API Retirement Strategies

Retirement Lifecycle

The retirement of an API version follows two distinct, sequential phases: Deprecation and Sunsetting.

Table of Contents

• Retirement Lifecycle
• Table of Contents
• Best Practices for Communication
• Operational Steps
• Best practices

Best Practices for Communication

Effective communication is the most critical component of a successful deprecation policy.

1. Early and Multi-Channel Notification

• Initial Announcement: As soon as the decision is made, announce it via email newsletters, developer portals/blogs, and your change log.
• Clear Timelines: Specify the Deprecation Date and the final Sunset Date (EoL). A grace period of at least 6-12 months is highly recommended, especially for public APIs with large user bases.
• Reasoning and Alternatives: Always explain why the version is being retired (e.g., security, performance, new features) and provide clear migration guides to the new version.

2. Technical Communication via HTTP Headers

Utilize standard HTTP response headers for machine-readable communication, enabling clients to automatically detect and log deprecation status.

Ensure that response sent from those APIs are having Deprecation and Sunset headers with information such as sunset date.

The most effective way to add Deprecation and Sunsetheaders is by intercepting the request/response flow at API Gateway (or a similar edge component like a load balancer or service mesh).

Advantages of using API Gateway

// Example of setting Headers in a Spring Boot Controller (V1 endpoint)
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;

@GetMapping("/v1/person")
public ResponseEntity<PersonV1> getPersonV1() {
    return ResponseEntity.ok()
            .header("Deprecation", "true") // A simple boolean/date
            .header("Sunset", "Sat, 31 Dec 2025 23:59:59 GMT")
            .header("Link", "<https://docs.yourcompany.com/v1-migration>; rel=\"deprecation\"")
            .body(new PersonV1("Deprecated V1 Data"));
}

Operational Steps

Monitor and Track Usage

• Use API Gateway logs or internal metrics to monitor traffic to the deprecated version.
• The goal is to see usage gradually drop over the deprecation period. If usage remains high close to the Sunset Date, you may need to reach out to specific high-volume users.

Update Documentation and SDKs

• Mark the old version as deprecated: true in your OpenAPI (Swagger) specification.
• Add a prominent, non-dismissible banner on the deprecated version’s documentation page, linking directly to the new version’s documentation and the migration guide.
• Update any official SDKs or client libraries to target the new API version by default and emit warnings if they are still configured to use the old version.

Post-Sunset Action

• Retire: On the Sunset Date, disable the API endpoint. You should serve a 410 Gone HTTP status code to clearly signal that the resource is permanently unavailable, rather than a 404 Not Found, which implies it never existed.
• Code Cleanup: Only after the Sunset Date should you proceed to safely remove the deprecated code from your microservice, realizing the operational cost savings.

Note:
By formalizing these steps, you build a consistent process that respects your clients’ time and protects your reputation.

Best practices

• Deprecation Policy:
  • Add a formal deprecation strategy (e.g., set a Deprecation or Sunset HTTP header) to communicate when an old version will be retired.