Semantic Conventions for FaaS Metrics
Status: Experimental
This document defines how to describe an instance of a function that runs without provisioning or managing of servers (also known as serverless functions or Function as a Service (FaaS)) with metrics.
The conventions described in this section are FaaS (function as a service) specific. When FaaS operations occur, metric events about those operations will be generated and reported to provide insights into the operations. By adding FaaS attributes to metric events it allows for finely tuned filtering.
Metric Instruments
The following metric instruments describe FaaS operations.
FaaS Instance
The following metrics are recorded by the FaaS instance.
Metric: faas.invoke_duration
This metric is recommended.
This metric SHOULD be specified with
ExplicitBucketBoundaries
of [ 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 ].
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.invoke_duration | Histogram | s | Measures the duration of the function’s logic execution |  |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.init_duration
This metric is recommended.
This metric SHOULD be specified with
ExplicitBucketBoundaries
of [ 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 ].
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.init_duration | Histogram | s | Measures the duration of the function’s initialization, such as a cold start | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.coldstarts
This metric is recommended.
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.coldstarts | Counter | {coldstart} | Number of invocation cold starts | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.errors
This metric is recommended.
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.errors | Counter | {error} | Number of invocation errors | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.invocations
This metric is recommended.
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.invocations | Counter | {invocation} | Number of successful invocations | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.timeouts
This metric is recommended.
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.timeouts | Counter | {timeout} | Number of invocation timeouts | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.mem_usage
This metric is recommended.
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.mem_usage | Histogram | By | Distribution of max memory usage per invocation | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.cpu_usage
This metric is recommended.
This metric SHOULD be specified with
ExplicitBucketBoundaries
of [ 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 ].
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.cpu_usage | Histogram | s | Distribution of CPU usage per invocation | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
Metric: faas.net_io
This metric is recommended.
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
faas.net_io | Histogram | By | Distribution of net I/O usage per invocation | |
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
faas.trigger | string | Type of the trigger which caused this function invocation. | datasource; http; pubsub | Recommended | |
faas.trigger has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
|---|---|---|
datasource | A response to some data source operation such as a database or filesystem read/write | |
http | To provide an answer to an inbound HTTP request | |
other | If none of the others apply | |
pubsub | A function is set to be executed when messages are sent to a messaging system | |
timer | A function is scheduled to be executed regularly | |
References
Metric References
Below are links to documentation regarding metrics that are available with different FaaS providers. This list is not exhaustive.
- AWS Lambda Metrics
- AWS Lambda Insight Metrics
- Azure Functions Metrics
- Google CloudFunctions Metrics
- OpenFaas Metrics
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