Varnish Cache and its usage in the real world!
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Transcript of Varnish Cache and its usage in the real world!
Varnish Cache and its usage in the real world
Ivan ChepurnyiOwner
EcomDev BV
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About me
• Technical Consultant, Owner at EcomDev B.V.
• Started as one of the first five developers in original Magento core team
• Magento Developer Coach in Europe
• Main areas of my expertise:– System Architecture – Performance Optimization– Test Driven Development– Complex Customizations
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Varnish
is not a cache backend
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Varnish
is a frontend caching proxy
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Simple Workflow
First call to a page
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Simple Workflow
Subsequent requests
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How Varnish Works
recv
hit pass miss
hash pipe
deliver
fetch
• recv – request is received from client
• pipe – direct output of backend data (streaming)
• hash – request is cacheable, lookup cache entry
• pass – request is not cacheable
• hit – cache entry is found
• miss – cache entry not found
• fetch – retrieval of data from backend
• deliver – return data to client
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What can we do with it?
• Cache static pages (Homepage, CMS, Contacts, etc)
• Cache catalog pages:– Category listings– Product search results– Product view pages
• Cache page parts:– CMS Blocks– Header– Footer
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Is it possible to clear Varnish cache based on product, category,
store, etc?
YES!!!
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The Secret is in
Cache Object structure
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Cached Object in Varnish
Cached Object
Response Headers
Response Body
Cache Metadata
Cache Content
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We just going to supply object ID with its type in response headers, so it later
on can be used to flush pages containing our object.
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But is it possible to make cache lifetime dynamic per product, category, etc?
YES!!!
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You can supply a response header, that contains a TTL of the page.
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So what should be done to implement Varnish in Magento with all the
benefits?
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Varnish in Magento
• Collect current page objects, that are shown on the page. Also add them into response headers.
• Create a connector to a Varnish admin protocol, that will be used for flushing of the page by object ids.
• Implement auto-updated AJAX blocks for:– Shopping cart– Wishlist– Customer Account links
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But I have good news:
I alredy developed a module that gives you a solid foundation for using Varnish in your
project!
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EcomDev_Varnish
Download URL: http://bit.ly/ecomdev_varnish
Requires:• Varnish 3.0• Minimal changes to your theme
Supports:• Flush of cache on update of product, category, cms page, csm
block, price rules• Client side cacheable AJAX placeholders (Cart, Wishlist, etc)• Possibility to make a cache based on customer segment • Cache for logged in users
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Before you start using it…
• Make a list of dynamic blocks in your project:– Shopping Cart– Login blocks– Special Promo for Customer
• Validate possible visitor segments of your project:– Customer group– Language / Country
• Make a list of themes you need to modify
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Making an element dynamic on varnish cached page
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Code Sample Dynamic Block
<default_varnish>
<reference name=”parentBlock”>
<action method="unsetChild”>
<block>dynamicBlockAlias</block>
</action>
<block
as="dynamicBlockAlias”
name=”dynamicBlockPlaceholder"
template="ecomdev/varnish/wrapper/placeholder.phtml"
type="core/template">
<action method="append">
<block>dynamicBlock</block>
</action>
<action method="setBlockName">
<block>dynamicBlock</block>
</action>
<action method="setCookie">
<cookie>dynamicCookie</cookie>
</action>
<action method="setWrapperId">
<htmlId>elementId</htmlId>
</action>
</block>
</reference>
</default_varnish>
Layout File • parentBlock – name of the parent block
• dynamicBlockAlias – alias of the dynamic block in parent block
• dynamicBlockPlaceholder – unique name of your placeholder
• dynamicBlock – name of the original dynamic block
• dynamicCookie – name of the cookie for dynamic blocks
• elementId – HTML ID for the placeholder div, that is going to be used as container
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Available Dynamic Cookies
• quote_checksum – checksum of the current quote contents
• customer_checksum – checksum based on the customer identification, if logged in customer gets changed
• is_logged_in – boolean flag of the logged in state of the visitor
• segment_checksum – checksum of the current customer segment: – customer group id– store view
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How does it work?
• Your original block gets wrapped by a custom div with some JS code
• When customer visits a page, JS checks for a cookie value and compares it with latest saved one in local/session storage
• If it is different it requests /varnish/ajax/reload for retrieving dynamic content and saves it to local/session storage
• If it is the same, it just updates block from local/session storage
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Adding custom TTL for a page
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Code Sample Custom TTL
// Somewhere in your code you just simply call it
// Varnish module will take the lowest value in array of TTL that were added
Mage::helper(‘ecomdev_varnish’)
->addTtl($timeInSeconds);
Code Block
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Making custom page cacheable
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Code Sample Custom Page
<config> <varnish> <pages> <layout_handle_name translate="label" module=”your_module"> <label>Your Page Name</label> </layout_handle_name> </pages> </varnish>
<default> <varnish> <pages>
<layout_handle_name_time>360</layout_handle_name_time>
</pages> </varnish> </default></config>
config.xml• layout_handle_name – full
name of the layout handle that should be cacheable
• your_module – name of the module used for translation of label
• Your Page Name – name of your pages, that will be shown in System Configuration - Varnish Cache
• 360 – default cache lifetime of the page
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Varnish vs Full Page Cache
Varnish
• Avg. time to first byte 30ms
• Dedicated software
• Tools to monitor cache usage
• Scalable
• Requires adaptation of themes for dynamic parts
• Possibility to flush group of pages
Magento FPC implementation
• Avg. time to first byte 300-400ms
• Magento code level
• N/A
• Only as another backend node
• Most of the time it is not required
• N/A
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But why do I need to use EcomDev_Varnish?
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EcomDev_Varnish vs the others
• Cache lifetime specified on Magento code level, without changing VCL
• By using collectors & processors, it can be easily extended to support additional entities
• Client-side cacheable dynamic parts
• Cache enabled for all kind of visitors
• Saves your money on hardware
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The choice is up to you!
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OpenSource Roadmap 2014
1. Finalize EcomDev_Varnish module and make it open source;
2. EcomDev_PHPUnit refactoring for API based fixtures;Progress: 20%
3. Working on EcomDev_Index module, to provide alternative of standard indexation mechanism in Magento:– Flat Indexers (failover indexation)– UrlRewrites (full refactor of existing module)– Layered Navigation (Sphinx)– Better Search (Sphinx)
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Thank You!
Questions?
Email: [email protected]
Website: http://www.ecomdev.org
LinkedIn: http://nl.linkedin.com/in/ivanchepurnyi
Twitter: https://twitter.com/IvanChepurnyi