In this talk, Jeff Valeo from Grubhub will talk about how they leveraged Fastly to slowly migrate user traffic from a legacy monolith to a new, service-based architecture. This solution allowed Grubhub to shift millions of users as new functionality was built with zero downtime.

1. Moving Off The Monolith:
A Seamless Migration

2. About Grubhub
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! Grubhub is the nation's leading online and mobile takeout
food-ordering marketplace
! Grubhub, Seamless, AllMenus and MenuPages
! 15.6 million active diners
! More than 420,000 average daily orders
! $1.2 billion gross food sales Q2 2018

3. A Brief History Lesson
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! May 2013 Grubhub and Seamless merger
! 2 totally independent monoliths (on monoliths)
! .NET & Java
! Self-hosted, single data centers
! Doomsday approaching

4. Phase 1: Consolidation
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! Consolidated most (will come back to this) users onto the
Grubhub monolith
! One time, ongoing and on-demand diner and data sync
! No traffic cutover yet

5. Phase 2: To The Cloud
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! Extremely complicated system to move
○ Hyperlocal e-commerce platform
○ Order fulfillment pipeline
○ Restaurant facing technology
○ Accounting
○ Delivery ecosystem
○ Much more
! Building a bridge was key

6. Phase 2: To The Cloud Via a Bridge In France
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7. Phase 2: The Bridge
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! Responsible for bidirectional sync of data
! Only new service with context of legacy monolith (but not
access)
! Direct legacy DB access
! Future proof contracts to an extent
! Built on new frameworks

8. Phase 3: Shifting Traffic
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! Grubhub was easy
○ Migrate diners
○ Migrate data
○ Release www
○ Release mobile
○ fin
! Seamless only in name...

9. Phase 4: Seamless
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! Seamless has a large corporate customer base
! Allows large companies to sign up with consolidated billing,
lines of credit, catering, et cetera
! Plan to cut over www.seamless.com to the new platform for
diners but leaving corporate on existing stack

10. Logic At The Edge
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! Some way to identify intent
! Stick users to an experience
! Use that logic to route to correct backend

11. Logic At The Edge
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12. Additional Bits
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! Logic to help ongoing migration efforts
! Account for SEO traffic
! Monitoring origin rates to ensure logic is sound

13. Time Passes...
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14. Current State
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! Logic still in place to direct to correct stack
! Moved almost everything out of the Grubhub monolith
! Still using the bridge where needed
! Wins in logic at the edge convinced us to add additional
functionality

15. (More) Logic At The Edge
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! GEO based blocking/logic
○ Allows easy/programmatic whitelisting
! Per POP routing
○ We keep a map of POP → Origin DC in edge dictionary
○ Can shift single POP to alternate origin for traffic balancing
! Rolling fail-out
○ Using per POP routing and knowledge of busiest POPs
safely fail-out an origin DC
! More to come
○ % load shedding
○ Fail-out particular route/services

16. (More) Logic At The Edge
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17. (More) Logic At The Edge
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18. Recap
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! Building a bridge
! Embracing logic at the edge
! Building custom interaction and display layers where needed
! PS - We’re hiring! jvaleo@grubhub.com

19. Thank you!
jvaleo@grubhub.com