AWS Serverless Application Model
Developer Guide

sam local start-lambda

Enables you to programmatically invoke your Lambda function locally by using the AWS CLI or SDKs. This command starts a local endpoint that emulates AWS Lambda. You can run your automated tests against this local Lambda endpoint. When you send an invoke to this endpoint using the AWS CLI or SDK, it locally executes the Lambda function that's specified in the request.

Usage:

sam local start-lambda [OPTIONS]

Examples:

SETUP ------ Start the local Lambda endpoint by running this command in the directory that contains your AWS SAM template. $ sam local start-lambda USING AWS CLI ------------- Then, you can invoke your Lambda function locally using the AWS CLI $ aws lambda invoke --function-name "HelloWorldFunction" --endpoint-url "http://127.0.0.1:3001" --no-verify-ssl out.txt USING AWS SDK ------------- You can also use the AWS SDK in your automated tests to invoke your functions programatically. Here is a Python example: self.lambda_client = boto3.client('lambda', endpoint_url="http://127.0.0.1:3001", use_ssl=False, verify=False, config=Config(signature_version=UNSIGNED, read_timeout=0, retries={'max_attempts': 0})) self.lambda_client.invoke(FunctionName="HelloWorldFunction")

Options:

Option Description
--host TEXT The local hostname or IP address to bind to (default: '127.0.0.1').
-p, --port INTEGER The local port number to listen on (default: '3001').
-t, --template PATH The AWS SAM template file [default: template.[yaml|yml]].
-n, --env-vars PATH The JSON file that contains values for the Lambda function's environment variables.
--parameter-overrides Optional. A string that contains AWS CloudFormation parameter overrides encoded as key-value pairs. Use the same format as the AWS CLI—for example, 'ParameterKey=KeyPairName, ParameterValue=MyKey ParameterKey=InstanceType,ParameterValue=t1.micro'.
-d, --debug-port TEXT When specified, starts the Lambda function container in debug mode, and exposes this port on the local host.
--debugger-path TEXT The host path to a debugger to be mounted into the Lambda container.
--debug-args TEXT Additional arguments to be passed to the debugger.
-v, --docker-volume-basedir TEXT The location of the base directory where the AWS SAM file exists. If Docker is running on a remote machine, you must mount the path where the AWS SAM file exists on the Docker machine, and modify this value to match the remote machine.
--docker-network TEXT The name or ID of an existing Docker network that Lambda Docker containers should connect to, along with the default bridge network. If this is specified, the Lambda containers only connect to the default bridge Docker network.
-l, --log-file TEXT The log file to send runtime logs to.
--layer-cache-basedir DIRECTORY Specifies the location basedir where the layers your template uses are downloaded to.
--skip-pull-image Specifies whether the CLI should skip pulling down the latest Docker image for the Lambda runtime.
--force-image-build Specify whether the CLI should rebuild the image used for invoking functions with layers.
--profile TEXT The AWS credentials profile to use.
--region TEXT Sets the AWS Region of the service (for example, us-east-1).
--debug Turns on debug logging.
--help Shows this message and exits.