This document discusses 8 cloud design patterns: External Configuration, Cache Aside, Federated Identity, Valet Key, Gatekeeper, Circuit Breaker, Retry, and Strangler. It provides an overview of each pattern, including what problem it addresses, when to use it, considerations, and examples of cloud offerings that implement each pattern. It aims to help developers understand and apply common best practices for cloud application design.
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8 cloud design patterns you ought to know - Update Conference 2018
1. 8 Cloud Design Patterns you
ought to know
Taswar Bhatti
System/Solutions Architect at Gemalto (Canada)
Microsoft MVP
2. Ponder
• For every 25 percent increase in problem complexity, there is a 100
percent increase in solution complexity.
• There is seldom one best design solution to a software problem.
• If cars were like software, they would crash twice a day for no reason,
and when you called for service, they’d tell you to reinstall the engine.
3. Who am I
• Taswar Bhatti – Microsoft MVP since 2014
• Global Solutions Architect/System Architect at Gemalto
• In Software Industry since 2000
• I know Kung Fu (Languages)
6. Agenda
• What are Patterns?
• The External Configuration Pattern
• The Cache Aside Pattern
• The Federated Identity Pattern
• The Valet Key Pattern
• The Gatekeeper Pattern
• The Circuit Breaker Pattern
• The Retry Pattern
• The Strangler Pattern
• Demo
• Questions
22. What are Patterns?
• General reusable solution to a recurring problem
• A template on how to solve a problem
• Best practices
• Patterns allow developers communicate with each other in well
known and understand names for software interactions.
24. External Configuration Pattern
• Helps move configuration information out of the application
deployment
• This pattern can provide for easier management and control of
configuration data
• For sharing configuration data across applications and other
application instances
28. Problems
• Configuration becomes part of deployment
• Multiple applications share the same configuration
• Hard to have access control over the configuration
30. When to use the pattern
• When you have shared configuration, multiple application
• You want to manage configuration centrally by DevOps
• Provide audit for each configuration
31. When not to use
• When you only have a single application there is no need to use this
pattern it will make things more complex
35. Cache Aside Pattern
• Load data on demand into a cache from datastore
• Helps improve performance
• Helps in maintain consistency between data held in the cache and
data in the underlying data store.
38. When to use the pattern
• Resource demand is unpredictable.
• This pattern enables applications to load data on demand
• It makes no assumptions about which data an application will require
in advance
39. When not to use
• Don’t use it for data that changes very often
40. Things to consider
• Sometimes data can be changed from outside process
• Have an expiry for the data in cache
• When update of data, invalidate the cache before updating the data
in database
• Pre populate the data if possible
43. Federated Identity Pattern
• Delegate authentication to an external identity provider.
• Simplify development, minimize the requirement for user
administration
• Improve the user experience of the application
• Centralized providing MFA for user authentication
46. Problem
• Complex development and maintenance (Duplicated code)
• MFA is not an easy thing
• User administration is a pain with access control
• Hard to keep system secure
• No single sign on (SSO) everyone needs to login again to different
systems
48. When to use
• When you have multiple applications and want to provide SSO for
applications
• Federated identity with multiple partners
• Federated identity in SAAS application
49. When not to use it
• You already have a single application and have custom code that
allows you to login
50. Things to consider
• The identity Server needs to be highly available
• Single point of failure, must have HA
• RBAC, identity server usually does not have authorization information
• Claims and scope within the security auth token
53. Valet Key Pattern
• Use a token that provides clients with restricted direct access to a
specific resource
• Provide offload data transfer from the application
• Minimize cost and maximize scalability and performance
57. When to use it
• The application has limited resources
• To minimize operational cost
• Many interaction with external resources (upload, download)
• When the data is stored in a remote data store or a different
datacenter
58. When not to use it
• When you need to transform the data before upload or download
61. Gatekeeper Pattern
• Using a dedicated host instance that acts as a broker between clients
and services
• Protect applications and services
• Validates and sanitizes requests, and passes requests and data
between them
• Provide an additional layer of security, and limit the attack surface of
the system
67. Things to consider
• WAF should not hold any keys or sensitive information
• Use a secure communication channel
• Auto scale
• Endpoint IP address (when scaling application does the WAF know
the new applications)
74. When to use it
• To prevent an application from trying to invoke a remote service or
access a shared resource if this operation is highly likely to fail
• Better user experience
75. When not to use
• Handling access to local private resources in an application, such as
in-memory data structure
• Creates an overhead
• Not a substitute for handling exceptions in the business logic of your
applications
78. Retry Pattern
• Enable an application to handle transient failures
• When the applications tries to connect to a service or network
resource
• By transparently retrying a failed operation
81. When to use it
• Use retry for only transient failure that is more than likely to resolve
themselves quickly
• Match the retry policies with the application
• Otherwise use the circuit break pattern
82. When not to use it
• Don’t cause a chain reaction to all components
• For internal exceptions caused by business logic
• Log all retry attempts to the service
83. Libraries
• Roll your own code
• Polly (http://www.thepollyproject.org/)
• Netflix (Hystrix) https://github.com/Netflix/Hystrix/wiki
86. Strangler Pattern
• Incrementally migrate a legacy system
• Gradually replacing specific pieces of functionality with new
applications and services
• Features from the legacy system are replaced by new system features
eventually
• Strangling the old system and allowing you to decommission it
89. When to use
• Gradually migrating a back-end application to a new architecture
90. When not to use
• When requests to the back-end system cannot be intercepted
• For smaller systems where the complexity of wholesale replacement
is low
91. Considerations
• Handle services and data stores that are potentially used by both new
and legacy systems.
• Make sure both can access these resources side-by-side
• When migration is complete, the strangler façade will either go away
or evolve into an adaptor for legacy clients
• Make sure the façade doesn't become a single point of failure or a
performance bottleneck.
For every 25 percent increase in problem complexity, there is a 100 percent increase in solution complexity.
There is seldom one best design solution to a software problem.
If cars were like software, they would crash twice a day for no reason, and when you called for service, they’d tell you to reinstall the engine.
