notes1

[Anders Berg]

I have been playing around with trying to structure/document the
Configuration Language:

http://klikk.vg.no/vcl.html

I just wanna ask if I am wasting my time before I continue?
Don't we need this in one form or another? Or have your rocket-speed
fingers already done this Poul?

Anders Berg



> -----------------------------------------------------------------------
Configuration Language
> XXX: include lines.
> BNF:
> 	program:	function
> 			| program function
> 	function:	"sub" function_name compound_statement
> 	compound_statement:	"{" statements "}"
> 	statements:	/* empty */
> 			| statement
> 			| statements statement
> 	statement:	if_statement
> 			| call_statement
> 			| "finish"
> 			| assignment_statement
> 			| action_statement
> 	if_statement:	"if" condition compound_statement elif_parts else_part
elif_parts:	/* empty */
> 			| elif_part
> 			| elif_parts elif_part
> 	elif_part:	"elseif" condition compound_statement
> 			| "elsif" condition compound_statement
> 			| "else if" condition compound_statement
> 	else_part:	/* empty */
> 			| "else" compound_statement
> 	call_statement:	"call" function_name
> 	assign_statement:	field "=" value
> 	field:		object
> 			field "." variable
> 	action_statement:	action arguments
> 	arguments:	/* empty */
> 			arguments | argument
> -----------------------------------------------------------------------
Sample request policy program
> 	sub request_policy {
> 		if (client.ip in 10.0.0.0/8) {
> 			no-cache
> 			finish
> 		}
> 		if (req.url.host ~ "cnn.no$") {
> 			rewrite	s/cnn.no$/vg.no/
> 		}
> 		if (req.url.path ~ "cgi-bin") {
> 			no-cache
> 		}
> 		if (req.useragent ~ "spider") {
> 			no-new-cache
> 		}
> 		if (backend.response_time > 0.8s) {
> 			set req.ttlfactor = 1.5
> 		} elseif (backend.response_time > 1.5s) {
> 			set req.ttlfactor = 2.0
> 		} elseif (backend.response_time > 2.5s) {
> 			set req.ttlfactor = 5.0
> 		}
> 		/*
> 		 * the program contains no references to
> 		 * maxage, s-maxage and expires, so the
> 		 * default handling (RFC2616) applies
> 		 */
> 	}
> -----------------------------------------------------------------------
Sample fetch policy program
> 	sub backends {
> 		set backend.vg.ip = {...}
> 		set backend.ads.ip = {...}
> 		set backend.chat.ip = {...}
> 		set backend.chat.timeout = 10s
> 		set backend.chat.bandwidth = 2000 MB/s
> 		set backend.other.ip = {...}
> 	}
> 	sub vg_backend {
> 		set backend.ip = {10.0.0.1-5}
> 		set backend.timeout = 4s
> 		set backend.bandwidth = 2000Mb/s
> 	}
> 	sub fetch_policy {
> 		if (req.url.host ~ "/vg.no$/") {
> 			set req.backend = vg
> 			call vg_backend
> 		} else {
> 			/* XXX: specify 404 page url ? */
> 			error 404
> 		}
> 		if (backend.response_time > 2.0s) {
> 			if (req.url.path ~ "/landbrugspriser/") {
> 				error 504
> 			}
> 		}
> 		fetch
> 		if (backend.down) {
> 			if (obj.exist) {
> 				set obj.ttl += 10m
> 				finish
> 			}
> 			switch_config ohhshit
> 		}
> 		if (obj.result == 404) {
> 			error 300 "http://www.vg.no"
> 		}
> 		if (obj.result != 200) {
> 			finish
> 		}
> 		if (obj.size > 256k) {
> 			no-cache
> 		} else if (obj.size > 32k && obj.ttl < 2m) {
> 			obj.tll = 5m
> 		}
> 		if (backend.response_time > 2.0s) {
> 			set ttl *= 2.0
> 		}
> 	}
> 	sub prefetch_policy {
> 		if (obj.usage < 10 && obj.ttl < 5m) {
> 			fetch
> 		}
> 	}
> -----------------------------------------------------------------------

> _______________________________________________
> varnish-dev mailing list
> varnish-dev at projects.linpro.no
> http://projects.linpro.no/mailman/listinfo/varnish-dev