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~ ~~

make执行正常的最后几行输出为

...
Making all in common
make[1]: Nothing to be done for `all'.
Making all in apache-2.0
make[1]: Nothing to be done for `all'.

make install如果在非sudo状态下，最后会出现错误

...
install: /Users/Richard/Documents/Dev/servers/cluster/httpd/node-a/modules/mod_jk.so: Permission denied
apxs:Error: Command failed with rc=4653056
.
make[1]: *** [install_dynamic] Error 1
make: *** [install-recursive] Error 1

sudo运行make install

...
libtool: install: ranlib /Users/Richard/Documents/Dev/servers/cluster/httpd/node-a/modules/mod_jk.a
chmod 755 /Users/Richard/Documents/Dev/servers/cluster/httpd/node-a/modules/mod_jk.soPlease be sure to arrange /Users/Richard/Documents/Dev/servers/cluster/httpd/node-a/conf/httpd.conf...make[2]: Nothing to be done for `install-exec-am'.
make[2]: Nothing to be done for `install-data-am'.

配置mod_jk

在node-a下新建文件夹"other"，并创建文件workers.properties

# Define two status worker:
# - jk-status for read-only use
# - jk-manager for read/write use
worker.list=jk-status
worker.jk-status.type=status
worker.jk-status.read_only=true  worker.list=jk-manager
worker.jk-manager.type=status  # We define a load balancer worker
# with name "balancer"
worker.list=balancer
worker.balancer.type=lb
worker.balancer.error_escalation_time=0
worker.balancer.max_reply_timeouts=10
worker.balancer.sticky_session=true
worker.balancer.sticky_session_force=true    # Now we add members to the load balancer First member is "tomcat1", most attributes are inherited from the template "worker.template".
worker.balancer.balance_workers=tomcat1
worker.tomcat1.reference=worker.template
worker.tomcat1.host=127.0.0.1
worker.tomcat1.port=8019
worker.tomcat1.activation=A  # Second member is "tomcat2", most attributes are inherited from the template "worker.template".
worker.balancer.balance_workers=tomcat2
worker.tomcat2.reference=worker.template
worker.tomcat2.host=127.0.0.1
worker.tomcat2.port=8029
worker.tomcat2.activation=A  # Finally we put the parameters
worker.template.type=ajp13
worker.template.socket_connect_timeout=5000
worker.template.socket_keepalive=true
worker.template.ping_mode=A
worker.template.ping_timeout=10000
worker.template.connection_pool_minsize=0
worker.template.connection_pool_timeout=600
worker.template.reply_timeout=300000
worker.template.recovery_options=3  

*注意上面的host配置都是127.0.0.1，会影响我们下面的测试

并同时在"./node-a/other/"下创建文件uriworkermap.properties

/*.do=balancer
/*.jsp=balancer  #/*.gif=balancer
#/*.jpg=balancer
#/*.png=balancer
#/*.css=balancer
#/*.js=balancer
#/*.htm=balancer
#/*.html=balancer
#/*.txt=balancer  # Optionally filter out all .jpeg files inside that context
# For no mapping the url has to start with exclamation (!)  !/servlets-examples/*.jpeg=lb  #
# Mount jkstatus to /jkmanager
# For production servers you will need to
# secure the access to the /jkmanager url
#
/jk-manager=jk-manager
/jk-status=jk-status  

最后

为httpd.conf，添加配置

# 加载jk配置文件
Include conf/mod_jk.conf 

测试

重新启动httpd，并用浏览器访问"localhost:81"，提示"Service Unavailable"错误

查看"./node-a/log"目录下"mod_jk.log"文件

[Wed Dec 09 15:00:31.403 2015] [13735:4417540096] [info] get_most_suitable_worker::jk_lb_worker.c (1119): all workers are in error state for session QUMQZVRPS1-4MX593EAOD71Y6YAFXUP1-U734UPHI-1
[Wed Dec 09 15:00:31.403 2015] [13735:4417540096] [info] service::jk_lb_worker.c (1664): All tomcat instances failed, no more workers left (attempt=1, retry=1)
[Wed Dec 09 15:00:31.403 2015] [13735:4417540096] [info] service::jk_lb_worker.c (1675): All tomcat instances are busy or in error state
[Wed Dec 09 15:00:31.403 2015] [13735:4417540096] [error] service::jk_lb_worker.c (1680): All tomcat instances failed, no more workers left
[Wed Dec 09 15:00:31.403 2015] [13735:4417540096] [info] jk_handler::mod_jk.c (2991): Service error=0 for worker=balancer

尝试访问

127.0.0.1:81

得到正常结果

这样就完成一个以httpd单节点为负载均衡器分发到不同Tomcat的简单架构。

*扩展

• 如果将host改为"localhost"是否能正常访问?
• 与另一篇中用httpd自带lb的方式不同映射的路径（"./test"），这里是根目录，需要如何配置达到相同效果?
• 这里测试结果可以正常显示样式和图片，是什么配置起的作用？