On Sat, Mar 10, 2007 at 01:18:50PM -0500, Jonathan Vanasco wrote:

It's not possible for reasons descreibed below.

What it should "return" at http level ?

http { return 404; }

?

nginx has three type of configuration directives:

1) static: the most directives, 2) partially dynamic: the directives with $variable paramters, 3) and dynamic: if/rewrite/set/break/return.

The static directives are compiled into binary structures for each server and locations and they are usually availabe via three and so memory accesses.

The partially dynamic directives are also compiled into binary structures and besides the dynamic parts are compiled into some code that run at request processing stage.

The dynamic directives are compiled into some code that run at request processing stage. They can not be used to choose configuration parts.

Initially the rewrite module was developed under the influence of Apache's mod_rewrite (the "rewrite" direcive). Then the "if" block appeared and this block configuration is considred as some static location configuration: if you use

if (some_true_value) { configuration A }

if (some_true_value_too) { configuration B }

you get configuration B, but not A+B. To use configuration A, you should use the "break" inside first block.

I do not like the current state of rewrite module, but still did not decide how to change it internally to allow dynamic configurations. There is currently the only workaround:

# static if (...) { limit_rate 1k; }

# fully dynamic: if (...) { set $limit_rate 1k; }