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This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 400,000 packages pre-installed, including aws-lambda-local with all npm packages installed. Try it out:

var awsLambdaLocal = require("aws-lambda-local")

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aws-lambda-local v2.0.6

Run AWS Lambda functions locally! The most lightweight library - no external dependencies. Only 100 lines of code.


Run AWS Lambda function locally! The most lightweight library - no external dependencies. Less than 200 lines of code.

Windows, Mac and Linux tested!


npm install -g aws-lambda-local


-f functionName     | --function=functionName       required       Path to Lambda function main file
-e event            | --event=event                 optional       Either path to .json file contains event object or raw JSON data
-c contextPath      | --context=contextPath         optional       Path to .json file contains context object
-t seconds          | --timeout=seconds             optional       Force quit Lambda function after XX seconds
-h handler          | --handler=exports.handler     optional       Module.exports.handler name. Default is first function from the module 


Just specify function name (can be in nested directory), event object file. Optionally you also may replace default context object and timeout (30 seconds by default).

$ cat function.js

exports.handler = function(event, context)
    context.done(event, context);
    // or
    return new Promise((resolve, reject) => {})


exports.handler = function(event, context, callback)
    callback(null, dataToRetun);


exports.handler = function(event)
    return new Promise((resolve, reject) => {})

Or even

exports.handler = async (event) =>
    return 'ret';

Check the event object. You can create any set of input data (and use them for functional testing or something else)

$ cat event.json
    "obj"   : { "a" : "b" },
    "int"   : 1,
    "str"   : "qwerty",
    "arr"   : [ 1, 2, 3, 4 ]

$ lambda-local -f function -e event.json -t 20
    "obj": {
        "a": "b"
    "int": 1,
    "str": "qwerty",
    "arr": [
    "awsRequestId": "wn26j4dm-m8zd-d7vi-j94j-50t4zsjlwhfr",
    "logGroupName": "/aws/lambda/function",
    "logStreamName": "2015/11/12/[$LATEST]wn26j4dmtm8zd7vij94j50t4zsjlwhfr",
    "functionName": "function",
    "memoryLimitInMB": "128",
    "functionVersion": "$LATEST",
    "invokedFunctionArn": "arn:aws:lambda:aws-region:1234567890123:function:function",
    "invokeId": "wn26j4dm-m8zd-d7vi-j94j-50t4zsjlwhfr"

Other ways to pass the input event:

$ lambda-local -f function -e event.json
$ lambda-local -f function -e '{"json":"here"}'
$ cat event.json | lambda-local -f function
$ echo '{"json":"here"}' | lambda-local -f function

CLI script will return non-zero exit code (1) in case of any failure.

If you missed to call context.succeed()|fail()|done() function and your Lambda function runs forever - just use timeout option!

Check out my aws-lambda-build package!


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