What's the recommended way to set networkaddress.cache.ttl in Elastic Beanstalk?

问题

I need to set Java's DNS cache TTL (networkaddress.cache.ttl) for an Amazon Elastic Beanstalk app running in Tomcat 8. Because EB can start and stop server instances at any time, I can't simply edit a Tomcat config file and the server and expect the change to persist.

I tried setting the networkaddress.cache.ttl and sun.net.inetaddr.ttl environment variables, but those had no effect. Amazon says calling java.security.Security.setProperty("networkaddress.cache.ttl" , "60"); "will not work if you run your application inside of Tomcat" (http://aws.amazon.com/articles/4035). What's a good way to set the TTL?

回答1:

The problem is that I was doing it wrong. Setting the sun.net.inetaddr.ttl environment variable works. You can do this in your Elastic Beakstalk config file:

option_settings:
    - namespace: aws:elasticbeanstalk:application:environment
      option_name: sun.net.inetaddr.ttl
      value: 60

60 seconds is the value recommended by Amazon

Another option that seems a little nicer to me is to create and use a java.security file:

option_settings:
    - namespace: aws:elasticbeanstalk:application:environment
      option_name: java.security.properties
      value: /etc/myapp/java.security
container_commands:
    00create_config_dir:
        command: 'mkdir -p /etc/myapp'
        ignoreErrors: true
    01create_java_security_file:
        command: 'echo "networkaddress.cache.ttl=60" > /etc/myapp/java.security'
        ignoreErrors: true

回答2:

If you are using spring framework, following is what I did to set the networkaddress.cache.ttl at the time of application initialisation.

Define a new Java class as follows.

package com.example.util;
public class SecurityManager {
  public SecurityManager() {
    java.security.Security.setProperty("networkaddress.cache.ttl", "60");
  }
}

Ask spring framework to instantiate the object of above class as a singleton at the time on spring container creation.

<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

  <bean id="securityManager" 
    class="com.example.util.SecurityManager" scope="singleton" />

</beans>

来源：https://stackoverflow.com/questions/29579589/whats-the-recommended-way-to-set-networkaddress-cache-ttl-in-elastic-beanstalk

标签

java

Tomcat

amazon-elastic-beanstalk

tomcat8