Provide service contracts per API

Implementing service contracts between API producers and consumers is vital for creating robust and reliable service-oriented architectures. These contracts ensure clear specifications, enabling teams to develop and deploy services independently while maintaining compatibility, thus enhancing the reliability of workloads.

Best Practices

Establish Clear API Service Contracts

• Define comprehensive and clear API contracts that specify the inputs, outputs, expected behaviors, and error handling. This is important to ensure both producers and consumers understand the expectations and requirements for integration.
• Use machine-readable formats such as OpenAPI or Swagger to document APIs, making it easier for consumers to automatically generate client libraries and ensure compliance with the contract.
• Implement versioning for APIs to allow backward compatibility. This helps to ensure that existing consumers can continue using the API while new features can be added, reducing the risk of breaking changes.
• Encourage collaboration between service teams and stakeholders to agree on API contracts, which fosters better communication and understanding of service responsibilities.
• Utilize automated testing frameworks to validate that the API implementations adhere to the defined contracts, minimizing the chance of integration issues.

Questions to ask your team

• Have you defined clear service contracts for each API that your architecture exposes?
• How do you ensure that all teams adhere to the defined service contracts?
• What versioning strategy do you have in place for your API contracts?
• How do you manage backward compatibility for APIs during updates?
• What documentation processes are in place for maintaining service contracts?
• How often do you review and update your API contracts to adapt to new requirements?
• Can you provide examples of how service contracts have improved the reliability of your workloads?

Who should be doing this?

API Product Owner

• Define and manage service contracts for APIs
• Ensure alignment of API features with business needs
• Facilitate communication between API producers and consumers
• Oversee versioning strategy for service contracts

API Developer

• Implement the APIs according to the defined service contracts
• Ensure that the APIs are backward compatible with previous versions
• Document API functionality and changes
• Monitor API performance and reliability

Quality Assurance Engineer

• Test APIs against defined service contracts
• Validate backward compatibility during API updates
• Ensure that the APIs meet reliability standards
• Report and assist in resolving API issues

DevOps Engineer

• Automate deployment processes for API updates
• Monitor API performance and uptime metrics
• Implement rollback strategies for API failures
• Maintain infrastructure to support scalable API services

Technical Writer

• Create and maintain comprehensive API documentation
• Ensure that service contracts are easily understandable for consumers
• Update documentation with each version of the API
• Collaborate with developers to capture API changes accurately

What evidence shows this is happening in your organization?

• API Contract Template: A standardized template for documenting service contracts, including specifications for endpoints, request/response formats, versioning details, and usage guidelines.
• API Versioning Strategy Guide: An internal guide outlining the strategies for versioning APIs, including best practices for backward compatibility and a process for phasing out older versions.
• Service Contract Dashboard: A visual dashboard that tracks the status of API contracts across various services, showing versioning history, consumer adoption rates, and compliance with service contracts.
• API Documentation Playbook: A playbook that provides guidelines for service teams on how to document their APIs in alignment with the established service contracts, ensuring clarity and consistency.
• Reliability Checklist for API Development: A checklist used by development teams to ensure that newly developed APIs adhere to the reliability and contract specifications before deployment.

Cloud Services

AWS

• AWS API Gateway: AWS API Gateway allows you to create, publish, maintain, monitor, and secure APIs at any scale. It supports API versioning and can help manage API contracts effectively.
• Amazon CloudWatch: CloudWatch provides monitoring and logging services that help you track API usage and performance, ensuring that your contracts are being adhered to and that the API is reliable.
• AWS Lambda: AWS Lambda enables you to run code in response to API requests without provisioning servers, making it easier to implement microservices that follow specified contracts.

Azure

• Azure API Management: Azure API Management allows you to create consistent and modern API gateways for back-end services with features for versioning and contract management.
• Azure Application Insights: Application Insights provides powerful monitoring tools for your APIs, helping to ensure that they perform reliably and adhere to service contracts.
• Azure Functions: Azure Functions allows you to execute code in a serverless environment, which can simplify the deployment of microservices that follow defined API contracts.

Google Cloud Platform

• Apigee API Management: Apigee provides a platform to manage APIs with capabilities for versioning and contract tracking, essential for maintaining service reliability.
• Google Cloud Monitoring: Cloud Monitoring helps you gain visibility into your API performance, ensuring adherence to service contracts and reliability.
• Google Cloud Functions: Cloud Functions allows you to deploy single-purpose functions, which can be part of a microservices architecture meeting specific API contracts.

Question: How do you design your workload service architecture?
Pillar: Reliability (Code: REL)