Disable Full Page Cache Only For CMS Pages

Question

For some reason I want to disable Full Page Cache for CMS pages including Home Page.
I have created my custom module for this but some reason it is not working.
config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Custom_HeaderFix>
            <version>1.0.0</version>
        </Custom_HeaderFix>
    </modules>
    <global>
        <models>
            <headerFix>
                <class>Custom_HeaderFix_Model</class>
            </headerFix>
        </models>
    </global>
    <frontend>
        <events>
            <controller_action_predispatch_cms>
                <observers>
                    <headerCache>
                        <type>singleton</type>
                        <class>headerFix/observer</class>
                        <method>processPreDispatch</method>
                    </headerCache>
                </observers>
            </controller_action_predispatch_cms>
        </events>
    </frontend>
</config>

Observer.php

<?php

class Custom_HeaderFix_Model_Observer {

    public function processPreDispatch(Varien_Event_Observer $observer) {
        $action = $observer->getEvent()->getControllerAction();

        if ($action instanceof Mage_Cms_PageController) {
        $cache = Mage::app()->getCacheInstance();

        // Tell Magento to 'ban' the use of FPC for this request
        $cache->banUse('full_page');
        }
    }

}

My code is working on CMS pages but not for home page

Answer 1

If it works for all pages, except the home page, you should replace

if ($action instanceof Mage_Cms_PageController)

with

if ($action instanceof Mage_Cms_PageController
    || $action instanceof Mage_Cms_IndexController) 

Answer 2

The full page cache uses the event controller_action_predispatch as well and its observer will be executed first because core modules are always loaded before local modules.

I see two possible solutions:

1. use an event that is triggered before, like controller_front_init_routers - the problem here is that the controller action is not determined yet so you'll have to use the routers' matching methods. This probably makes the page load remarkably slower

2. Rewrite the full page cache observer pagecache/observer and override processPreDispatch() to check for the controller action before calling the parent method.