A file which is required or used must end with a true value. Just make

1;
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the last line of the config file.

It doesn't seem well-known, but return will stop execution of a loaded file, making return 0; a way to cancel loading and return 1; a way to say "You don't need the rest of this."

(Added) To keep strict happy, you should add,

use vars qw/$v1 ..... $variable $flag/;
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to the top of the file. Tacking on my won't work, since lexical variables only have file scope, at most, and can't be seen from the require-ing program.