SnapStartEnabled.py

"""
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
SPDX-License-Identifier: MIT-0
"""

from cfnlint.rules import CloudFormationLintRule, RuleMatch


class SnapStartEnabled(CloudFormationLintRule):
    """Check if the SnapStart is enabled for certain java runtimes"""

    id = "I2530"
    shortdesc = "Validate that SnapStart is configured for >= Java11 runtimes"
    description = (
        "SnapStart is a no-cost feature that can increase performance up to 10x. "
        "Enable SnapStart for Java 11 and greater runtimes"
    )
    source_url = "https://docs.aws.amazon.com/lambda/latest/dg/snapstart.html"
    tags = ["resources", "lambda"]

    def __init__(self):
        super().__init__()
        self.resource_property_types.append("AWS::Lambda::Function")

    def validate(self, runtime, path, region, regions):
        if not isinstance(runtime, str):
            return []

        if region not in regions:
            return []

        if not (runtime.startswith("java")) or runtime in ["java8.al2", "java8"]:
            return []

        return [
            RuleMatch(
                path,
                f"When using {runtime} configure SnapStart",
                rule=self,
            )
        ]