Observability - Advanced Echo Server

Observability & Monitoring

The Advanced Echo Server supports observability through Prometheus metrics, structured logging, and dedicated health check endpoints.

Prometheus Metrics

The server exposes metrics at the /metrics endpoint.

echo_requests_total

Counter of total HTTP requests

Labels: method, path, status

echo_request_duration_seconds

Histogram of request latency in seconds

No labels

echo_chaos_errors_total

Counter of chaos-induced errors

Labels: type

Health Checks

Use these endpoints to check server status:

Liveness Check

# Simple liveness check
curl http://localhost:8080/health

Readiness Check

# Readiness probe for Kubernetes
curl http://localhost:8080/ready

Server Info

# Inspect request and server metadata
curl http://localhost:8080/info
# {"server": {"hostname": "...", "version": "1.0.0", "uptime": "..."}, "request_id": "..."}

Structured Logging

Environment Variable	Description	Default	Options
`LOG_REQUESTS`	Log basic request and completion lines: `remote method path` and `remote method path - status duration`	`true`	true, false
`LOG_HEADERS`	Include request headers (exact key: value pairs as received)	`false`	true, false
`LOG_BODY`	Include request body in logs (skipped for `/sse`; truncated by `MAX_LOG_BODY_SIZE`)	`false`	true, false
`LOG_TRANSACTION`	Log a consolidated transaction block with request and response details (headers optional; bodies follow LOG_BODY/LOG_RESPONSE_BODY and are truncated by MAX_LOG_BODY_SIZE; SSE bodies omitted)	`false`	true, false
`LOG_RESPONSE`	Log response completion summary and, if enabled below, headers and/or body	`false`	true, false
`LOG_RESPONSE_HEADERS`	Include response headers in logs	`false`	true, false
`LOG_RESPONSE_BODY`	Include response body in logs (skipped for `/sse`; truncated by `MAX_LOG_BODY_SIZE`)	`false`	true, false
`MAX_LOG_BODY_SIZE`	Max bytes to log for request/response bodies (truncation)	`2048`	integer

Tip: Use X-Request-ID (auto-generated when absent) to correlate request and response logs. Completion lines include status and duration.

Sample log output

# LOG_REQUESTS=true, LOG_HEADERS=true, LOG_BODY=true, LOG_TRANSACTION=true, LOG_RESPONSE=true,
# LOG_RESPONSE_HEADERS=true, LOG_RESPONSE_BODY=true (bodies truncated by MAX_LOG_BODY_SIZE)
127.0.0.1:54321 POST /api/orders
Headers: map[Content-Type:[application/json] X-Request-Id:[abc123]]
Body: {"id":42,"item":"widget"}
cURL: curl -X POST -H "Content-Type: application/json" -H "X-Request-Id: abc123" --data '{"id":42,"item":"widget"}' http://localhost:8080/api/orders
127.0.0.1:54321 POST /api/orders - 200 12.3ms
Response headers: map[Content-Type:[application/json] X-Request-Id:[abc123]]
Response body: {"id":42,"item":"widget","echo":true}