load balancing and if statements

[Brian De Wolf]

On Mon, 26 Mar 2012 11:46:22 -0700
Scott McLane Gardner <sgardne at uark.edu> wrote:

> If I can't use if statements in a load balance block, can anyone
> suggest another way to go about accomplishing what I want to do here?

After reading this thread and realizing it affects my implementation
(though with mysql), I started poking at this to work out a solution.

The real problem with trying to build this in unlang is that there
doesn't seem to be a way to differentiate between a failed Sql-Group
check and a negative result.  Instead, I have to cheese it out with
an XLAT no-op to see if the SQL server is responding.  If I'm missing
something useful here, please let me know.  I'd love some feedback from
the gurus.  Anyway, the config bits:

policy {
# ...
        mysql-1-disabled {
		if("%{mysql-1:SELECT 'test'}" != "test") {
			fail
                }
                if(mysql-1-Sql-Group == "disabled") {
                        reject
                }
                else { 
                        ok
                }
        }
        mysql-2-disabled {
                if("%{mysql-2:SELECT 'test'}" != "test") {
                        fail
                }
                if(mysql-2-Sql-Group == "disabled") {
                        reject
                }
                else { 
                        ok
                }
        }
}

instantiate {
# ...
        redundant-load-balance sql-disabled {
                mysql-1-disabled
                mysql-2-disabled
        }
}


Once this is in, "sql-disabled" can be placed in an authorize{} block.


I really wish there was a better way to do this...