Varnish Cache and its usage in the real world!

Varnish Cache
and its usage in the real world
Ivan Chepurnyi
Owner
EcomDev BV

Ivan Chepurnyi
About me
Meet Magento
• 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

Ivan Chepurnyi Meet Magento
Varnish
is not a cache backend

Varnish
is a frontend caching proxy

Ivan Chepurnyi
Simple Workflow
Meet Magento
First call to a page

Ivan Chepurnyi
Simple Workflow
Meet Magento
Subsequent requests

Ivan Chepurnyi
How Varnish Works
Meet Magento
recv
hit passmiss
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

Ivan Chepurnyi
What can we do with it?
Meet Magento
• 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

Is it possible to clear Varnish
cache based on product, category,
store, etc?
YES!!!

The Secret is in
Cache Object structure

Ivan Chepurnyi
Cached Object in Varnish
Meet Magento
Cached Object
Response Headers
Response Body
Cache Metadata
Cache Content

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.

But is it possible to make cache lifetime
dynamic per product, category, etc?
YES!!!

You can supply a response header,
that contains a TTL of the page.

So what should be done to implement
Varnish in Magento with all the
benefits?

Ivan Chepurnyi
Varnish in Magento
Meet 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

But I have good news:
I alredy developed a module that gives you
a solid foundation for using Varnish in your
project!

Ivan Chepurnyi
EcomDev_Varnish
Meet Magento
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

Ivan Chepurnyi
Before you start using it…
Meet Magento
• 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

Making an element dynamic on varnish
cached page

Ivan Chepurnyi
Code Sample Dynamic Block
Meet Magento
<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

Ivan Chepurnyi
Available Dynamic Cookies
Meet Magento
• 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

Ivan Chepurnyi
How does it work?
Meet Magento
• 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

Adding custom TTL for a page

Ivan Chepurnyi
Code Sample Custom TTL
Meet Magento
// 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

Making custom page cacheable

Ivan Chepurnyi
Code Sample Custom Page
Meet Magento
<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_h
andle_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

Ivan Chepurnyi
Varnish vs Full Page Cache
Meet Magento
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

But why do I need to use
EcomDev_Varnish?

Ivan Chepurnyi
EcomDev_Varnish vs the others
Meet Magento
• 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

The choice is up to you!

Ivan Chepurnyi
OpenSource Roadmap 2014
Meet Magento
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)

Thank You!

Questions?
Email: ivan@ecomdev.org
Website: http://www.ecomdev.org
LinkedIn: http://nl.linkedin.com/in/ivanchepurnyi
Twitter: https://twitter.com/IvanChepurnyi

Varnish Cache and its usage in the real world!

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