Unable to get the hostName or IP address of the server when starting WSO2 Products

Today I faced an issue when a wso2 server that needed restarting did not start up, after shutting down due to the error

{org.apache.synapse.ServerConfigurationInformation} -  Unable to get the hostName or IP address of the server {org.apache.synapse.ServerConfigurationInformation}
java.net.UnknownHostException: <hostname> : <hostname> : Name or service not known
at java.net.InetAddress.getLocalHost(InetAddress.java:1473)
at org.apache.synapse.ServerConfigurationInformation.initServerHostAndIP(ServerConfigurationInformation.java:215)
at org.apache.synapse.ServerConfigurationInformation.<init>(ServerConfigurationInformation.java:66)
at org.apache.synapse.ServerConfigurationInformationFactory.createServerConfigurationInformation(ServerConfigurationInformationFactory.java:48)
at org.wso2.carbon.mediation.initializer.ServiceBusInitializer.initESB(ServiceBusInitializer.java:365)
at org.wso2.carbon.mediation.initializer.ServiceBusInitializer.activate(ServiceBusInitializer.java:182)

The issue in my case was that it was not a wso2 bug. It is an issue with the machine.

The OS I was using was ubuntu. The issue was that the hostname was not correctly set.


The easy way  - temporary fix

1) Run the following command. (assuming the hostname you want to set is abc001)

                    #    hostname abc001

2) To verify the hostname just run the following command

                           # hostname


it should output the hostname that we set as the output.


Proper fix

1) We need to fix this properly. In that case, we need to change the /sysconfig/network file.

open this file as sudo or super user, and change the hostname in that file to be the hostname you require.

                           HOSTNAME=abc001

2) Then you need to update the etc/hosts file, to reflect this change. you should map the entry

                       127.0.0.1 abc001 

                               or
                      <local-ip> abc001

3) After that you need to restart the network service.

                   #service network restart
                                       or 
                   #/etc/init.d/network restart

4) Then verify the hostname has been set by running the command

                    # hostname


References

1) http://www.howtogeek.com/50631/how-to-change-your-linux-hostname-without-rebooting/