Changing SSH port for dynamic inventory script in Ansible

If you have to write dynamic inventory script in Ansible, but need to use SSH port which is not 22, there is example output of the script output:

{"databases":{
    "hosts":["127.0.0.1"],
    "vars":{
        "ansible_ssh_port":2222
        }
    }
}

Ansible freezes during start

If Ansible stops for several minutes or so during start without any messages, check if it calls your inventory script, because it might query for additional options using --host parameter and if there are a lot of hosts, it may take some time.

It can be easily fixed by adding this to JSON root:

    "_meta" : {
       "hostvars" : {
       }
    }

More about it here.

Storing sessions in Redis with Spring Boot

Tomcat has nice support to use Redis for session replication with this awesome library. However Spring Boot launches embedded Tomcat, so there is no traditional XML configuration, it is still super easy to change default manager to use Redis for session replication, just define containerCustomizer bean, like:

@Configuration
@EnableAutoConfiguration
@ComponentScan
public class App {
  public App() {
  }

  @Bean
  public EmbeddedServletContainerCustomizer containerCustomizer(){
    return factory -> {
      TomcatEmbeddedServletContainerFactory containerFactory = (TomcatEmbeddedServletContainerFactory) factory;
      containerFactory.addContextValves(new RedisSessionHandlerValve());
      containerFactory.setTomcatContextCustomizers(Arrays.asList(context -> {
        context.setSessionTimeout(30);
        context.setManager(new RedisSessionManager(){{
          setHost("redis.server.com");
        }});
      }));
    };
  }

  public static void main(String[] args) throws Exception {
    SpringApplication.run(App.class, args);
  }
}

(this is syntax with new shiny Java 8 lambdas, but with few additional boring types it should compile in old Javas too).

Working around grails.serverURL redirect in Grails 2

The most annoying issue with Grails 2 migration is that it requires redirection to grails.serverURL when it is specified. This property is needed if there are absolute links in application (in emails, for example).
First problem that I had with it, was after deploying application to test environment. We deploy production version, so all redirects became redirects to production, this could be solved by externalizing Grails configuration.
Second problem was more severe. We have following setup: load balancer with two nodes behind it. Our deployment script takes first node down, deploys, runs smoke tests, releases first node, takes second node down, deploys, smoke tests, releases.
So basically, production URL is load balancer's entry point, and when smoke tests run on node which is down it is never redirected to tested server (because it is down and it is behind load balancer), so every redirect (after spring security login, for example), breaks tests flow.
After some digging around, I found the best option is to abandon grails.serverURL - which is totally unusable now, and add to email link generation my own parameter from externalized Grails configuration (for each environment). This is sad as createLink with absolute parameter was great function and it didn't required dragging custom parameters.
That is how it is now.
What I would love to see in the future is grails.serverURL is used ONLY in all links generated with absolute:true and nowhere else, but all redirects work as if grails.serverURL not specified at all.

InvalidClassException: GrailsUser and plugin upgrade

Recently when I tried to deploy new version of application on live server without downtime, I got error:

2011-10-14 11:02:52,058 [Tribes-Task-Receiver-4] ERROR org.apache.catalina.ha.session.DeltaManager- Manager [localhost#]: Unable to receive message through TCP channel
java.io.InvalidClassException: org.codehaus.groovy.grails.plugins.springsecurity.GrailsUser; local class incompatible: stream classdesc serialVersionUID = -3114204362518930756, local class serialVersionUID =
        at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:579)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1600)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1513)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1600)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1513)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1749)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1963)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1887)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1963)

Basically, error is trivial, just some Spring security classes are not versioned and cluster can't synchronize users data. Fortunately, as I have found out, no hacking is needed and it can be easily fixed by upgrading spring-security-core plugin to the latest version.

To upgrade to latest version, just uninstall plugin and install it again, like:

grails uninstall-plugin spring-security-core
grails install-plugin spring-security-core