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Using AWS Lambda with the AWS Command Line Interface

You can use the AWS Command Line Interface to manage functions and other AWS Lambda resources. The AWS CLI uses the AWS SDK for Python (Boto) to interact with the Lambda API. You can use it to learn about the API, and apply that knowledge in building applications that use Lambda with the AWS SDK.

In this tutorial, you manage and invoke Lambda functions with the AWS CLI.

Prerequisites

This tutorial assumes that you have some knowledge of basic Lambda operations and the Lambda console. If you haven't already, follow the instructions in Getting Started to create your first Lambda function.

To follow the procedures in this guide, you will need a command line terminal or shell to run commands. Commands are shown in listings preceded by a prompt symbol ($) and the name of the current directory, when appropriate:

~/lambda-project$ this is a command
this is output

For long commands, an escape character (\) is used to split a command over multiple lines.

On Linux and macOS, use your preferred shell and package manager. On Windows 10, you can install the Windows Subsystem for Linux to get a Windows-integrated version of Ubuntu and Bash.

Create the Execution Role

Create the execution role that gives your function permission to access AWS resources.

To create an execution role

  1. Open the roles page in the IAM console.

  2. Choose Create role.

  3. Create a role with the following properties.

    • Trusted entity – AWS Lambda.
    • Permissions – AWSLambdaBasicExecutionRole.
    • Role name – lambda-cli-role.

The AWSLambdaBasicExecutionRole policy has the permissions that the function needs to write logs to CloudWatch Logs.

Create the Function

The following example code receives an event as input and logs some of the incoming event data to CloudWatch Logs.

Example index.js

console.log('Loading function');

exports.handler = function(event, context, callback) {
    console.log('value1 =', event.key1);
    console.log('value2 =', event.key2);
    console.log('value3 =', event.key3);
    callback(null, "Success");
};

To create the function

  1. Copy the sample code into a file named index.js.

  2. Create a deployment package.

    $ zip function.zip index.js

  3. Create a Lambda function with the create-function command.

    $ aws lambda create-function --function-name helloworld \
--zip-file fileb://function.zip --handler index.handler --runtime nodejs8.10 \
--role role-arn
{
    "FunctionName": "helloworld",
    "CodeSize": 351,
    "MemorySize": 128,
    "FunctionArn": "function-arn",
    "Handler": "index.handler",
    "Role": "arn:aws:iam::account-id:role/LambdaExecRole",
    "Timeout": 3,
    "LastModified": "2015-04-07T22:02:58.854+0000",
    "Runtime": "nodejs8.10",
    "Description": ""
}

Invoke your Lambda function using the invoke command.

$ aws lambda invoke --function-name helloworld --log-type Tail \
--payload '{"key1":"value1", "key2":"value2", "key3":"value3"}' \
outputfile.txt
{
     "LogResult": "base64-encoded-log",
     "StatusCode": 200 
}

By specifying the --log-type parameter, the command also requests the tail end of the log produced by the function. The log data in the response is base64-encoded. Use the base64 program to decode the log.

$ echo base64-encoded-log | base64 --decode
START RequestId: 16d25499-d89f-11e4-9e64-5d70fce44801
2015-04-01T18:44:12.323Z    16d25499-d89f-11e4-9e64-5d70fce44801    value1 = value1
2015-04-01T18:44:12.323Z    16d25499-d89f-11e4-9e64-5d70fce44801    value2 = value2
2015-04-01T18:44:12.323Z    16d25499-d89f-11e4-9e64-5d70fce44801    value3 = value3
2015-04-01T18:44:12.323Z    16d25499-d89f-11e4-9e64-5d70fce44801    result: "value1"
END RequestId: 16d25499-d89f-11e4-9e64-5d70fce44801
REPORT RequestId: 16d25499-d89f-11e4-9e64-5d70fce44801       
Duration: 13.35 ms      Billed Duration: 100 ms   Memory Size: 128 MB  
Max Memory Used: 9 MB

Because you invoked the function using the default invocation type (RequestResponse), the connection stays open until execution completes. Lambda writes the response to the output file.

List the Lambda Functions in Your Account

Execute the following AWS CLI list-functions command to retrieve a list of functions that you have created.

$ aws lambda list-functions --max-items 10
{
    "Functions": [
        {
            "FunctionName": "helloworld",
            "MemorySize": 128,
            "CodeSize": 412,
            "FunctionArn": "arn:aws:lambda:us-east-1:account-id:function:ProcessKinesisRecords",
            "Handler": "ProcessKinesisRecords.handler",
            "Role": "arn:aws:iam::account-id:role/LambdaExecRole",
            "Timeout": 3,
            "LastModified": "2015-02-22T21:03:01.172+0000",
            "Runtime": "nodejs6.10",
            "Description": ""
        },
        {
            "FunctionName": "ProcessKinesisRecords",
            "MemorySize": 128,
            "CodeSize": 412,
            "FunctionArn": "arn:aws:lambda:us-east-1:account-id:function:ProcessKinesisRecords",
            "Handler": "ProcessKinesisRecords.handler",
            "Role": "arn:aws:iam::account-id:role/lambda-execute-test-kinesis",
            "Timeout": 3,
            "LastModified": "2015-02-22T21:03:01.172+0000",
            "Runtime": "nodejs6.10",
            "Description": ""
        },
        ...
      ],
       "NextMarker": null
}

In response, Lambda returns a list of up to 10 functions. If there are more functions you can retrieve, NextMarker provides a marker you can use in the next list-functions request; otherwise, the value is null. The following list-functions AWS CLI command is an example that shows the --marker parameter.

$ aws lambda list-functions --max-items 10 \
--marker value-of-NextMarker-from-previous-response

Retrieve a Lambda Function

The Lambda CLI get-function command returns Lambda function metadata and a presigned URL that you can use to download the function's deployment packagen.

$ aws lambda get-function --function-name helloworld
{
    "Code": {
        "RepositoryType": "S3",
        "Location": "pre-signed-url"
    },
    "Configuration": {
        "FunctionName": "helloworld",
        "MemorySize": 128,
        "CodeSize": 287,
        "FunctionArn": "arn:aws:lambda:us-west-2:account-id:function:helloworld",
        "Handler": "index.handler",
        "Role": "arn:aws:iam::account-id:role/LambdaExecRole",
        "Timeout": 3,
        "LastModified": "2015-04-07T22:02:58.854+0000",
        "Runtime": "nodejs8.10",
        "Description": ""
    }
}

For more information, see GetFunction.

Clean Up

Execute the following delete-function command to delete the helloworld function.

$ aws lambda delete-function --function-name helloworld

Delete the IAM role you created in the IAM console. For information about deleting a role, see Deleting Roles or Instance Profiles in the IAM User Guide.