Hi, Maybe many times asked by others, but we have an application which has to return the hostname. But in our MC-Serviceguard it will give the hostname of the active node, instead of returning the packagename. We cannot modify the application and do not want to give both nodes the same hostname. Is there a way of fooling the application?
Regards, Ceesjan ps. I do not know what the application uses internally 'hostname; uname...'.
How is your application pulling the name? By system call like uname(), gethostname(), gethostbyname() etc.? Or is it parsing the output from an external command?
Consider how ServiceGuard works. Nodes in a cluster can run more than one package at once, therefore can pretend to be more than one host at once. The package name/IP becomes a kind of virtual server that can run on many nodes. The packages are listed in cmviewcl. How you gain access to the package is often via the IP address that is given to the package, which sits in the hosts files and in DNS for the clients, so that the clients don't have to know which node the package is running on. If you cannot modify the application and do not know how it works then there really isn't much you can do to the app. Ensuring that your application works in a package and isn't locked to a hostname is a key feature of serviceguard and should be in everyone's test plan. I have seen projects get stuck on this issue with respect to software licencing checks.
To my knowledge there is no way to fool the application without adverse consequences to other parts of the system. For instance, changing the hostname to the package IP alias will break SG commands.
The section labeled "Designing Applications to Run on Multiple Systems" in the "Managing Serviceguard" manual describes the correct approach:
Uhmm, I sorta hate to offer this as a suggestion, and you might break something doing it, but you could try creating some small scripts from 'hostname' and 'uname' and putting them in a directory at the start of your PATH variable that would just echo out the hostname you want. Sorta a bad hack, but might resolve the problem.
Otherwise, contacting your application vendor to see how to do it would be the next best thing.
Greetings to you all. We've found a way to set a fixed 'ServerName' into the applicationconfig. Setting this var on the packagename was the only way to solve it. We didn't see the clue on page 229 of the our appl.manual in very small letters.
