> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mezmo.com/llms.txt
> Use this file to discover all available pages before exploring further.
# OpenTelemetry event shapes
> How log, metric, and trace events from the OpenTelemetry source differ from the deprecated per-signal OpenTelemetry sources
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:
```json theme={null}
{
"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
```json Deprecated (OpenTelemetry Logs) theme={null}
{
"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"
}
```
```json OpenTelemetry (Logs output) theme={null}
{
"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
```json Deprecated (OpenTelemetry Metrics) theme={null}
{
"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"
}
```
```json OpenTelemetry (Metrics output) theme={null}
{
"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
```json Deprecated (OpenTelemetry Traces) theme={null}
{
"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"
}
```
```json OpenTelemetry (Traces output) theme={null}
{
"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:
1. Add one **OpenTelemetry** source, and connect each downstream processor to its **Logs**, **Metrics**, or **Traces** output.
2. 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…`
3. Convert values before doing math or numeric comparisons: metric values, `*UnixNano` times, and many attribute values arrive as strings.
4. Check for anything that relies on fields the new source doesn't set, such as `annotations.level` on logs or `metadata.level` on traces.
5. If a destination expects Mezmo metric events, add a processor that remaps the OpenTelemetry metric fields to the Mezmo metric format first.