OpenTelemetry event shapes

The OpenTelemetry source takes in logs, metrics, and traces, and has a separate output for each: Logs, Metrics, and Traces. It replaces three deprecated sources: OpenTelemetry Logs, OpenTelemetry Metrics, and OpenTelemetry Traces. The events the new source emits are shaped differently from those of the deprecated sources:

The deprecated sources convert each OpenTelemetry record into a Mezmo-specific event. The main payload (log body, metric, or span) goes in message, and the OpenTelemetry context (resource, scope, attributes) goes in metadata.
The OpenTelemetry source passes each record through in its original OpenTelemetry JSON form. Everything, including the resource and scope, is inside message.

Processors and destinations built for the deprecated sources won’t work with the OpenTelemetry source’s outputs unless you update their field paths or remap the events first.

At a glance

	Deprecated sources	OpenTelemetry source
Sources	One source per signal	One source with Logs, Metrics, and Traces outputs
`message`	The signal payload: log body string, Mezmo metric, or span	An envelope: `{ type, resource, scope, record }`
Resource and scope	`metadata.resource`, `metadata.scope`	`message.resource`, `message.scope`
Record attributes	`metadata.attributes` (metrics: also merged into `message.tags`)	`message.record.attributes` (metrics: `message.record.dataPoint.attributes`)
Field naming	snake case (`span_id`, `observed_timestamp`)	OpenTelemetry JSON camel case (`spanId`, `observedTimeUnixNano`)
Times	ISO 8601 strings	Nanoseconds since the Unix epoch, as strings
Numeric values	Numbers	Often strings (metric values, many attribute values)
`metadata`	OpenTelemetry context	Request metadata only, if present
`annotations`	Logs: `app`, `host`, `level`. Metrics and traces: none	`app` and `host` for all three signals
Event `timestamp`	Record time	Record time (the same)

The OpenTelemetry source envelope

All three outputs share the same envelope. message.type is log, metric, or trace, and message.record holds the signal-specific fields:

{
  "message": {
    "type": "log | metric | trace",
    "resource": { "attributes": { "service.name": "...", "...": "..." } },
    "scope": { "name": "...", "version": "...", "attributes": {} },
    "record": { }
  },
  "annotations": {
    "app": "...",
    "host": "..."
  },
  "timestamp": "..."
}

annotations.app is set from the service.name resource attribute, or k8s.container.name if that isn’t set.
annotations.host is set from the k8s.pod.name resource attribute, or host.name if that isn’t set.
timestamp is set from the record’s time:

Signal	`timestamp` source
Logs	`record.timeUnixNano`, falling back to `record.observedTimeUnixNano` when the time is missing or zero
Metrics	`record.dataPoint.timeUnixNano`
Traces	`record.startTimeUnixNano`

Logs

{
  "message": "GetSupportedCurrencies successful",
  "annotations": {
    "app": "currencyservice",
    "host": null,
    "level": "INFO"
  },
  "metadata": {
    "level": "INFO",
    "severity_text": "INFO",
    "severity_number": 9,
    "time": "2024-10-30T21:39:25.910765343Z",
    "observed_timestamp": "2024-10-30T21:39:25.910765343Z",
    "trace_id": "126da7e46ba0120bbfc51d3344345a7f",
    "span_id": "97b9833f952de53a",
    "flags": 1,
    "attributes": {},
    "resource": {
      "service.name": "currencyservice",
      "service.namespace": "opentelemetry-demo",
      "telemetry.sdk.language": "cpp",
      "telemetry.sdk.name": "opentelemetry",
      "telemetry.sdk.version": "1.13.0"
    },
    "scope": {
      "name": "currencyservice",
      "version": "1.13.0",
      "schema_url": "",
      "attributes": {}
    }
  },
  "timestamp": "2024-10-30T21:39:25.910765343Z"
}

{
  "message": {
    "type": "log",
    "resource": {
      "attributes": {
        "service.name": "checkout",
        "service.namespace": "shop",
        "k8s.namespace.name": "shop",
        "k8s.pod.name": "checkout-7d9f8c6b5-x2k4p",
        "k8s.container.name": "checkout"
      }
    },
    "scope": { "attributes": {} },
    "record": {
      "body": "Order 1234 submitted",
      "attributes": {
        "log.file.path": "/var/log/pods/shop_checkout-7d9f8c6b5-x2k4p/checkout/0.log",
        "log.iostream": "stdout"
      },
      "droppedAttributesCount": 0,
      "timeUnixNano": "1780449032085457504",
      "observedTimeUnixNano": "1780449032160116995"
    }
  },
  "annotations": {
    "app": "checkout",
    "host": "checkout-7d9f8c6b5-x2k4p"
  },
  "timestamp": "2026-06-03T01:10:32.085457504Z"
}

	Deprecated	OpenTelemetry
Log body	`message` (a string)	`message.record.body`
Severity	`metadata.severity_text`, `metadata.severity_number`, `metadata.level`	In `message.record` with OpenTelemetry JSON names, when the sender sets it
Level annotation	`annotations.level`	Not set
Log attributes	`metadata.attributes`	`message.record.attributes`
Resource attributes	`metadata.resource` (a flat map; no `attributes` wrapper)	`message.resource.attributes`
Scope	`metadata.scope`	`message.scope`
Trace context	`metadata.trace_id`, `metadata.span_id`, `metadata.flags`	In `message.record` with OpenTelemetry JSON names, when the sender sets it
Times	`metadata.time`, `metadata.observed_timestamp` (ISO 8601)	`message.record.timeUnixNano`, `message.record.observedTimeUnixNano` (nanosecond strings)

In the deprecated Logs source, metadata.resource holds resource attributes directly. In the deprecated Metrics and Traces sources, they’re nested under metadata.resource.attributes. In the OpenTelemetry source, they’re always at message.resource.attributes.

Metrics

{
  "message": {
    "name": "app_currency_counter_total",
    "kind": "incremental",
    "tags": {
      "service_name": "currencyservice",
      "service_namespace": "opentelemetry-demo",
      "telemetry_sdk_language": "cpp",
      "telemetry_sdk_name": "opentelemetry",
      "telemetry_sdk_version": "1.8.2",
      "currency_code": "USD"
    },
    "value": {
      "type": "counter",
      "value": 2,
      "name": "app_currency_counter",
      "description": "",
      "unit": "",
      "aggregation_temporality": 1,
      "is_monotonic": true,
      "flags": 0,
      "exemplars": [],
      "start_time_unix": "2023-04-18T17:43:59.995034076Z",
      "time_unix": "2023-04-18T17:44:00.995418807Z"
    }
  },
  "metadata": {
    "data_provider": "otlp",
    "original_type": "sum",
    "attributes": { "currency_code": "USD" },
    "resource": {
      "attributes": {
        "service.name": "currencyservice",
        "service.namespace": "opentelemetry-demo",
        "telemetry.sdk.language": "cpp",
        "telemetry.sdk.name": "opentelemetry",
        "telemetry.sdk.version": "1.8.2"
      },
      "dropped_attributes_count": 0
    },
    "scope": {
      "name": "app_currency",
      "version": "1.3.0",
      "attributes": {},
      "dropped_attributes_count": 0
    }
  },
  "timestamp": "2023-04-18T17:44:00.995418807Z"
}

{
  "message": {
    "type": "metric",
    "resource": {
      "attributes": {
        "service.name": "checkout",
        "service.namespace": "shop",
        "k8s.namespace.name": "shop",
        "k8s.pod.name": "checkout-7d9f8c6b5-x2k4p",
        "k8s.container.name": "checkout"
      }
    },
    "scope": {
      "name": "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/kubeletstatsreceiver",
      "version": "0.153.0",
      "attributes": {}
    },
    "record": {
      "metric": {
        "name": "k8s.pod.memory.major_page_faults",
        "description": "Pod memory major_page_faults",
        "unit": "1"
      },
      "dataPoint": {
        "type": "gauge",
        "valueType": "int",
        "value": "179",
        "attributes": {},
        "droppedAttributesCount": 0,
        "startTimeUnixNano": "1779221503000000000",
        "timeUnixNano": "1780449069447026056"
      }
    }
  },
  "annotations": {
    "app": "checkout",
    "host": "checkout-7d9f8c6b5-x2k4p"
  },
  "timestamp": "2026-06-03T01:11:09.447026056Z"
}

	Deprecated	OpenTelemetry
Event model	Mezmo metric: `message.name`, `kind`, `tags`, `value`	OpenTelemetry metric and data point: `message.record.metric`, `message.record.dataPoint`
Metric name	`message.name`, normalized (for example, counters get a `_total` suffix)	`message.record.metric.name`, the original OpenTelemetry name
Metric type	`message.kind` (`incremental` / `absolute`) and `message.value.type` (`counter`, `gauge`, …)	`message.record.dataPoint.type` (`gauge`, `sum`, …) and `valueType`; no `kind`
Value	Number in `message.value.value`	String in `message.record.dataPoint.value`
Description and unit	`message.value.description`, `message.value.unit`	`message.record.metric.description`, `message.record.metric.unit`
Labels	`message.tags`: resource and data point attributes merged, snake_case keys	Kept separate in `message.resource.attributes` and `message.record.dataPoint.attributes`, original dotted keys
Times	`message.value.start_time_unix`, `time_unix` (ISO 8601)	`message.record.dataPoint.startTimeUnixNano`, `timeUnixNano` (nanosecond strings)

Which fields appear in dataPoint depends on the metric type. The example above is a gauge. Sums, histograms, and summaries can carry other fields.

Traces

{
  "message": {
    "name": "featureflagservice.repo.query:featureflags",
    "kind": 3,
    "trace_id": "c4cea222120a566ceaf6334500ab0128",
    "span_id": "75e57f4609adff0e",
    "parent_span_id": "3e40b326a3290897",
    "trace_state": "",
    "start_timestamp": "2023-09-08T00:18:28.669047999Z",
    "end_timestamp": "2023-09-08T00:18:28.669820750Z",
    "status": { "code": 0, "message": null },
    "events": [],
    "links": [],
    "dropped_attributes_count": 0,
    "dropped_events_count": 0,
    "dropped_links_count": 0,
    "hostname": null
  },
  "metadata": {
    "level": "trace",
    "attributes": {
      "db.instance": "ffs",
      "db.type": "sql",
      "query_time_microseconds": 489,
      "total_time_microseconds": 546
    },
    "resource": {
      "attributes": {
        "service.name": "featureflagservice",
        "service.instance.id": "featureflagservice@d69d857131ac",
        "telemetry.sdk.language": "erlang",
        "telemetry.sdk.name": "opentelemetry",
        "telemetry.sdk.version": "1.2.1"
      },
      "dropped_attributes_count": 0,
      "schema_url": ""
    },
    "scope": {
      "name": "opentelemetry_ecto",
      "version": "1.0.0",
      "schema_url": "",
      "attributes": {}
    }
  },
  "timestamp": "2023-09-08T00:18:28.669047999Z"
}

{
  "message": {
    "type": "trace",
    "resource": {
      "attributes": {
        "service.name": "checkout",
        "service.namespace": "shop",
        "service.version": "2.4.0",
        "host.name": "checkout-host-01",
        "process.runtime.name": "nodejs"
      }
    },
    "scope": {
      "name": "@opentelemetry/instrumentation-http",
      "version": "0.218.0",
      "attributes": {}
    },
    "record": {
      "name": "POST",
      "kind": 2,
      "traceId": "bca4d8a2e7921b183605a8da1c3d3b9b",
      "spanId": "3a8bdb9cd7462418",
      "flags": 257,
      "startTimeUnixNano": "1780449350894000000",
      "endTimeUnixNano": "1780449350895065736",
      "status": { "code": 0 },
      "attributes": {
        "http.method": "POST",
        "http.route": "/orders",
        "http.status_code": "400",
        "net.peer.port": "36582"
      },
      "droppedAttributesCount": 0,
      "droppedEventsCount": 0,
      "droppedLinksCount": 0
    }
  },
  "annotations": {
    "app": "checkout",
    "host": "checkout-host-01"
  },
  "timestamp": "2026-06-03T01:15:50.894Z"
}

	Deprecated	OpenTelemetry
Span	`message`	`message.record`
IDs	`message.trace_id`, `span_id`, `parent_span_id`, `trace_state`	`message.record.traceId`, `spanId`, `parentSpanId` (camel case; empty IDs may be left out)
Times	`message.start_timestamp`, `end_timestamp` (ISO 8601)	`message.record.startTimeUnixNano`, `endTimeUnixNano` (nanosecond strings)
Span attributes	`metadata.attributes`, with typed values (for example, `"http.status_code": 200`)	`message.record.attributes`; values may be strings (for example, `"http.status_code": "400"`)
Resource and scope	`metadata.resource.attributes`, `metadata.scope`	`message.resource.attributes`, `message.scope`
Level	`metadata.level` is `"trace"`	Not set; use `message.type == "trace"`
Annotations	None	`app`, `host`
Dropped counts	`message.dropped_attributes_count`, etc.	`message.record.droppedAttributesCount`, etc.

Migrating from the deprecated sources

When you replace the deprecated sources with the OpenTelemetry source:

Add one OpenTelemetry source, and connect each downstream processor to its Logs, Metrics, or Traces output.
Update the field paths your processors use, following the tables above. For example:
- Logs: message becomes message.record.body
- Metrics: message.name becomes message.record.metric.name
- Traces: message.trace_id becomes message.record.traceId
- All signals: metadata.resource… becomes message.resource.attributes…
Convert values before doing math or numeric comparisons: metric values, *UnixNano times, and many attribute values arrive as strings.
Check for anything that relies on fields the new source doesn’t set, such as annotations.level on logs or metadata.level on traces.
If a destination expects Mezmo metric events, add a processor that remaps the OpenTelemetry metric fields to the Mezmo metric format first.

About Pipelines

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Other Topics

OpenTelemetry event shapes

At a glance

The OpenTelemetry source envelope

Logs

Metrics

Traces

Migrating from the deprecated sources

​At a glance

​The OpenTelemetry source envelope

​Logs

​Metrics

​Traces

​Migrating from the deprecated sources

At a glance

The OpenTelemetry source envelope

Logs

Metrics

Traces

Migrating from the deprecated sources