---
title: "otelcol.connector.spanlogs | Grafana Agent documentation"
description: "Learn about otelcol.connector.spanlogs"
---

# otelcol.connector.spanlogs

`otelcol.connector.spanlogs` accepts traces telemetry data from other `otelcol` components and outputs logs telemetry data for each span, root, or process. This allows you to automatically build a mechanism for trace discovery.

> **NOTE**: `otelcol.connector.spanlogs` is a custom component unrelated to any components from the OpenTelemetry Collector. It is based on the `automatic_logging` component in the [traces](../../../../static/configuration/traces-config/) subsystem of the Agent static mode.

You can specify multiple `otelcol.connector.spanlogs` components by giving them different labels.

## Usage

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
otelcol.connector.spanlogs "LABEL" {
  output {
    logs    = [...]
  }
}
```

## Arguments

`otelcol.connector.spanlogs` supports the following arguments:

Expand table

| Name                 | Type           | Description                                   | Default | Required |
|----------------------|----------------|-----------------------------------------------|---------|----------|
| `spans`              | `bool`         | Log one line per span.                        | `false` | no       |
| `roots`              | `bool`         | Log one line for every root span of a trace.  | `false` | no       |
| `processes`          | `bool`         | Log one line for every process.               | `false` | no       |
| `span_attributes`    | `list(string)` | Additional span attributes to log.            | `[]`    | no       |
| `process_attributes` | `list(string)` | Additional process attributes to log.         | `[]`    | no       |
| `labels`             | `list(string)` | A list of keys that will be logged as labels. | `[]`    | no       |

The values listed in `labels` should be the values of either span or process attributes.

> **WARNING**: Setting `spans` to `true` could lead to a high volume of logs.

## Blocks

The following blocks are supported inside the definition of `otelcol.connector.spanlogs`:

Expand table

| Hierarchy | Block                         | Description                                       | Required |
|-----------|-------------------------------|---------------------------------------------------|----------|
| overrides | [overrides](#overrides-block) | Overrides for keys in the log body.               | no       |
| output    | [output](#output-block)       | Configures where to send received telemetry data. | yes      |

### overrides block

The `overrides` block configures overrides for keys that will be logged in the body of the log line.

The following attributes are supported:

Expand table

| Name                | Type     | Description                                                | Default  | Required |
|---------------------|----------|------------------------------------------------------------|----------|----------|
| `logs_instance_tag` | `string` | Indicates if the log line is for a span, root, or process. | `traces` | no       |
| `service_key`       | `string` | Log key for the service name of the resource.              | `svc`    | no       |
| `span_name_key`     | `string` | Log key for the name of the span.                          | `span`   | no       |
| `status_key`        | `string` | Log key for the status of the span.                        | `status` | no       |
| `duration_key`      | `string` | Log key for the duration of the span.                      | `dur`    | no       |
| `trace_id_key`      | `string` | Log key for the trace ID of the span.                      | `tid`    | no       |

### output block

The `output` block configures a set of components to forward resulting telemetry data to.

The following arguments are supported:

Expand table

| Name   | Type                     | Description                        | Default | Required |
|--------|--------------------------|------------------------------------|---------|----------|
| `logs` | `list(otelcol.Consumer)` | List of consumers to send logs to. | `[]`    | no       |

You must specify the `output` block, but all its arguments are optional. By default, telemetry data is dropped. Configure the `logs` argument accordingly to send telemetry data to other components, .

## Exported fields

The following fields are exported and can be referenced by other components:

Expand table

| Name    | Type               | Description                                                      |
|---------|--------------------|------------------------------------------------------------------|
| `input` | `otelcol.Consumer` | A value that other components can use to send telemetry data to. |

`input` accepts `otelcol.Consumer` data for any telemetry signal (metrics, logs, or traces).

## Component health

`otelcol.connector.spanlogs` is only reported as unhealthy if given an invalid configuration.

## Debug information

`otelcol.connector.spanlogs` does not expose any component-specific debug information.

## Example

The following configuration sends logs derived from spans to Loki.

Additionally, `otelcol.processor.attributes` is configured with a “hint” so that `otelcol.exporter.loki` promotes the span’s “attribute1” attribute to a Loki label.

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
otelcol.receiver.otlp "default" {
  grpc {}

  output {
    traces = [otelcol.connector.spanlogs.default.input]
  }
}

otelcol.connector.spanlogs "default" {
  spans              = true
  roots              = true
  processes          = true
  labels             = ["attribute1", "res_attribute1"]
  span_attributes    = ["attribute1"]
  process_attributes = ["res_attribute1"]

  output {
    logs = [otelcol.processor.attributes.default.input]
  }
}

otelcol.processor.attributes "default" {
  action {
    key = "loki.attribute.labels"
    action = "insert"
    value = "attribute1"
  }

  output {
    logs = [otelcol.exporter.loki.default.input]
  }
}

otelcol.exporter.loki "default" {
  forward_to = [loki.write.local.receiver]
}

loki.write "local" {
  endpoint {
    url = "loki:3100"
  }
}
```

For an input trace like this…

JSON ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```json
{
  "resourceSpans": [
    {
      "resource": {
        "attributes": [
          {
            "key": "service.name",
            "value": { "stringValue": "TestSvcName" }
          },
          {
            "key": "res_attribute1",
            "value": { "intValue": "78" }
          },
          {
            "key": "unused_res_attribute1",
            "value": { "stringValue": "str" }
          },
          {
            "key": "res_account_id",
            "value": { "intValue": "2245" }
          }
        ]
      },
      "scopeSpans": [
        {
          "spans": [
            {
              "trace_id": "7bba9f33312b3dbb8b2c2c62bb7abe2d",
              "span_id": "086e83747d0e381e",
              "name": "TestSpan",
              "attributes": [
                {
                  "key": "attribute1",
                  "value": { "intValue": "78" }
                },
                {
                  "key": "unused_attribute1",
                  "value": { "intValue": "78" }
                },
                {
                  "key": "account_id",
                  "value": { "intValue": "2245" }
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}
```

… the output log coming out of `otelcol.connector.spanlogs` will look like this:

JSON ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```json
{
  "resourceLogs": [
    {
      "scopeLogs": [
        {
          "log_records": [
            {
              "body": {
                "stringValue": "span=TestSpan dur=0ns attribute1=78 svc=TestSvcName res_attribute1=78 tid=7bba9f33312b3dbb8b2c2c62bb7abe2d"
              },
              "attributes": [
                {
                  "key": "traces",
                  "value": { "stringValue": "span" }
                },
                {
                  "key": "attribute1",
                  "value": { "intValue": "78" }
                },
                {
                  "key": "res_attribute1",
                  "value": { "intValue": "78" }
                }
              ]
            },
            {
              "body": {
                "stringValue": "span=TestSpan dur=0ns attribute1=78 svc=TestSvcName res_attribute1=78 tid=7bba9f33312b3dbb8b2c2c62bb7abe2d"
              },
              "attributes": [
                {
                  "key": "traces",
                  "value": { "stringValue": "root" }
                },
                {
                  "key": "attribute1",
                  "value": { "intValue": "78" }
                },
                {
                  "key": "res_attribute1",
                  "value": { "intValue": "78" }
                }
              ]
            },
            {
              "body": {
                "stringValue": "svc=TestSvcName res_attribute1=78 tid=7bba9f33312b3dbb8b2c2c62bb7abe2d"
              },
              "attributes": [
                {
                  "key": "traces",
                  "value": { "stringValue": "process" }
                },
                {
                  "key": "res_attribute1",
                  "value": { "intValue": "78" }
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}
```

## Compatible components

`otelcol.connector.spanlogs` can accept arguments from the following components:

- Components that export [OpenTelemetry `otelcol.Consumer`](../../compatibility/#opentelemetry-otelcolconsumer-exporters)

`otelcol.connector.spanlogs` has exports that can be consumed by the following components:

- Components that consume [OpenTelemetry `otelcol.Consumer`](../../compatibility/#opentelemetry-otelcolconsumer-consumers)

> Note
> 
> Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.