Bug: start-api error when using Lambda function Alias

[rangerthegood]

Description:

When using an openapi definition for a SpecRestApi where the x-amazon-apigateway-integration points to a Lambda function Alias, you will recieve the error 'Error: Template does not have any APIs connected to Lambda functions' when trying to run 'sam local start-api'.

Steps to reproduce:

Here is a simple CDK stack which was used to re-produce this issue.

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as apigateway from 'aws-cdk-lib/aws-apigateway';
import * as path from 'path';


export class SpecRestApiStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // Define the Lambda function with inline code
    const helloWorldFunction = new lambda.Function(this, 'HelloWorldFunctionSpec', {
      runtime: lambda.Runtime.NODEJS_18_X,
      handler: 'index.handler',
      code: lambda.Code.fromAsset(path.join(__dirname, 'lambda')),
    });

    // Create a Lambda alias
    const alias = new lambda.Alias(this, 'HelloWorldAliasSpec', {
      aliasName: 'prod',
      version: helloWorldFunction.currentVersion,
    });

    // Define the API Gateway using SpecRestApi
    const api = new apigateway.SpecRestApi(this, 'SpecRestApi', {
      apiDefinition: apigateway.ApiDefinition.fromInline({
        openapi: '3.0.1',
        info: {
          title: 'SpecRestApi',
          version: '1.0'
        },
        paths: {
          '/test': {
            get: {
              'x-amazon-apigateway-integration': {
                uri: `arn:aws:apigateway:${cdk.Aws.REGION}:lambda:path/2015-03-31/functions/${alias.functionArn}/invocations`,
                httpMethod: 'POST',
                type: 'aws_proxy'
              },
              responses: {
                200: {
                  description: '200 response',
                  content: {
                    'application/json': {
                      schema: {
                        type: 'string'
                      }
                    }
                  }
                }
              }
            }
          }
        }
      })
    });

    // Grant permissions for the API Gateway to invoke the Lambda alias
    alias.grantInvoke(new cdk.aws_iam.ServicePrincipal('apigateway.amazonaws.com'));
  }
}

Build this stack using cdk synth, and then use sam build with the resulting template.

Then run sam local start-api

Observed result:

sam local start-ap --debug
2025-01-12 10:21:56 Attaching import module proxy for analyzing dynamic imports
2025-01-12 10:21:56,618 | No config file found in this directory.
2025-01-12 10:21:56,620 | OSError occurred while reading TOML file: [Errno 2] No such file or directory: '/home/ranger/projects/sam-local/.aws-sam/build/samconfig.toml'
2025-01-12 10:21:56,620 | Config file location: /home/ranger/projects/sam-local/.aws-sam/build/samconfig.toml
2025-01-12 10:21:56,621 | Config file '/home/ranger/projects/sam-local/.aws-sam/build/samconfig.toml' does not exist
2025-01-12 10:21:56,632 | OSError occurred while reading TOML file: [Errno 2] No such file or directory: '/home/ranger/projects/sam-local/.aws-sam/build/samconfig.toml'
2025-01-12 10:21:56,633 | Using config file: samconfig.toml, config environment: default
2025-01-12 10:21:56,633 | Expand command line arguments to:
2025-01-12 10:21:56,634 | --template_file=/home/ranger/projects/sam-local/.aws-sam/build/template.yaml --host=127.0.0.1 --port=3000 --static_dir=public
--layer_cache_basedir=/home/ranger/.aws-sam/layers-pkg --container_host=localhost --container_host_interface=127.0.0.1
2025-01-12 10:21:56,655 | local start-api command is called
2025-01-12 10:21:58,719 | No current session found, using default AWS::AccountId
2025-01-12 10:21:58,730 | Collected default values for parameters: {'BootstrapVersion': '/cdk-bootstrap/hnb659fds/version'}
2025-01-12 10:21:58,743 | CDK Path for resource HelloWorldFunctionSpecServiceRoleF796918C is ['Spec', 'HelloWorldFunctionSpec', 'ServiceRole', 'Resource']
2025-01-12 10:21:58,744 | Sam customer defined id is more priority than other IDs. Customer defined id for resource HelloWorldFunctionSpec17441592 is HelloWorldFunctionSpec
2025-01-12 10:21:58,744 | CDK Path for resource HelloWorldFunctionSpecCurrentVersion972EE62B1134dc36c01a9834549bf5ef22ce6e36 is ['Spec', 'HelloWorldFunctionSpec',
'CurrentVersion', 'Resource']
2025-01-12 10:21:58,745 | CDK Path for resource HelloWorldAliasSpec31D71541 is ['Spec', 'HelloWorldAliasSpec', 'Resource']
2025-01-12 10:21:58,745 | CDK Path for resource HelloWorldAliasSpecInvokeFcyXBRX02EWa52GlFECQiCzDt0fdRUDi4mo4foC5aUCDF9A5D5 is ['Spec', 'HelloWorldAliasSpec',
'InvokeFcyXBRX02EWa52GlF+ECQiCzDt0fdRUDi4mo4foC5aU=']
2025-01-12 10:21:58,746 | CDK Path for resource SpecRestApiB69335EA is ['Spec', 'SpecRestApi', 'Resource']
2025-01-12 10:21:58,746 | CDK Path for resource SpecRestApiDeployment33C0029Ab4278f349fd9e00e29327dd3f4381ff0 is ['Spec', 'SpecRestApi', 'Deployment', 'Resource']
2025-01-12 10:21:58,746 | CDK Path for resource SpecRestApiDeploymentStageprod6BB55B6A is ['Spec', 'SpecRestApi', 'DeploymentStage.prod', 'Resource']
2025-01-12 10:21:58,747 | CDK Path for resource CDKMetadata is ['Spec', 'CDKMetadata', 'Default']
2025-01-12 10:21:58,748 | Unable to resolve property FunctionVersion: OrderedDict([('Fn::GetAtt',
['HelloWorldFunctionSpecCurrentVersion972EE62B1134dc36c01a9834549bf5ef22ce6e36', 'Version'])]). Leaving as is.
2025-01-12 10:21:58,748 | 0 stacks found in the template
2025-01-12 10:21:58,749 | Collected default values for parameters: {'BootstrapVersion': '/cdk-bootstrap/hnb659fds/version'}
2025-01-12 10:21:58,760 | CDK Path for resource HelloWorldFunctionSpecServiceRoleF796918C is ['Spec', 'HelloWorldFunctionSpec', 'ServiceRole', 'Resource']
2025-01-12 10:21:58,760 | Sam customer defined id is more priority than other IDs. Customer defined id for resource HelloWorldFunctionSpec17441592 is HelloWorldFunctionSpec
2025-01-12 10:21:58,761 | CDK Path for resource HelloWorldFunctionSpecCurrentVersion972EE62B1134dc36c01a9834549bf5ef22ce6e36 is ['Spec', 'HelloWorldFunctionSpec',
'CurrentVersion', 'Resource']
2025-01-12 10:21:58,761 | CDK Path for resource HelloWorldAliasSpec31D71541 is ['Spec', 'HelloWorldAliasSpec', 'Resource']
2025-01-12 10:21:58,762 | CDK Path for resource HelloWorldAliasSpecInvokeFcyXBRX02EWa52GlFECQiCzDt0fdRUDi4mo4foC5aUCDF9A5D5 is ['Spec', 'HelloWorldAliasSpec',
'InvokeFcyXBRX02EWa52GlF+ECQiCzDt0fdRUDi4mo4foC5aU=']
2025-01-12 10:21:58,762 | CDK Path for resource SpecRestApiB69335EA is ['Spec', 'SpecRestApi', 'Resource']
2025-01-12 10:21:58,762 | CDK Path for resource SpecRestApiDeployment33C0029Ab4278f349fd9e00e29327dd3f4381ff0 is ['Spec', 'SpecRestApi', 'Deployment', 'Resource']
2025-01-12 10:21:58,763 | CDK Path for resource SpecRestApiDeploymentStageprod6BB55B6A is ['Spec', 'SpecRestApi', 'DeploymentStage.prod', 'Resource']
2025-01-12 10:21:58,763 | CDK Path for resource CDKMetadata is ['Spec', 'CDKMetadata', 'Default']
2025-01-12 10:21:58,764 | Unable to resolve property FunctionVersion: OrderedDict([('Fn::GetAtt',
['HelloWorldFunctionSpecCurrentVersion972EE62B1134dc36c01a9834549bf5ef22ce6e36', 'Version'])]). Leaving as is.
2025-01-12 10:21:58,765 | 9 resources found in the stack
2025-01-12 10:21:58,765 | Found Lambda function with name='HelloWorldFunctionSpec17441592' and CodeUri='HelloWorldFunctionSpec17441592'
2025-01-12 10:21:58,765 | --base-dir is not presented, adjusting uri HelloWorldFunctionSpec17441592 relative to /home/ranger/projects/sam-local/.aws-sam/build/template.yaml
2025-01-12 10:21:58,767 | Detected Inline Swagger definition
2025-01-12 10:21:58,768 | Parsing Swagger document using 3.0 specification
2025-01-12 10:21:58,768 | Found '0' authorizers in resource 'SpecRestApiB69335EA'
2025-01-12 10:21:58,769 | Extracted Function ARN: HelloWorldAliasSpec31D71541
2025-01-12 10:21:58,769 | No Lambda function ARN defined for integration containing ARN HelloWorldAliasSpec31D71541
2025-01-12 10:21:58,769 | Lambda function integration not found in Swagger document at path='/test' method='get'
2025-01-12 10:21:58,770 | Found '0' APIs in resource 'SpecRestApiB69335EA'
2025-01-12 10:21:58,770 | 0 APIs found in the template
2025-01-12 10:21:58,772 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
2025-01-12 10:21:58,776 | Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
2025-01-12 10:21:58,777 | Unable to find Click Context for getting session_id.

Expected result:

I would expect that the sam cli start-api be able to find my Lambda function which is referrenced via an Alias.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

{
  "version": "1.127.0",
  "system": {
    "python": "3.11.10",
    "os": "Linux-6.2.0-33-generic-x86_64-with-glibc2.35"
  },
  "additional_dependencies": {
    "docker_engine": "24.0.5",
    "aws_cdk": "Not available",
    "terraform": "Not available"
  },
  "available_beta_feature_env_vars": [
    "SAM_CLI_BETA_FEATURES",
    "SAM_CLI_BETA_BUILD_PERFORMANCE",
    "SAM_CLI_BETA_TERRAFORM_SUPPORT",
    "SAM_CLI_BETA_RUST_CARGO_LAMBDA"
  ]
}