Module aws_lambda_powertools.metrics.metric

Context manager to simplify creation of a single metric

Example

Creates cold start metric with function_version as dimension

from aws_lambda_powertools import single_metric
from aws_lambda_powertools.metrics import MetricUnit
from aws_lambda_powertools.metrics import MetricResolution

with single_metric(name="ColdStart", unit=MetricUnit.Count, value=1, resolution=MetricResolution.Standard, namespace="ServerlessAirline") as metric:
    metric.add_dimension(name="function_version", value="47")

Same as above but set namespace using environment variable

$ export POWERTOOLS_METRICS_NAMESPACE="ServerlessAirline"

from aws_lambda_powertools import single_metric
from aws_lambda_powertools.metrics import MetricUnit
from aws_lambda_powertools.metrics import MetricResolution

with single_metric(name="ColdStart", unit=MetricUnit.Count, value=1, resolution=MetricResolution.Standard) as metric:
    metric.add_dimension(name="function_version", value="47")

Parameters

name : str

Metric name

unit : MetricUnit

aws_lambda_powertools.helper.models.MetricUnit

resolution : MetricResolution

aws_lambda_powertools.helper.models.MetricResolution

value : float

Metric value

namespace : str

Namespace for metrics

default_dimensions : Dict[str, str], optional

Metric dimensions as key=value that will always be present

Yields

SingleMetric

SingleMetric class instance

Raises

MetricUnitError

When metric metric isn't supported by CloudWatch

MetricResolutionError

When metric resolution isn't supported by CloudWatch

MetricValueError

When metric value isn't a number

SchemaValidationError

When metric object fails EMF schema validation

SingleMetric creates an EMF object with a single metric.

EMF specification doesn't allow metrics with different dimensions. SingleMetric overrides MetricManager's add_metric method to do just that.

Use single_metric() when you need to create metrics with different dimensions, otherwise Metrics is a more cost effective option

Environment Variables

POWERTOOLS_METRICS_NAMESPACE : str metric namespace

Example

Creates cold start metric with function_version as dimension

import json
from aws_lambda_powertools.metrics import single_metric, MetricUnit, MetricResolution
metric = single_metric(namespace="ServerlessAirline")

metric.add_metric(name="ColdStart", unit=MetricUnit.Count, value=1, resolution=MetricResolution.Standard)
metric.add_dimension(name="function_version", value=47)

print(json.dumps(metric.serialize_metric_set(), indent=4))

Parameters

MetricManager : MetricManager

Inherits from MetricManager

class SingleMetric(MetricManager):
    """SingleMetric creates an EMF object with a single metric.

    EMF specification doesn't allow metrics with different dimensions.
    SingleMetric overrides MetricManager's add_metric method to do just that.

    Use `single_metric` when you need to create metrics with different dimensions,
    otherwise `aws_lambda_powertools.metrics.metrics.Metrics` is
    a more cost effective option

    Environment variables
    ---------------------
    POWERTOOLS_METRICS_NAMESPACE : str
        metric namespace

    Example
    -------
    **Creates cold start metric with function_version as dimension**

        import json
        from aws_lambda_powertools.metrics import single_metric, MetricUnit, MetricResolution
        metric = single_metric(namespace="ServerlessAirline")

        metric.add_metric(name="ColdStart", unit=MetricUnit.Count, value=1, resolution=MetricResolution.Standard)
        metric.add_dimension(name="function_version", value=47)

        print(json.dumps(metric.serialize_metric_set(), indent=4))

    Parameters
    ----------
    MetricManager : MetricManager
        Inherits from `aws_lambda_powertools.metrics.base.MetricManager`
    """

    def add_metric(
        self,
        name: str,
        unit: MetricUnit | str,
        value: float,
        resolution: MetricResolution | int = 60,
    ) -> None:
        """Method to prevent more than one metric being created

        Parameters
        ----------
        name : str
            Metric name (e.g. BookingConfirmation)
        unit : MetricUnit
            Metric unit (e.g. "Seconds", MetricUnit.Seconds)
        value : float
            Metric value
        resolution : MetricResolution
            Metric resolution (e.g. 60, MetricResolution.Standard)
        """
        if len(self.metric_set) > 0:
            logger.debug(f"Metric {name} already set, skipping...")
            return
        return super().add_metric(name, unit, value, resolution)