Backend hostname is changed in the junction configuration

Answer

When the junction is created it does a reverse look up of the IP address to resolve it to its hostname. It maps this to the primary hostname which is represented as the first one defined in the hosts file. The primary hostname is then used in the junction configuration XML file.

An exception to the above is the fully qualified domain name (FQDN). FQDN is always used in the junction configuration file as defined by the junction creation command even if it is not the primary hostname.

Notice! It is important to understand that above rules apply whenever junction configuration is modified and not just during the creation time of the junction. With the ISAM appliance a junction configuration will be rewritten when the Save button is clicked in the junction edit view even no modifications has been done in the junction settings.

Examples below show some cases of the hostname being changed in the junction XML configuration.


Test case 1

The following is defined in the /etc/hosts file:
192.168.10.10    jupiter mars

Create a junction using a hostname alias for the backend server name.

pdadmin sec_master> server task default-webseald-nutshell create -t tcp -h mars /hostaliastest


Result

The junction xml for the /hostaliastest junction shows jupiter for the backend hostname instead of mars as given in the junction creation command.

Excerpt of the junction XML:
...
    <HOST>jupiter</HOST>
    <PORT>80</PORT>
    <VIRTHOSTNM>jupiter</VIRTHOSTNM>
...


Test case 2a

Modify /etc/hosts file by adding a new hostname on front of the previous hostnames:
192.168.10.10   earth jupiter mars

"Modify" previously created junction ( test case 1 ). In the ISAM appliance it will be enough to open a junction edit view and click the Save button.

pdadmin sec_master> server task default-webseald-nutshell create -t tcp -h mars /hostaliastest -f


Result:

The junction xml shows that hostname has been changed. The original hostname jupiter in the junction XML is now changed to earth.

Excerpt of the junction XML:
...
    <HOST>earth</HOST>
    <PORT>80</PORT>
    <VIRTHOSTNM>earth</VIRTHOSTNM>
...


Test case 2b

Modify /etc/hosts file by adding a new hostname on front of the previous hostnames and add another IP with hostnames:
192.168.10.10   earth jupiter mars
192.168.10.11   venus mercury

Modify previously created junction ( test case 1 ) by adding a second backend server to the junction configuration.

pdadmin sec_master> server task default-webseald-nutshell add -h mercury /hostaliastest


Result:

The junction xml shows that hostname has been changed. The original hostname jupiter in the junction XML is now changed to earth. The second backend server added to the junction configuration is also changed from mercury to venus.

Excerpt of the junction XML:
...
    <HOST>earth</HOST>
    <PORT>80</PORT>
    <VIRTHOSTNM>earth</VIRTHOSTNM>
...

    <HOST>venus</HOST>
    <PORT>80</PORT>
    <VIRTHOSTNM>venus</VIRTHOSTNM>
...


Test case 3

The following is defined in the /etc/hosts file:
192.168.10.10    jupiter jupiter.ibm.com mars.ibm.com

pdadmin sec_master> server task default-webseald-nutshell create -t tcp -h mars.ibm.com /hostaliastest


Result:

The junction xml for the /hostaliastest junction shows the FQDN as it was given in the junction creation command.

Excerpt of the junction XML:
...
    <HOST>mars.ibm.com</HOST>
    <PORT>80</PORT>
    <VIRTHOSTNM>mars.ibm.com</VIRTHOSTNM>
...



Test case 4

The following is defined in the /etc/hosts file:
192.168.10.10    jupiter.ibm.com jupiter mars.ibm.com

pdadmin sec_master> server task default-webseald-nutshell create -t tcp -h mars.ibm.com /hostaliastest


Result:

Again like in the test case 3 the junction xml for the /hostaliastest junction shows the FQDN as it was given in the junction creation command.

Excerpt of the junction XML:
...
    <HOST>mars.ibm.com</HOST>
    <PORT>80</PORT>
    <VIRTHOSTNM>mars.ibm.com</VIRTHOSTNM>
...