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.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.invoke_duration |
Histogram |
ms |
Measures the duration of the function’s logic execution |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.init_duration
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.init_duration |
Histogram |
ms |
Measures the duration of the function’s initialization, such as a cold start |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.coldstarts
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.coldstarts |
Counter |
{coldstart} |
Number of invocation cold starts |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.errors
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.errors |
Counter |
{error} |
Number of invocation errors |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.invocations
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.invocations |
Counter |
{invocation} |
Number of successful invocations |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.timeouts
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.timeouts |
Counter |
{timeout} |
Number of invocation timeouts |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.mem_usage
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.mem_usage |
Histogram |
By |
Distribution of max memory usage per invocation |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.cpu_usage
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.cpu_usage |
Histogram |
ms |
Distribution of CPU usage per invocation |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
Metric: faas.net_io
This metric is recommended.
| Name |
Instrument Type |
Unit (UCUM) |
Description |
faas.net_io |
Histogram |
By |
Distribution of net I/O usage per invocation |
| Attribute |
Type |
Description |
Examples |
Requirement Level |
faas.trigger |
string |
Type of the trigger which caused this function invocation. |
datasource |
Recommended |
faas.trigger MUST be one of the following:
| Value |
Description |
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 |
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 |
other |
If none of the others apply |
References
Metric References
Below are links to documentation regarding metrics that are available with different
FaaS providers. This list is not exhaustive.