NAME

Catalyst::Controller::AutoAssets - Automatic asset serving via sha1-based URLs

VERSION

version 0.10

SYNOPSIS

In your controller:

  package MyApp::Controller::Assets::MyCSS;
  use parent 'Catalyst::Controller::AutoAssets';
  
  1;

Then, in your .conf:

  <Controller::Assets::MyCSS>
    include   root/my_stylesheets/
    type      css
    minify    1
  </Controller::Assets::MyCSS>

And in your .tt files:

  <head>
    <link rel="stylesheet" type="text/css" href="[% c.controller('Assets::MyCSS').asset_path %]" />
  </head>

Or, in static HTML:

  <head>
    <link rel="stylesheet" type="text/css" href="/assets/mycss/current.css" />
  </head>
  

DESCRIPTION

Fast, convenient serving of assets (css, javascript, etc) at URL path(s) containing a sha1 checksum of the content. This is an alternative/supplement to Catalyst::Plugin::Static::Simple or external/webserver for serving of an application's "nearly static" content.

The benefit of serving files through CAS paths ("content-addressable storage" - same design used by Git) is that it automatically alleviates client caching issues while still allowing for maximum aggressive cache settings. Because URL paths contain the sha1 checksum of the data, browsers can safely cache the content forever because "changes" automatically become new URLs. If the content (CSS, JavaScript or other) is modified later on, the client browsers instantly see the new version.

This is particularly useful when deploying new versions of an application where client browsers out in the network might have cached CSS and JavaScript from previous versions. Instead of asking users to hit "F5", everyone gets the new content automagically, with no intervention required. All you have to do is change the content; the module handles the rest.

This module also provides some optional extra features that are useful in both development and production environments for automatically managing, minifying and deploying CSS and JavaScript assets.

CONFIG PARAMS

type

Required - The asset type: directory, css or js.

The directory asset type works in a similar manner as Static::Simple to make some directory structure accessible at a public URL. The root of the structure is made available at the URL path:

  <CONTROLLER_PATH>/<SHA1>/

MIME::Types is used to set the Content-Type HTTP header based on the file extension (same as Static::Simple does).

Because the sha1 checksum changes automatically and is unknown in advance, the above Asset Path is made available via the asset_path() controller method for use in TT files and throughout the application.

The css and js types serve one automatically generated text file that is concatenated and optionally minified from the include files. The single, generated file is made available at the URL Path:

  <CONTROLLER_PATH>/<SHA1>.js    # for 'js' type
  <CONTROLLER_PATH>/<SHA1>.css   # for 'css' type

The js/css types provide a bonus mode of operation to provide a simple and convenient way to manage groups of CSS and JavaScript files to be automatically deployed in the application. This is also particularly useful during development. Production applications with their own management and build process for CSS and JavaScript would simply use the directory type.

include

Required - String or ArrayRef. The path(s) on the local filesystem containing the source asset files. For directory type this must be exactly one directory, while for css and js it can be a list of directories. The include directory becomes the root of the files hosted as-is for the directory type, while for css and js asset types it is the include files concatinated together (and possibly minified) to be served as the single file.

current_redirect

Whether or not to make the current asset available via 307 redirect to the real, current checksum/fingerprint asset path. This is a pure HTTP mechanism of resolving the asset path.

  <CONTROLLER_PATH>/current/      # for 'directory' type
  <CONTROLLER_PATH>/current.js    # for 'js' type
  <CONTROLLER_PATH>/current.css   # for 'css' type

For instance, you might reference a CSS file from a directory asset Controller::Assets::ExtJS using this URL path (i.e. href in an HTML link tag):

  /assets/extjs/current/resources/css/ext-all.css

This path would redirect (HTTP 307) to the current asset/file path which would be something like:

  /assets/extjs/1512834162611db1fab246dfa87e3a37f68ed95f/resources/css/ext-all.css

The downside of this is that the server has to serve the non-cachable redirect every time, which partially defeats the performance benefits of this module (although the redirect is comparatively lightweight).

The other mechanism to find the current asset path is via the asset_path() method, which returns the current path outright and is the recommended usage, but is only available in locations where application controller methods can be called (like in TT files).

Defaults to true (1).

current_alias

Alias to use for the current_redirect. Defaults to 'current' (which also implies 'current.js'/'current.css' for js and css asset types).

minify

Whether or not to attempt to minify content for css or js asset types. This is a purely optional convenience feature.

Defaults to false (0). Does not apply to the directory asset type.

minifier

CodeRef used to minify the content when minify is true. The default code is a pass-through to CSS::Minifier::minify() for css assets and JavaScript::Minifier::minify() for js. If you want to override you must follow the same API as in those modules, using the input and outfile filehandle interface. See JavaScript::Minifier and CSS::Minifier for more details.

Does not apply to the directory asset type.

work_dir

The directory where asset-specific files are generated and stored. This contains the checksum/fingerprint file, the lock file, and the built file. In the case of directory assets the built file contains a manifest of files and in the case of css and js assets it contains the actual asset content (concatenated and possibly minified)

Defaults to:

  <APP_TMPDIR>/AutoAssets/<CONTROLLER_PATH>/

max_lock_wait

Number of seconds to wait to obtain an exclusive lock when recalculating/regenerating. For thread-safety, when the system needs to regenerate the asset (fingerprint and built file) it obtains an exclusive lock on the lockfile in the work_dir. If another thread/process already has a lock, the system will wait for up to max_lock_wait seconds before giving up and throwing an exception.

Note that this is only relevant when the source/include content changes while the app is running (which should never happen in a production environment).

Defaults to 120 seconds.

max_fingerprint_calc_age

Max number of seconds before recalculating the fingerprint of the content (sha1 checksum) regardless of whether or not the mtime has changed. 0 means infinite/disabled.

For performance, once the system has calculated the checksum of the asset content it caches the mtime of the include file(s) and verifies on each request to see if they have changed. If they have, it regenerates the asset on the fly (recalculates the checksum and concatenates and minifies (if enabled) for css and js asset types). If max_fingerprint_calc_age is set to a non-zero value, it will force the system to regenerate at least every N seconds regardless of the mtime. This would only be needed in cases where you are worried the content could change without changing the mtime which shouldn't be needed in most cases.

Defaults to 0.

asset_content_type

The content type returned in the 'Content-Type' header. Defaults to text/css or text/javascript for the css and js types respectively.

Does not apply to directory asset type. For files within directory type assets, the Content-Type is set according to the file extension using MIME::Types.

cache_control_header

The HTTP 'Cache-Control' header to return when serving assets. Defaults to the maximum aggressive value that should be honored by most browsers (1 year):

  public, max-age=31536000, s-max-age=31536000

METHODS

is_dir

Returns true (1) if the asset type is directory and false (0) if the type is css or js.

asset_path

Returns the current, public URL path to the asset:

  <CONTROLLER_PATH>/<SHA1>       # for 'directory' type
  <CONTROLLER_PATH>/<SHA1>.js    # for 'js' type
  <CONTROLLER_PATH>/<SHA1>.css   # for 'css' type

For directory asset types, accepts an optional subpath argument to a specific file. For example, if there was a file images/logo.gif within the include directory, $c->controller('Foo::MyAsset')->asset_path('images/logo.gif') might return:

  /foo/myasset/1512834162611d99fab246dfa87345a37f68ed95f/images/logo.gif

SEE ALSO

Catalyst::Plugin::Assets
Catalyst::Controller::VersionedURI
Plack::Middleware::Assets
Plack::Middleware::JSConcat

AUTHOR

Henry Van Styn <vanstyn@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by IntelliTree Solutions llc.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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