Warning: This will likely take a bit of tweaking to get plugged into your system, but it is totally worth it when you do.

For a less-technical explanation, head over to http://aaronfrancis.com/blog/2013/6/19/yii-and-the-asset-pipeline-part-2.

The Mantis Asset Manager is a system for the PHP framework Yii that minifies, combines, and publishes files. This is not a drop-in replacement for the standard CAssetManager, but rather a new system for managing your assets. This was made specifically for getmantis.com, which is hosted on Heroku. The problem with hosting Yii on Heroku (or on Amazon EC2) is that there is no persistent filesystem. (You can read about my first attempt to solve this problem here.) Because there is no persistent filesystem, we can't rely on Yii's publishing mechanism because they could disappear at anytime. So this moves us to publishing our assets to Amazon S3, which is fine, because that's where they should be anyway. Uploading all your assets to S3 will likely take a long time, so we'd rather do that locally than rely on the webserver to do it. That way when we push our latest code live, all the assets are already published and ready to go.

The Mantis Manager does several things. On first run, it will loop through a directory of your choice (defaults to protected/assets/) and publish all your assets either locally or to your Amazon S3 bucket, depending on how how you run the command. In addition to publishing, it can minify and combine CSS and/or JS files prior to publishing.

When you run it the first time, Mantis will calculate the SHA1 of each file and store it away in the runtime folder. When you change a file, let's say edit a CSS file, you can run Mantis again and it will loop through and compare the SHAs and publish only the changed files. This ensures that your end users don't have to get new versions of your assets when nothing has changed, their browsers can rely on cached versions. For the assets that have changed, they will be at a new URL which will bust the cache immediately, especially helpful if you're using a CDN like Cloudfront.

You'll need more configuration for your console than you will for your web app, because you'll be doing all the publishing from the console. Here is my console configuration:

'mantisManager'=>array(
	'class'=>'MantisManager',
	'runtimePath'=>'application.runtime',
	'assetsPath'=>'application.assets',
	'localManager'=>'localAssets',
	'remoteManager'=>'remoteAssets',
	'ignore'=>array(
		'*.psd'
	),
	'css'=>array(
		'combine'=>array(
			'css/combined.css' => array(
				'css/base.css',
				'css/blue.css',
				'css/calendar.css',
				'js/bootstrap-select/bootstrap-select.css',
				'js/bootstrap-datepicker/datepicker.css',
				'css/styles.css',
			)
		),
		'minify'=>true
	),
	'js'=>array(
		'combine'=>array(
			'js/combined.js' => array(
				'js/bootstrap.js',
				'js/bootstrap-select/bootstrap-select.js',
				'js/bootstrap-datepicker/bootstrap-datepicker.js',
				'js/mantis.js'
			)
		),
		'minify'=>true
	)
),

You can see here that I've set up the manager to ignore any .psd files, minify all CSS, combine a few css files and put them into a css/combined.css file, minify all JS, combine a few JS into js/combined.js. You can check the /config/env/local/console.php file for all the relevant info. Remember, this is just the config for the console application.

For the web app, your configuration is much less, because you're just reading information, not doing any publishing.

'mantisManager'=>array(
	'class'=>'MantisManager',
	'type'=>'local'
),

We just set up the class and tell the manager what mode we're in (local or remote).

Once you have everything set up, you invoke Mantis from the command line using $ ./yiic mantis. This will kick off the the publishing loop. Your console will keep you up to date with what's happening. When you're ready to publish to S3, you can run $ ./yiic mantis --type=remote, which will use your remoteManager from your config to publish.

If you have to, you can kill all the cache files by running $ ./yiic mantis reset. Note: this doesn't delete your files, it just kills the cache that holds the reference to the files. You'll have to delete the files yourself.

If you are working locally, you can run the $ ./yiic mantis watch command to continuously publish your files. It suppresses all console messages except warnings and notifications of updated files. Useful for when files are changing rapidly.

Since the asset URLs are always changing, we need a way to reference them consistently. We're going to hook into the Controller to do this. I've created a Controller class that all my controllers inherit from. Then I can use my assests by calling $this->asset(). For example, in a view we just call <img src="<?php $this->asset("/original/path/to/asset.png") ?>" /> and it'll turn into something like <img src="/1/s2sd345/asset.png" />, which is the most current version of our asset.png.

You'll likely need access to your assets in your CSS code too. Mantis will process all your CSS files and look for references in the format of {{asset("/original/path/to/asset.png")}}. Mantis will then replace that template with "/1/s2sd345/asset.png".

The S3 Asset Manager used here is a heavily modified version of the Yii-S3AssetManager, which makes use of the ES3 extension, which I leave unmodified.

To minify the CSS, I've used an unmodified version of minify.

To minify the JS, I've used an unmodified version of JShrink.