# Metrics

Source: https://docs.interop.io/manager/opentelemetry-support/metrics/index.html

## Overview

The **io.Manager** Server can be configured to export [metrics](https://opentelemetry.io/docs/concepts/signals/metrics/) via OpenTelemetry.

By default, the **io.Manager** Server supports exporting metrics to an [OpenTelemetry Collector](https://opentelemetry.io/docs/collector/). It's also possible to provide your own [custom](#customization) metrics exporter and metrics reader pointing to a different backend service.

The **io.Manager** Server publishes a set of [metrics](#available_metrics) which you can enable or disable and configure individually.

## Enabling Metrics Exports

Publishing metrics data is disabled by default. To enable publishing metrics, you must [enable OpenTelemetry support](https://docs.interop.io/manager/opentelemetry-support/overview/index.md#enabling_opentelemetry_support) in the **io.Manager** Server and explicitly enable the metrics feature via the configuration object for initializing the **io.Manager** Server, or via environment variables, depending on your [deployment](https://docs.interop.io/manager/deployment/index.md) approach.

### Environment Variables

To enable and configure publishing metrics, register the following environment variables with the proper values. The `API_OTEL_METRICS_ENABLED` environment variable must be set to `true`:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` | If `true` (default), will enable publishing of all [available metrics](#available_metrics). |
| `API_OTEL_METRICS_ENABLED` | If `true`, will enable publishing OpenTelemetry metrics. Defaults to `false`. |
| `API_OTEL_METRICS_PUBLISH_INTERVAL` | Interval in milliseconds at which the metrics reader will collect metrics. Passed to the [`PeriodicExportingMetricReader`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_sdk-metrics.PeriodicExportingMetricReader.html) constructor. This is the default metrics reader used by the **io.Manager** Server. Ignored when a [custom metrics reader](#customization-metrics_reader) is used. Defaults to `5000`. |
| `API_OTEL_METRICS_URL` | URL pointing to an [OpenTelemetry Collector](https://opentelemetry.io/docs/collector/) where the generated metrics will be sent via HTTP. Passed to the [`OTLPMetricExporter`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_exporter-metrics-otlp-http.OTLPMetricExporter.html) constructor. This is the default metrics exporter used by the **io.Manager** Server. Required if using the default metrics exporter and metrics reader. Ignored when either a [custom metrics exporter](#customization-metrics_exporter) or a [custom metrics reader](#customization-metrics_reader) is used. |

The following example demonstrates how to [enable OpenTelemetry support](https://docs.interop.io/manager/opentelemetry-support/overview/index.md#enabling_opentelemetry_support), how to enable publishing metrics, and how to configure the interval for publishing metrics:

```cmd
# Enabling OpenTelemetry support.
API_OTEL_ENABLED=true
API_OTEL_RESOURCE_SERVICE_NAME=io-manager

# Enabling and configuring metrics.
API_OTEL_METRICS_ENABLED=true
API_OTEL_METRICS_URL=http://localhost:4318/v1/metrics
API_OTEL_METRICS_PUBLISH_INTERVAL=10000
```

### Configuration Object

To enable publishing metrics, use the `metrics` property under the `otel` top-level key of the optional `Config` object for initializing the **io.Manager** Server.

The following example demonstrates how to [enable OpenTelemetry support](https://docs.interop.io/manager/opentelemetry-support/overview/index.md#enabling_opentelemetry_support), how to enable publishing metrics, and how to configure the interval for publishing metrics:

```javascript
import { start } from "@interopio/manager";

const config = {
    // Enabling OpenTelemetry support.
    otel: {
        enabled: true,
    	resource: {
    	    serviceName: "io-manager"
    	},
        // Enabling and configuring metrics.
        metrics: {
    	    enabled: true,
    	    url: "http://localhost:4318/v1/metrics",
            publishInterval: 10000
    	}
    }
};

const server = await start(config);
```

The `metrics` object has the following properties:

| Property | Type | Description |
|----------|------|-------------|
| `customExporter` | `object` | [`PushMetricExporter`](https://open-telemetry.github.io/opentelemetry-js/interfaces/_opentelemetry_sdk-metrics.PushMetricExporter.html) instance of a [custom metrics exporter](#customization-metrics_exporter) to be used instead of the default metrics exporter. Ignored when a [custom metrics reader](#customization-metrics_reader) is used. |
| `customReader` | `object` | [`MetricReader`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_sdk-metrics.MetricReader.html) instance of a [custom metrics reader](#customization-metrics_reader) to be used instead of the default metrics reader. |
| `defaultMetricsEnabled` | `boolean` | If `true` (default), will enable publishing of all [available metrics](#available_metrics). |
| `enabled` | `boolean` | If `true`, will enable publishing OpenTelemetry metrics. Defaults to `false`. |
| `metrics` | `object[]` | List of metric definition objects with configuration for the available metrics. |
| `publishInterval` | `number` | Interval in milliseconds at which the metrics reader will collect metrics. Passed to the [`PeriodicExportingMetricReader`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_sdk-metrics.PeriodicExportingMetricReader.html) constructor. This is the default metrics reader used by the **io.Manager** Server. Ignored when a [custom metrics reader](#customization-metrics_reader) is used. Defaults to `5000`. |
| `url` | `string` | URL pointing to an [OpenTelemetry Collector](https://opentelemetry.io/docs/collector/) where the generated metrics will be sent via HTTP. Passed to the [`OTLPMetricExporter`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_exporter-metrics-otlp-http.OTLPMetricExporter.html) constructor. This is the default metrics exporter used by the **io.Manager** Server. Required if using the default metrics exporter and metrics reader. Ignored when either a [custom metrics exporter](#customization-metrics_exporter) or a [custom metrics reader](#customization-metrics_reader) is used. |

## Available Metrics

The **io.Manager** Server exports the following metrics:

| Metric | Instrument Type | Description |
|--------|-----------------|-------------|
| `"http.server.active_requests"` | `UpDownCounter` | Number of active HTTP server requests. |
| `"http.server.request.body.size"` | `Histogram` | Size of HTTP server request bodies. |
| `"http.server.request.duration"` | `Histogram` | Duration of HTTP server requests. |
| `"http.server.response.body.size"` | `Histogram` | Size of HTTP server response bodies. |
| `"io_manager.active_sessions"` | `Gauge` | Total number of sessions that have made requests within a past interval. This interval is defined by the `inactiveSessionTimeout` metric property, it's measured in seconds and is configurable. |
| `"io_manager.db.operation.retries"` | `Counter` | Number of transient-failure retries of database transactions and standalone reads. *Available since **io.Manager** 4.0.* |
| `"io_manager.db.transaction.duration"` | `Histogram` | Duration of database transactions opened by the server, including transient-failure retries. *Available since **io.Manager** 4.0.* |

All available metrics are enabled by default. It's possible to disable all available metrics and explicitly enable and configure individual ones via the configuration object for initializing the **io.Manager** Server, or via environment variables, depending on your [deployment](https://docs.interop.io/manager/deployment/index.md) approach. Each metric has specific configurable properties (for more details about each individual metric, see the respective metric section).

To disable all available metrics via environment variables, set the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` variable to `false`. To explicitly enable and configure individual metrics, use the respective environment variables listed in the sections describing the individual metrics.

The following example demonstrates how to disable all available metrics and explicitly enable and configure the `"io_manager.active_sessions"` metric via environment variables:

```cmd
# Enabling OpenTelemetry support.
API_OTEL_ENABLED=true
API_OTEL_RESOURCE_SERVICE_NAME=io-manager

# Enabling metrics.
API_OTEL_METRICS_ENABLED=true
API_OTEL_METRICS_URL=http://localhost:4318/v1/metrics

# Disabling all available metrics.
API_OTEL_METRICS_DEFAULT_METRICS_ENABLED=false

# Enabling and configuring the `"io_manager.active_sessions"` metric.
API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_ENABLED=true
API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_PUBLISH_INTERVAL=45000
```

To disable all available metrics via the configuration object for initializing the **io.Manager** Server, set the `defaultMetricsEnabled` property of the `metrics` object to `false`. To explicitly enable and configure individual metrics, use the `metrics` property of the `metrics` object. It accepts a list of metrics definition objects. To specify the metric you want to enable and configure, provide the metric name as a value to the `type` property of the metrics definition object.

The following example demonstrates how to disable all available metrics and explicitly enable and configure the `"io_manager.active_sessions"` metric:

```javascript
import { start } from "@interopio/manager";

const config = {
    otel: {
        enabled: true,
        resource: {
    	    serviceName: "io-manager"
    	},
    	metrics: {
    	    enabled: true,
    	    url: "http://localhost:4318/v1/metrics",
            // Disabling all available metrics
    	    defaultMetricsEnabled: false,
            // Enabling and configuring the `"io_manager.active_sessions"` metric.
    	    metrics: [
    	        {
    	            type: "io_manager.active_sessions",
    	            enabled: true,
                    publishInterval: 45000
    	        }
    	    ]
    	}
    }
};

const server = await start(config);
```

The following sections describe each individual metric published by the **io.Manager** Server.

### http.server.active_requests

The instrument type of the [`"http.server.active_requests"`](https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#metric-httpserveractive_requests) metric is `UpDownCounter`.

The following environment variables are available for configuring the `"http.server.active_requests"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_HTTP_ACTIVE_REQUESTS_DESCRIPTION` | Description for the metric. Defaults to `"Number of active HTTP server requests."`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_ACTIVE_REQUESTS_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_ACTIVE_REQUESTS_NAME` | Name for the metric. May be used in visualization tools. Defaults to `http.server.active_requests`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_ACTIVE_REQUESTS_UNIT` | Unit for the metric values. Defaults to `{request}`. |

The following properties are available for configuring the `"http.server.active_requests"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `description` | `string` | Description for the metric. Defaults to `"Number of active HTTP server requests."`. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"http.server.active_requests"`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"http.server.active_requests"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"{request}"`. |

### http.server.request.body.size

The instrument type of the [`"http.server.request.body.size"`](https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#metric-httpserverrequestbodysize) metric is `Histogram`.

The following environment variables are available for configuring the `"http.server.request.body.size"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_BODY_SIZE_BUCKETS` | Histogram bucket boundaries. Defaults to `[1024, 10240, 102400, 1048576, 10485760, 104857600]`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_BODY_SIZE_DESCRIPTION` | Description for the metric. Defaults to `"Size of HTTP server request bodies."`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_BODY_SIZE_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_BODY_SIZE_NAME` | Name for the metric. May be used in visualization tools. Defaults to `http.server.request.body.size`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_BODY_SIZE_UNIT` | Unit for the metric values. Defaults to `By`. |

The following properties are available for configuring the `"http.server.request.body.size"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `buckets` | `number[]` | Histogram bucket boundaries. Defaults to `[1024, 10240, 102400, 1048576, 10485760, 104857600]`. |
| `description` | `string` | Description for the metric. Defaults to `"Size of HTTP server request bodies."`. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"http.server.request.body.size"`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"http.server.request.body.size"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"By"`. |

### http.server.request.duration

The instrument type of the [`"http.server.request.duration"`](https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#metric-httpserverrequestduration) metric is `Histogram`.

The following environment variables are available for configuring the `"http.server.request.duration"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_DURATION_BUCKETS` | Histogram bucket boundaries. Defaults to `[0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10]`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_DURATION_DESCRIPTION` | Description for the metric. Defaults to `"Duration of HTTP server requests."`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_DURATION_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_DURATION_NAME` | Name for the metric. May be used in visualization tools. Defaults to `http.server.request.duration`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_REQUEST_DURATION_UNIT` | Unit for the metric values. Defaults to `s`. |

The following properties are available for configuring the `"http.server.request.duration"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `buckets` | `number[]` | Histogram bucket boundaries. Defaults to `[0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10]`. |
| `description` | `string` | Description for the metric. Defaults to `"Duration of HTTP server requests."`. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"http.server.request.duration"`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"http.server.request.duration"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"s"`. |

### http.server.response.body.size

The instrument type of the [`"http.server.response.body.size"`](https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#metric-httpserverresponsebodysize) metric is `Histogram`.

The following environment variables are available for configuring the `"http.server.response.body.size"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_HTTP_RESPONSE_BODY_SIZE_BUCKETS` | Histogram bucket boundaries. Defaults to `[1024, 10240, 102400, 1048576, 10485760, 104857600]`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_RESPONSE_BODY_SIZE_DESCRIPTION` | Description for the metric. Defaults to `"Size of HTTP server response bodies."`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_RESPONSE_BODY_SIZE_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_RESPONSE_BODY_SIZE_NAME` | Name for the metric. May be used in visualization tools. Defaults to `http.server.response.body.size`. |
| `API_OTEL_METRICS_DEFINITIONS_HTTP_RESPONSE_BODY_SIZE_UNIT` | Unit for the metric values. Defaults to `By`. |

The following properties are available for configuring the `"http.server.response.body.size"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `buckets` | `number[]` | Histogram bucket boundaries. Defaults to `[1024, 10240, 102400, 1048576, 10485760, 104857600]`. |
| `description` | `string` | Description for the metric. Defaults to `"Size of HTTP server response bodies."`. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"http.server.response.body.size"`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"http.server.response.body.size"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"By"`. |

### io_manager.active_sessions

The instrument type of the `"io_manager.active_sessions"` metric is `Gauge`.

The following environment variables are available for configuring the `"io_manager.active_sessions"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_DESCRIPTION` | Description for the metric. Defaults to ```"Total number of sessions that made requests in the past `inactiveSessionTimeout` seconds."```. |
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_INACTIVE_SESSION_TIMEOUT` | Interval in seconds after which a session is considered inactive. Must be set to the same value as the `fetchInterval` property of the `server` object in the [platform configuration](https://docs.interop.io/manager/configuration/platform/index.md) (**io.Connect Desktop** or **io.Connect Browser**) for **io.Manager**. Defaults to `30`. |
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_NAME` | Name for the metric. May be used in visualization tools. Defaults to `io_manager.active_sessions`. |
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_PUBLISH_AT_STARTUP_ENABLED` | If `true` (default), the **io.Manager** Server will publish the metric at startup. |
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_PUBLISH_INTERVAL` | Interval in milliseconds at which to publish the metric. Defaults to `60000`. |
| `API_OTEL_METRICS_DEFINITIONS_ACTIVE_SESSIONS_UNIT` | Unit for the metric values. Defaults to `{session}`. |

The following properties are available for configuring the `"io_manager.active_sessions"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `description` | `string` | Description for the metric. Defaults to ```"Total number of sessions that made requests in the past `inactiveSessionTimeout` seconds."```. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `inactiveSessionTimeout` | `number` | Interval in seconds after which a session is considered inactive. Must be set to the same value as the `fetchInterval` property of the `server` object in the [platform configuration](https://docs.interop.io/manager/configuration/platform/index.md) (**io.Connect Desktop** or **io.Connect Browser**) for **io.Manager**. Defaults to `30`. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"io_manager.active_sessions"`. |
| `publishAtStartupEnabled` | `boolean` | If `true` (default), the **io.Manager** Server will publish the metric at startup. |
| `publishInterval` | `number` | Interval in milliseconds at which to publish the metric. Defaults to `60000`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"io_manager.active_sessions"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"{session}"`. |

### io_manager.db.operation.retries

Available since io.Manager 4.0

The instrument type of the `"io_manager.db.operation.retries"` metric is `Counter`.

Each increment carries an `error.type` attribute with the database error code that triggered the retry.

The following environment variables are available for configuring the `"io_manager.db.operation.retries"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_DB_OPERATION_RETRIES_DESCRIPTION` | Description for the metric. Defaults to `"Number of transient-failure retries of database transactions and standalone reads."`. |
| `API_OTEL_METRICS_DEFINITIONS_DB_OPERATION_RETRIES_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_DB_OPERATION_RETRIES_NAME` | Name for the metric. May be used in visualization tools. Defaults to `io_manager.db.operation.retries`. |
| `API_OTEL_METRICS_DEFINITIONS_DB_OPERATION_RETRIES_UNIT` | Unit for the metric values. Defaults to `{retry}`. |

The following properties are available for configuring the `"io_manager.db.operation.retries"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `description` | `string` | Description for the metric. Defaults to `"Number of transient-failure retries of database transactions and standalone reads."`. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"io_manager.db.operation.retries"`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"io_manager.db.operation.retries"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"{retry}"`. |

### io_manager.db.transaction.duration

Available since io.Manager 4.0

The instrument type of the `"io_manager.db.transaction.duration"` metric is `Histogram`.

Each measurement carries an `io_manager.db.transaction.outcome` attribute with the outcome of the transaction - `commit` or `rollback`.

The following environment variables are available for configuring the `"io_manager.db.transaction.duration"` metric:

| Environment Variable | Description |
|----------------------|-------------|
| `API_OTEL_METRICS_DEFINITIONS_DB_TRANSACTION_DURATION_BUCKETS` | Histogram bucket boundaries. Defaults to `[0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10]`. |
| `API_OTEL_METRICS_DEFINITIONS_DB_TRANSACTION_DURATION_DESCRIPTION` | Description for the metric. Defaults to `"Duration of database transactions opened by the server, including transient-failure retries."`. |
| `API_OTEL_METRICS_DEFINITIONS_DB_TRANSACTION_DURATION_ENABLED` | If `true`, will enable publishing the metric. Defaults to the value of the `API_OTEL_METRICS_DEFAULT_METRICS_ENABLED` environment variable. |
| `API_OTEL_METRICS_DEFINITIONS_DB_TRANSACTION_DURATION_NAME` | Name for the metric. May be used in visualization tools. Defaults to `io_manager.db.transaction.duration`. |
| `API_OTEL_METRICS_DEFINITIONS_DB_TRANSACTION_DURATION_UNIT` | Unit for the metric values. Defaults to `s`. |

The following properties are available for configuring the `"io_manager.db.transaction.duration"` metric via the configuration object for initializing the **io.Manager** Server:

| Property | Type | Description |
|----------|------|-------------|
| `buckets` | `number[]` | Histogram bucket boundaries. Defaults to `[0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10]`. |
| `description` | `string` | Description for the metric. Defaults to `"Duration of database transactions opened by the server, including transient-failure retries."`. |
| `enabled` | `boolean` | If `true`, will enable publishing the metric. Defaults to the value of the `defaultMetricsEnabled` property of the `metrics` object. |
| `name` | `string` | Name for the metric. May be used in visualization tools. Defaults to `"io_manager.db.transaction.duration"`. |
| `type` | `string` | **Required.** The metric type. Must be set to `"io_manager.db.transaction.duration"`. |
| `unit` | `string` | Unit for the metric values. Defaults to `"s"`. |

## Customization

### Metrics Exporter

The **io.Manager** Server provides an out-of-the-box implementation of an [`OTLPMetricExporter`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_exporter-metrics-otlp-http.OTLPMetricExporter.html) for sending metrics to an [OpenTelemetry Collector](https://opentelemetry.io/docs/collector/) via HTTP.

For more advanced scenarios, it's possible to provide an instance of a custom metrics exporter by using the `customExporter` property of the `metrics` object in the [configuration object](#enabling_metrics_exports-configuration_object) for initializing the **io.Manager** Server.

> ⚠️ *Note that it isn't possible to provide a custom metrics exporter via environment variables.*

> ℹ️ *For a complete example of creating a custom metrics exported, see the [OpenTelemetry Custom Metrics Exporter](https://github.com/InteropIO/manager-examples/tree/main/otel-custom-metrics-exporter) example on GitHub.*

### Metrics Reader

The **io.Manager** Server provides an out-of-the-box implementation of a [`PeriodicExportingMetricReader`](https://open-telemetry.github.io/opentelemetry-js/classes/_opentelemetry_sdk-metrics.PeriodicExportingMetricReader.html) for exporting metrics periodically.

For more advanced scenarios, it's possible to provide an instance of a custom metrics reader by using the `customReader` property of the `metrics` object in the [configuration object](#enabling_metrics_exports-configuration_object) for initializing the **io.Manager** Server.

> ⚠️ *Note that it isn't possible to provide a custom metrics reader via environment variables.*

> ℹ️ *For a complete example of creating a custom metrics reader, see the [OpenTelemetry Custom Metrics Reader](https://github.com/InteropIO/manager-examples/tree/main/otel-custom-metrics-reader) example on GitHub.*