prometheus

Expose metrics via a Prometheus-compatible endpoint using the metrics crate.

!!! note "Feature Flag Required" This metrics backend requires the prometheus feature to be enabled when building fiddler.

cargo build --features prometheus

BasicFull Example

metrics:
  prometheus: {}

label: My Pipeline
metrics:
  prometheus: {}
input:
  stdin: {}
processors:
  - noop: {}
output:
  stdout: {}

Exposed Metrics

The following Prometheus metrics are exposed:

Counters

Metric Name	Description
fiddler_messages_received_total	Total messages received from input
fiddler_messages_completed_total	Messages successfully processed through all outputs
fiddler_messages_filtered_total	Messages intentionally filtered/dropped by processors
fiddler_messages_process_errors_total	Messages that encountered processing errors
fiddler_messages_output_errors_total	Messages that encountered output errors
fiddler_streams_started_total	Number of streams started
fiddler_streams_completed_total	Number of streams completed
fiddler_duplicates_rejected_total	Duplicate messages rejected
fiddler_stale_entries_removed_total	Stale entries cleaned up
fiddler_input_bytes_total	Total bytes received from input
fiddler_output_bytes_total	Total bytes written to output

Gauges

Metric Name	Description
fiddler_messages_in_flight	Current number of messages being processed
fiddler_throughput_per_second	Current throughput in messages per second
fiddler_bytes_per_second	Current throughput in bytes per second
fiddler_latency_avg_ms	Average message processing latency in milliseconds
fiddler_latency_min_ms	Minimum message processing latency in milliseconds
fiddler_latency_max_ms	Maximum message processing latency in milliseconds

Scraping Metrics

The Prometheus exporter uses the default configuration from metrics-exporter-prometheus. Metrics are typically available at http://localhost:9000/metrics (default port).

Example Prometheus Configuration

scrape_configs:
  - job_name: 'fiddler'
    static_configs:
      - targets: ['localhost:9000']

Fields

Currently, the prometheus backend accepts an empty configuration object. Future versions may support additional configuration options such as:

• Custom port binding
• Custom endpoint path
• Default labels

Example Future Configuration (Not Yet Implemented)

metrics:
  prometheus:
    port: 9090
    path: /metrics
    labels:
      environment: production
      service: my-pipeline