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api-log

Event-driven API call logging for Spring Boot. Async event pipeline + PostgreSQL JSONB. Log every outbound call without slowing the request path.

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At a glance

Drop the starter on your classpath and your service automatically logs every outbound HTTP call — request, response, status code, errors, retries — to PostgreSQL. The HTTP call doesn't wait for the log write; events are dispatched asynchronously.

@Service
public class UserService {

    private final RestApiClientUtil api;

    public UserService(RestApiClientUtil api) {
        this.api = api;
    }

    public User createUser(User newUser) {
        // The HTTP call is synchronous and returns immediately.
        // Three log rows land in api_log behind the scenes: INITIATED, then SUCCESS or ERROR.
        return api.postSyncTyped("/api/users", newUser, User.class);
    }
}

A single call writes to the api_log table:

SELECT event_type, endpoint, status_code, timestamp FROM api_log ORDER BY id DESC LIMIT 3;

 event_type | endpoint     | status_code | timestamp
------------+--------------+-------------+----------------------
 SUCCESS    | /api/users   |         201 | 2026-05-18 10:02:14
 INITIATED  | /api/users   |             | 2026-05-18 10:02:14

Bodies (payload, response, error_message) are stored as JSONB — queryable with ->, ->>, and GIN indexes. No more "we don't know what we sent to that vendor".

What you get

  • Non-blocking by design

    Log writes happen on a separate thread via ApplicationEventPublisher. Your HTTP call returns the moment the response arrives — the log row is persisted after.

  • PostgreSQL JSONB storage

    Request bodies, response bodies, and error details are stored as JSONB. Index with GIN, query with ->, ->>, jsonb_path_query. Schema-less where it matters, structured where you need it.

  • Retry-aware

    Integrates with Spring Retry. Each failed retry produces its own RETRY_ERROR row with retry_count — full timeline of every attempt.

  • Virtual Threads ready

    Designed for Java 21+ async. Compatible with spring.threads.virtual.enabled=true — low memory footprint, high concurrency.

  • Drop-in starter

    Auto-configuration registers ApiEventListener, ApiLogService, and RestApiClientUtil behind @ConditionalOnMissingBean. Override any of them by declaring your own.

  • Production-tested

    Used in Devslab's own SaaS infrastructure before open-sourcing. 31 tests including PostgreSQL integration tests via Testcontainers.

When to use this

Reach for api-log when you need durable, queryable history of outbound API calls — for debugging vendor integrations, compliance audits, billing reconciliation, or producing customer-facing usage reports.

Reach for something else when you only need ephemeral observability (use OpenTelemetry + a trace backend) or fire-and-forget transport logs (just log to stdout and ship to a log aggregator).

Architecture

Caller code
   ↓
RestApiClientUtil  (or your own HTTP client)
   ↓ publishEvent
ApplicationEventPublisher
   ↓ @EventListener (async)
ApiEventListener
   ↓
ApiLogService
   ↓
ApiLogRepository  (JPA)
   ↓
PostgreSQL  (api_log · JSONB columns)

Every call produces at least two rows: INITIATED (fired immediately) and a terminal row (SUCCESS, ERROR, or RETRY_ERROR). All four event types correlate via request_id, so you can reconstruct the full timeline of any call with a single query.

Next steps