Consumer Driven Contracts for microservices
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Consumer Driven Contracts (CDC) allow consumers to define contracts that specify the expectations of APIs produced by services. This helps drive the evolution of those APIs while maintaining backward and forward compatibility. Spring Cloud Contract provides tools for implementing CDC in Spring applications, including generating stubs for use in integration tests to reduce the need for end-to-end testing. It demonstrates a typical CDC workflow where consumers define contracts first during development, then producers verify their code against those contracts before deployment.
Consumer Driven Contracts for microservices
- 1. Consumer Driven Contracts for Microservices By Reshmi Krishna By Vinay Upadhya @reshmi9k @vinayu
- 2. About Us Reshmi Krishna ● Software Engineer ● Platform Architect, Pivotal Cloud Foundry ● Women In Tech Community Member Twitter : @reshmi9k MeetUp : Cloud-Native-New-York Vinay Upadhya ● Software Engineer ● Platform Architect, Pivotal Cloud Foundry ● Application Architecture Evangelist Twitter : @vinayu
- 3. Agenda What are Consumer Driven Contracts? What problems are we trying to solve? Spring Cloud Contract for microservices Demo
- 4. What are Consumer Driven Contracts? Internal Marketing App External Reseller App Product Search Service A P I { catalogid, name, price, manufacturer } { catalogid, name, price } Product Schema { catalogid, name, price, manufacturer, inStock } Producer Contract Expectation Consumer Contract Consumer Driven Contract
- 5. What are Consumer Driven Contracts ( CDC ) Not a new concept but becoming more prevalent in today’s world of microservices. It is a pattern for evolving services and their API’s without breaking backward or forward compatibility. CDC driven testing is TDD applied at an architectural level of the project.
- 6. What problems are we trying to solve? 1. Provide a framework for consumers to set expectations with consumer contracts and drive the producer API. 2. Producer test lifecycle includes validating consumer contracts. 3. Provide reusable producer stubs for consumers to use in their integration tests. 4. Minimize E2E integration tests.
- 7. Spring Cloud Contract Spring Cloud Contract provides support for CDC and service schemas in Spring Apps. Being part of Spring Cloud it can help stub out Spring Cloud components like Eureka, Consul etc. Comprised of three main projects :- Spring Cloud Contract Verifier : Library on server side to test if the server isn’t breaking any consumer contracts. Spring Cloud Contract Wiremock : Wrapper around wiremock to help start stubs with wiremock json stubs. Spring Cloud Contract Stub Runner : Helper library to pull stubs from maven and run them
- 8. What is a contract?
- 9. Demo I want to login Can Reshmi/123 login ? YES !!!! OK
- 10. Demo I want to login Can Vinay/321 login ? No !!!! NOT_OKAY
- 11. Typical CDC Flow Consumer Phase 1 Producer Phase Consumer Phase 2 Consumer Offline Work Producer Implementing Feature Consumer Online Work
- 12. Consumer Flow 1 (Login Client) Start TDD - writes the test for the feature Write the missing implementation Clone the Producer (LoginServerService) repository locally Define the contract locally in the repo of Producer Add the Spring Cloud Contract Verifier plugin Run the integration tests
- 13. Producer Flow (Login Server) Take over the PR Write the missing implementation that will make the autogenerated tests pass Merge PR and deploys the JARs with the app and the stubs
- 14. Consumer Flow 2 (Login Client) Switches off the Stub Runner’s offline mode once the producer uploads the stubs Configure Stub Runner by providing the URL to a repo with stubs Will have its test broken if the producer makes any breaking changes of the API
- 15. Demo : Add additional parameter to login Login Validate(UN,PWD,AC) Response Response
- 16. Resources Docs : https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html MeetUp Demo : https://github.com/reshmik/spring-cloud-contract-login-demo.git Consumer Driven Contracts (MarcinGrzejszczak) : http://www.slideshare.net/MarcinGrzejszczak/consumer-driven-contracts- and-your-microservice-architecture-67641511 More Samples : https://github.com/spring-cloud/spring-cloud-contract/tree/1.0.x/samples Talk to the SpringCloudContract Team : https://gitter.im/spring-cloud/spring-cloud-contract