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https://github.com/jthomerson/libvmod-timeutils

VMOD for Varnish Cache which adds time utilities.
https://github.com/jthomerson/libvmod-timeutils

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VMOD for Varnish Cache which adds time utilities.

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README 

        
==============

vmod_timeutils

==============



-------------------------

Varnish Time Utils Module

-------------------------



:Manual section: 3

:Author: Jeremy Thomerson

:Date: 2012-10-17

:Version: 0.1



SYNOPSIS

========



::



	import timeutils;



	timeutils.rfc_format();

	timeutils.expires_from_cache_control();

	timeutils.version()



DESCRIPTION

===========



Varnish Module (vmod) that assists with date-related functions in VCL,

including manipulation of date-formatted headers.  For instance, if you

always want to add a specific amount of time to an Expires header, this

module provides an easy way to do so.



FUNCTIONS

=========



Example VCL::



	backend some_backend { ... };



	import timeutils;



	sub vcl_deliver {

		// always set the expires header ten minutes from now

		set resp.http.Expires = timeutils.rfc_format(now + 10m);

		// set the Expires header from the max-age value returned in the

		// Cache-Control response header if it is there, otherwise 15m from now

		set resp.http.Expires = timeutils.expires_from_cache_control(15m);

		// only useful for debugging, returns the version of timeutils:

		set resp.http.X-TimeUtils-Version = timeutils.version();

	}



expires_from_cache_control

--------------------------



Prototype

	timeutils.expires_from_cache_control()

Returns

	string

Description

	Tries to obtain the max-age value from the `resp` Cache-Control header

	and use it to calculate a new Expires date.  If the Cache-Control header

	does not exist or the max-age value can not be determined, this will use

	your default duration and add it to the current time, returning a formatted

	date of now + `default_duration`.

Example

	``set resp.http.Expires = timeutils.expires_from_cache_control(30m);``



rfc_format

----------



Prototype

	timeutils.rfc_format()

Returns

	string

Description

	Formats a date represented by `duration` into an RFC compliant format.

	Using default VCL ``set resp.http.Expires = now + 10m`` would result in

	a double value - the number of seconds since the epoch.  Using

	rfc_format will allow you to do those date calculations and return a

	properly formatted date.

Example

	``set resp.http.Expires = timeutils.rfc_format(now + 30m);``



version

-------



Prototype

	timeutils.version()

Returns

	string

Description

	Returns the string constant version-number of the timeutils vmod.

	Primarily useful only for debugging.

Example

	``set resp.http.X-TimeUtils-Version = timeutils.version();``



INSTALLATION

============



Installation requires the Varnish source tree (only the source matching the

binary installation).



1. `./autogen.sh`  (for git-installation)

2. `./configure VARNISHSRC=/path/to/your/varnish/source/varnish-cache`

3. `make`

4. `make install` (may require root: sudo make install)

5. `make check` (Optional for regression tests)



VARNISHSRCDIR is the directory of the Varnish source tree for which to

compile your vmod. Both the VARNISHSRCDIR and VARNISHSRCDIR/include

will be added to the include search paths for your module.



Optionally you can also set the vmod install dir by adding VMODDIR=DIR

(defaults to the pkg-config discovered directory from your Varnish

installation).



ACKNOWLEDGEMENTS

================



This plugin was heavily influenced by two modules developed by the Varnish team:

vmod_header and vmod_example.



Author: Jeremy Thomerson , Expert Tech Services, LLC



HISTORY

=======



Version 0.1: Initial version, with two simple but useful functions.  My first vmod ever.



BUGS

====



I'm sure there will be some.  Leaving this as a placeholder to document them.



SEE ALSO

========



* varnishd(1)

* vcl(7)

* https://github.com/jthomerson/libvmod-timeutils



COPYRIGHT

=========



This document is licensed under the same license as the

libvmod-timeutils project. See LICENSE for details.



* Copyright (c) 2012 Jeremy Thomerson, Expert Tech Services, LLC