A simple framework that helps setup and export metrics, logs, (and in the future distributed tracing) using Open Telemetry for your component. Logs are instrumented using the standard [log crate macros] (https://docs.rs/log/latest/log/), written to stderr in the syslog format, and available to exported to log repositories that support OTLP/gRPC. Metrics are instrumented using the [open telemetry sdk] (https://crates.io/crates/opentelemetry), can be converted to Prometheus, and available to be exported to metric repositories that support OTLP/gRPC.

The project also includes a sample app that demonstrates how to use the framework.

The framework is configurable using the Config struct to setup

• service name
• 0 or more metrics export targets, where each target is a metrics repository that supports OTLP/gRPC
• Enable Prometheus support. When enabled, the framework will translate the instrumented OTEL metrics into Prometheus metrics and provide a HTTP endpoint that can be scraped by external Prometheus scrapers
• Enable metrics to be emitted to stdout. These will show up as pretty printed JSON
• 0 or more Log export targets, where each target is a log repository that supports OTLP/gRPC.
• Enable logs to be emitted to stderr. These will show up as logs in the syslog format.

Do the following as early as you can in your control flow

// Configure
let metric_targets = vec![MetricsExportTarget {
        url: "http:https://localhost:4317".to_string(),
        interval_secs: 30,
        timeout: 15,
        temporality: Temporality::Cumulative, // Set to one of Some(Temporality::Cumulative) or Some(Temporality::Delta) or None (which defaults to Cumulative)
    }];

let log_targets = vec![LogsExportTarget {
    url: "http:https://localhost:4317".to_string(),
    interval_secs: 10,
    timeout: 15,
    export_severity: Some(Severity::Error), // Applies an additional filter at the exporter level. This can be set to `None` if no additional filtering is required.
}];

// Setup Prometheus if needed.
let prometheus_config = Some(PrometheusConfig { port: 9090 });

let config = Config {
    service_name: "myapp".to_owned(),
    emit_metrics_to_stdout: true,
    emit_logs_to_stderr: true,
    metrics_export_targets: Some(metric_targets),
    log_export_targets: Some(log_targets),
    level: "info,hyper=off".to_owned(),
    resource_attributes: Some(vec![Attribute {
        key: "resource_key1".to_owned(),
        value: "1".to_owned(),
    }]),
    prometheus_config,
    ..Config::default()
};

let otel_long_running_task = Otel::new(config).run();

// Drive the task using something like

 _ = tokio::join!(otel_long_running_task);

This initializes a static item STATIC_METRICS of type StaticMetrics that you can tweak to instrument metrics for you code.

// Add a metric to StaticMetrics
pub struct StaticMetrics {
    pub requests: Counter<u64>,
    ...

// Initialize the metric
    let meter = global::meter_provider().meter(METER_NAME);
    StaticMetrics {
        requests: meter.u64_counter("requests").init(),
        ...
    }

// add a data point where needed
 STATIC_METRICS.requests.add(1, &[]);

For log instrumentation, use the standard log::crate macros.

Traces: TBD

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