if( hostname == "foo )
{
    print hostname;
    found = 1;
}

if( hostname == "foo )
{
    print hostname;
    found=1;
    exit( 0 );              # exit good; use non-zero to exit bad
}

 awk -v remove=XMPP_ec2-184-2-2-2 '
        /define host/ {                 # start of new block; print last section
                if( snarfed )
                        print snarfed;

                snarfed = $0;           # start capture
                next;
        }

        /host_name/ {                   # check to see if unwanted target
                if( $2 == remove )      # if it is then
                        snarfed = "";   # unset to trash the whole block
                next;
        }
        snarfed {                       # if we are snarfing from current section
                snarfed = snarfed "\n" $0;      # add next line
                next;
        }
        END {                           # must do one last for the last buffered section
                if( snarfed )
                        print snarfed;
        }
' config-file >new-file
mv config-file config-file.bak
mv new-file config-file