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Cloud Design Patterns

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At Ottawa .NET User Group I had a talk on Cloud Design Patterns, External Config Pattern, Cache Aside, Federated Identity Pattern, Valet Key Pattern, Gatekeeper Pattern and the Circuit Breaker Pattern. These patterns depicts common problems in designing cloud-hosted applications and design patterns that offer guidance.

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Cloud Design Patterns

  1. 1. TaswarBhatti
  2. 2. 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 • Questions
  3. 3. 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.
  4. 4. External Configuration Pattern
  5. 5. 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
  6. 6. Typical Application
  7. 7. Storing Configuration in file
  8. 8. Multiple application
  9. 9. Problems • Configuration becomes part of deployment • Multiple applications share the same configuration • Hard to have access control over the configuration
  10. 10. External Configuration Pattern
  11. 11. 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
  12. 12. 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
  13. 13. Cloud Solution Offerings • Azure Key Vault • Vault by Hashicorp • AWS KMS • Keywhiz
  14. 14. Cache Aside Pattern
  15. 15. 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.
  16. 16. Typical Application
  17. 17. Cache Aside Pattern
  18. 18. 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
  19. 19. When not to use • Don’t use it for data that changes very often
  20. 20. 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
  21. 21. Cloud Offerings • Redis (Azure and AWS) • Memcache • Hazelcast • Elastic Cache (AWS)
  22. 22. Federated Identity Pattern
  23. 23. 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
  24. 24. Typical Application
  25. 25. Problem
  26. 26. 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
  27. 27. Federated Identity Pattern
  28. 28. 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
  29. 29. When not to use it • You already have a single application and have custom code that allows you to login
  30. 30. 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
  31. 31. Cloud Offerings • Azure AD • Gemalto STA and SAS • Amazon IAM • GCP Cloud IAM
  32. 32. Valet Key Pattern
  33. 33. 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
  34. 34. Typical Application
  35. 35. Problem
  36. 36. Valet Key Pattern
  37. 37. 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
  38. 38. When not to use it • When you need to transform the data before upload or download
  39. 39. Cloud Offerings • Azure Blob Storage • Amazon S3 • GCP Cloud Storage
  40. 40. Gatekeeper Pattern
  41. 41. 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
  42. 42. Typical Application
  43. 43. Problem
  44. 44. Gatekeeper Pattern
  45. 45. When to use it • Sensitive information (Health care, Authentication) • Distributed System where perform request validation separately
  46. 46. When not to use • Performance vs security
  47. 47. 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)
  48. 48. Circuit Breaker Pattern
  49. 49. Circuit Breaker Pattern • To handle faults that might take a variable amount of time to recover • When connecting to a remote service or resource
  50. 50. Typical Application
  51. 51. Problem
  52. 52. Circuit Breaker
  53. 53. 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
  54. 54. 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
  55. 55. Libraries • Polly (http://www.thepollyproject.org/) • Netflix (Hystrix) https://github.com/Netflix/Hystrix/wiki
  56. 56. Questions? Taswar Bhatti System Solutions Architect (Gemalto) Microsoft MVP http://taswar.zeytinsoft.com @taswarbhatti

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