lua-resty-rack

[James Hurst]

Hi all,

I've been working on some small applications using ngx_lua, and couldn't quite decide on a convention for loading / configuring modules. It occurred to me today that perhaps some kind of "Rack" like system - a simple predictable interface for creating middleware - would be useful?

So I created a module which looks a bit like Connect (http://www.senchalabs.org/connect/) for Node.js. The code is here as a "resty" module:

https://github.com/pintsized/lua-resty-rack

The idea is that you create a module by implementing a function called "call" which can accept parameters as a table, and in turn returns the function to be run when this middleware has its turn. Such as:

module("mymodule", package.seeall)

function call(options)

  return function(req, res, next)

    ... do things

    next() -- I'm done modifying the req/res, try the next middleware.

    -- or

    return ngx.HTTP_OK, headers, "Hello World" -- I'm taking over this request..

  end

end

You either return status, header, body, or just call next() if your job is more like a filter.

Here's an example small piece of middleware: https://github.com/pintsized/lua-resty-rack/blob/master/lib/resty/rack/method_override.lua

To use the middleware, you'd do something like:

server {

    location /test {

        content_by_lua '

            local rack = require "resty.rack"

            rack.use(rack.middleware.method_override)

            ... other middleware.. 

            rack.run()

        ';

    }

}

I just wrote this today, as an experiment.. any thoughts / ideas / alternative approaches would be appreciated :)

Cheers,

--

James Hurst

ja...@riverratrecords.com 

+44 (0) 7979 817 702 | @pintsized

River Rat Records

Politi Arts, 10 Manor Road, London, N16 5SA

www.riverratrecords.com | @riverratrecords

[agentzh]

Hello!

On Fri, Jun 1, 2012 at 12:47 AM, James Hurst <ja...@riverratrecords.com> wrote:
> I've been working on some small applications using ngx_lua, and couldn't
> quite decide on a convention for loading / configuring modules. It occurred
> to me today that perhaps some kind of "Rack" like system - a simple
> predictable interface for creating middleware - would be useful?
>

Your example looks interesting :) Thanks for sharing!

Regards,
-agentzh

[James Hurst]

Hi again,

I've worked on this a little more, and written some documentation. Hopefully some people will find it useful.. I'll try to write some better bundled utility middleware soon:

 https://github.com/pintsized/lua-resty-rack

Also, I've documented my HTTP caching middleware called "ledge", which is built using "lua-resty-rack":

 https://github.com/pintsized/ledge

The plan for this is much broader; serving stale requests, collapse forwarding, ESI, stats gathering, and I'm working on some "auto priming" tools for it to. For now, it simply does caching.

Any feedback welcome!

Cheers,

James.

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[agentzh]

Hello!

On Fri, Jun 8, 2012 at 10:45 PM, James Hurst <ja...@riverratrecords.com> wrote:
> Also, I've documented my HTTP caching middleware called "ledge", which is
> built using "lua-resty-rack":
>
>  https://github.com/pintsized/ledge
>
> The plan for this is much broader; serving stale requests, collapse
> forwarding, ESI, stats gathering, and I'm working on some "auto priming"
> tools for it to. For now, it simply does caching.
>

Awesome! I'm so glad to see that things are getting more and more
interesting here. It kinda reminds me of the ngx_srcache module:

https://github.com/agentzh/srcache-nginx-module

but it can surely do much more ;)

Thanks!
-agentzh