platform.initStart platform.initReport platform.invokeStart platform.requestComplete platform.invokeSummary platform.invokeReport platform.spinDownStart platform.spinDownReport platform.logsDropped Shared object types

System log event schema for Lambda Web Functions

Lambda writes the following system events to your Web Function's log group. Each event is a JSON object with the envelope fields described in Event envelope and a record object whose fields depend on the event type. The level of each event determines whether Lambda delivers it. For more information, see System logs.

Event type	Record object	Description
`platform.initStart`	`PlatformInitStart`	Environment initialization started.
`platform.initReport`	`PlatformInitReport`	Report of environment initialization, whether it succeeded or failed.
`platform.invokeStart`	`PlatformInvokeStart`	The environment started serving requests.
`platform.requestComplete`	`PlatformRequestComplete`	One HTTP request completed. Logged at DEBUG only.
`platform.invokeSummary`	`PlatformInvokeSummary`	Summary of the environment's activity, emitted about every 60 seconds.
`platform.invokeReport`	`PlatformInvokeReport`	Report of the environment's whole serving period, emitted when it stops serving.
`platform.spinDownStart`	`PlatformSpinDownStart`	Environment shutdown started.
`platform.spinDownReport`	`PlatformSpinDownReport`	Report of environment shutdown.
`platform.logsDropped`	`PlatformLogsDropped`	Log records were dropped because logs were produced faster than they could be delivered.

In the field lists on this page, a question mark (?) after a field name means that the field might not be present. Types that are not JSON types, such as InitType, Status, or InvokeSummaryMetrics, are defined in Shared object types, and each one links to its definition.

`platform.initStart`

The environment initialization phase started.

Level: INFO

The record object has the following fields:

functionName (String) – The name of the function.
revisionId (String) – The revision that the environment runs.
instanceId (String) – The identifier of the execution environment.
initializationType (InitType) – How Lambda initialized the environment.
runtimeVersion (String) – The runtime version that the environment runs.
runtimeVersionArn (String) – The Amazon Resource Name (ARN) of the runtime version.


{
  "timestamp": "2026-09-25T11:12:30.893Z",
  "level": "INFO",
  "type": "platform.initStart",
  "region": "us-east-1",
  "record": {
    "runtimeVersion": "nodejs24.x:nodejs.web24.v51",
    "runtimeVersionArn": "arn:aws:lambda:us-east-1::runtime/nodejs24.x/version/nodejs.web24.v51",
    "functionName": "my-web-app",
    "revisionId": "rev-fs0fq",
    "instanceId": "52754708-44f1-407a-a1fd-6d2a98175a45",
    "initializationType": "native-http"
  }
}

`platform.initReport`

Overall report of the initialization phase.

Level: INFO when status is success, WARN when failure.

The record object has the following fields:

status (Status) – The outcome of the initialization phase.
errorType? (String) – Present when status is failure. Values such as Runtime.ImportCodeError, Application.InitCodeError, and Runtime.InitTimeout.
initializationType (InitType) – How Lambda initialized the environment.
metrics (InitReportMetrics) – Metrics for the initialization phase.

Success example:


{
  "timestamp": "2026-09-25T11:12:31.143Z",
  "level": "INFO",
  "type": "platform.initReport",
  "region": "us-east-1",
  "record": {
    "status": "success",
    "initializationType": "native-http",
    "metrics": {
      "totalDurationMs": 304.000,
      "totalCpuTimeMs": 143.000,
      "maxMemoryUsageMb": 142
    }
  }
}

Failure example, where the handler module failed to load:


{
  "timestamp": "2026-09-25T11:16:04.164Z",
  "level": "WARN",
  "type": "platform.initReport",
  "region": "us-east-1",
  "record": {
    "status": "failure",
    "errorType": "Runtime.ImportCodeError",
    "initializationType": "native-http",
    "metrics": {
      "totalDurationMs": 320.000,
      "totalCpuTimeMs": 137.000,
      "maxMemoryUsageMb": 138
    }
  }
}

`platform.invokeStart`

The environment finished initializing and started serving requests. Lambda emits this event once per environment, not once per request, and only when initialization succeeded.

Level: INFO

The record object has the following fields:

functionName (String) – The name of the function.
revisionId (String) – The revision that the environment runs.
instanceId (String) – The identifier of the execution environment.


{
  "timestamp": "2026-09-25T11:12:31.144Z",
  "level": "INFO",
  "type": "platform.invokeStart",
  "region": "us-east-1",
  "record": {
    "functionName": "my-web-app",
    "revisionId": "rev-fs0fq",
    "instanceId": "52754708-44f1-407a-a1fd-6d2a98175a45"
  }
}

`platform.requestComplete`

One HTTP request finished, successfully or not.

Level: DEBUG, so Lambda delivers it only when systemLogLevel is DEBUG.

The record object has the following fields:

requestId (String) – The request ID.
endpointName (String) – The endpoint that served the request.
result (Integer) – The HTTP status code returned to the client.
errorType? (String) – Present when Lambda failed the request. Values such as Runtime.RequestTimeout and Platform.InvalidRequest.
metrics (RequestCompleteMetrics) – Metrics for the request.

Success example:


{
  "timestamp": "2026-09-25T11:12:31.154Z",
  "level": "DEBUG",
  "type": "platform.requestComplete",
  "region": "us-east-1",
  "record": {
    "requestId": "KXH25FBDZ33GP4TQ4ARAUYSTSA",
    "endpointName": "default",
    "result": 200,
    "metrics": {
      "durationMs": 4.484,
      "responseBytes": 40
    }
  }
}

Timeout example:


{
  "timestamp": "2026-09-25T11:12:34.926Z",
  "level": "DEBUG",
  "type": "platform.requestComplete",
  "region": "us-east-1",
  "record": {
    "requestId": "5SXHGVX2GD64ND6NQVEBAY235Q",
    "endpointName": "default",
    "result": 504,
    "errorType": "Runtime.RequestTimeout",
    "metrics": {
      "durationMs": 3001.229,
      "responseBytes": 0
    }
  }
}

`platform.invokeSummary`

Summarizes one window of about 60 seconds of an environment's activity. Lambda emits it for every live environment, including idle windows where requests is 0.

Level: INFO

The record object has the following fields:

startTime (String) – The start of the summary window (RFC 3339).
instanceId (String) – The identifier of the execution environment.
metrics (InvokeSummaryMetrics) – Metrics for the window.


{
  "timestamp": "2026-09-25T11:13:31.143Z",
  "level": "INFO",
  "type": "platform.invokeSummary",
  "region": "us-east-1",
  "record": {
    "startTime": "2026-09-25T11:12:31.144547426Z",
    "instanceId": "52754708-44f1-407a-a1fd-6d2a98175a45",
    "metrics": {
      "requests": 4,
      "concurrentRequests": 1,
      "cpuTimeMs": 420.000,
      "maxMemoryUsageMb": 154
    }
  }
}

`platform.invokeReport`

Overall report of the environment's serving period, from invokeStart until it stops serving. Lambda emits it once per environment, at shutdown.

Level: INFO when status is success, WARN when failure.

The record object has the following fields:

status (Status) – The outcome of the serving period.
errorType? (String) – Present when status is failure. Values such as Runtime.Exit, Runtime.ExitError, and Runtime.OutOfMemory.
instanceId (String) – The identifier of the execution environment.
metrics (InvokeReportMetrics) – Metrics for the serving period.

A request timeout does not fail the serving period. The status stays success.

Success example:


{
  "timestamp": "2026-09-25T11:19:11.858Z",
  "level": "INFO",
  "type": "platform.invokeReport",
  "region": "us-east-1",
  "record": {
    "status": "success",
    "instanceId": "52754708-44f1-407a-a1fd-6d2a98175a45",
    "metrics": {
      "totalCpuTimeMs": 973.000,
      "totalDurationMs": 400723.000,
      "totalRequests": 4,
      "concurrentRequests": 1,
      "maxMemoryUsageMb": 157
    }
  }
}

Failure example:


{
  "timestamp": "2026-09-25T11:19:11.858Z",
  "level": "WARN",
  "type": "platform.invokeReport",
  "region": "us-east-1",
  "record": {
    "status": "failure",
    "errorType": "Runtime.OutOfMemory",
    "instanceId": "52754708-44f1-407a-a1fd-6d2a98175a45",
    "metrics": {
      "totalCpuTimeMs": 973.000,
      "totalDurationMs": 400723.000,
      "totalRequests": 4,
      "concurrentRequests": 1,
      "maxMemoryUsageMb": 512
    }
  }
}

`platform.spinDownStart`

Environment shutdown started.

Level: INFO

The record object has the following fields:

functionName (String) – The name of the function.
revisionId (String) – The revision that the environment runs.
instanceId (String) – The identifier of the execution environment.


{
  "timestamp": "2026-09-25T11:19:11.858Z",
  "level": "INFO",
  "type": "platform.spinDownStart",
  "region": "us-east-1",
  "record": {
    "functionName": "my-web-app",
    "revisionId": "rev-fs0fq",
    "instanceId": "52754708-44f1-407a-a1fd-6d2a98175a45"
  }
}

`platform.spinDownReport`

Overall report of the shutdown.

Lambda sends SIGTERM to your application and waits up to 1 second for it to exit. If the application is still running, Lambda stops it with SIGKILL and reports a failure with the error type Runtime.SpinDownTimeout.

Level: INFO when status is success, WARN when failure.

The record object has the following fields:

status (Status) – The outcome of the shutdown phase.
errorType? (String) – Present when status is failure. Values such as Runtime.SpinDownTimeout and Runtime.ExitError.
metrics (SpinDownReportMetrics) – Metrics for the shutdown phase.

Success example:


{
  "timestamp": "2026-09-25T11:19:11.879Z",
  "level": "INFO",
  "type": "platform.spinDownReport",
  "region": "us-east-1",
  "record": {
    "status": "success",
    "metrics": {
      "totalDurationMs": 21.000,
      "totalCpuTimeMs": 8.000,
      "maxMemoryUsageMb": 157
    }
  }
}

Failure example:


{
  "timestamp": "2026-09-25T11:19:12.879Z",
  "level": "WARN",
  "type": "platform.spinDownReport",
  "region": "us-east-1",
  "record": {
    "status": "failure",
    "errorType": "Runtime.SpinDownTimeout",
    "metrics": {
      "totalDurationMs": 1021.000,
      "totalCpuTimeMs": 8.000,
      "maxMemoryUsageMb": 157
    }
  }
}

`platform.logsDropped`

Log records were dropped because logs were produced faster than they could be delivered.

Level: WARN

The record object has the following fields:

reason (String) – Why the records were dropped.
droppedRecords (Integer) – Records dropped since the last record that was delivered.
droppedBytes (Integer) – Bytes dropped since the last record that was delivered.

Both counts accumulate across consecutive drops and reset to 0 after a record is delivered.


{
  "timestamp": "2026-09-25T11:20:00.000Z",
  "level": "WARN",
  "type": "platform.logsDropped",
  "region": "us-east-1",
  "record": {
    "reason": "Some logs were dropped because the downstream consumer is slower than the logs production rate",
    "droppedRecords": 120,
    "droppedBytes": 48000
  }
}

Shared object types

The following types appear in the field lists of the events on this page.

Event envelope

Every system event has the following envelope fields:

timestamp (String) – RFC 3339 in UTC.
level (Level) – The level of the event.
type (String) – The event type (platform.*).
region (String) – The Region where the execution environment ran.
record (Object) – The event-specific fields.

`InitType`

String enum that describes how Lambda initialized the environment. Web Functions always use native-http.

`Level`

String enum for the level of a system event: DEBUG, INFO, or WARN. System events are never ERROR or FATAL. Report events are INFO when status is success and WARN when it is failure.

`Status`

String enum that describes the outcome of a phase: success or failure. When it is failure, the record also contains errorType.

`InitReportMetrics`

totalDurationMs (Double) – Wall-clock time of the initialization phase.
totalCpuTimeMs (Double) – CPU time consumed during initialization.
maxMemoryUsageMb (Integer) – Peak memory of the environment, in MiB.

`RequestCompleteMetrics`

durationMs (Double) – Wall-clock time of the request.
responseBytes (Integer) – Response body bytes sent.

`InvokeSummaryMetrics`

requests (Integer) – Requests completed in the window.
concurrentRequests (Integer) – Maximum concurrent requests in the window.
cpuTimeMs (Double) – CPU time consumed in the window.
maxMemoryUsageMb (Integer) – Peak memory of the environment, in MiB.

`InvokeReportMetrics`

totalCpuTimeMs (Double) – CPU time over the serving period.
totalDurationMs (Double) – Wall-clock time from invokeStart until the environment stopped serving.
totalRequests (Integer) – Total requests served.
concurrentRequests (Integer) – Maximum concurrent requests over the period.
maxMemoryUsageMb (Integer) – Peak memory of the environment, in MiB.

`SpinDownReportMetrics`

totalDurationMs (Double) – Wall-clock time of the shutdown phase.
totalCpuTimeMs (Double) – CPU time consumed during shutdown.
maxMemoryUsageMb (Integer) – Peak memory of the environment, in MiB.

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