Module metrics 

Prometheus metrics registry and collection helpers.

Enabled only when the metrics Cargo feature is active. Exposes a global [Registry] with the following instruments:

Name	Type	Labels	Description
osp_requests_total	Counter	method, bucket, status	Total requests
osp_request_errors_total	Counter	method, bucket, error	Total errors
osp_active_connections	Gauge	—	Current open connections
osp_request_duration_seconds	Histogram	method, bucket	Latency
osp_transfer_bytes_total	Counter	direction (rx/tx), bucket	Bytes transferred
osp_presigned_url_hits_total	Counter	bucket	Presigned URL hits
osp_memory_bytes	Gauge	—	RSS memory usage
osp_build_info	Gauge	version, rustc	Static build metadata

Statics

ACTIVE_CONNECTIONS

Number of currently active (in-flight) connections.

BUILD_INFO

Static build-info gauge — always 1, used to expose version labels.

MEMORY_BYTES

Resident Set Size in bytes (sampled at scrape time via update_memory_gauge).

PRESIGNED_URL_HITS_TOTAL

Total presigned-URL hits per bucket.

PRESIGNED_URL_REJECTED_TOTAL

Total presigned-URL rejections (usage limit exceeded).

REGISTRY

The global Prometheus registry for all OSP metrics.

REQUESTS_TOTAL

Total number of proxied requests, labelled by HTTP method, bucket and upstream response status code.

REQUEST_DURATION_SECONDS

End-to-end request latency in seconds, labelled by method and bucket.

REQUEST_ERRORS_TOTAL

Total number of requests that resulted in an error (4xx/5xx or internal).

RESPONSE_SIZE_BYTES

Response body size histogram (bytes), labelled by method and bucket.

TRANSFER_BYTES_TOTAL

Bytes transferred, labelled by direction (rx = client->proxy, tx = proxy->client) and bucket.

Functions

gather_metrics

Encode the global registry to the Prometheus text format.

init_metrics

Force all Lazy statics to initialise and record the build-info gauge.

serve_metrics

Spawn a minimal Tokio HTTP server on port that serves /metrics.

update_memory_gauge

Read /proc/self/status on Linux to obtain RSS; no-op on other platforms.