Download an already uploaded Lambda function

I created a lambda function in AWS (Python) using "upload .zip" I lost those files and I need to make some changes, is there is any way to download that .zip?

Yes!

Navigate over to your lambda function settings and on the top right you will have a button called "Actions". In the drop down menu select "export" and in the popup click "Download deployment package" and the function will download in a .zip file.

Action button on top-right

A popup from CTA above (Tap "Download deployment package" here)

Update: Added link to script by sambhaji-sawant. Fixed Typos, improved answer and script based on comments!

You can use aws-cli to download the zip of any lambda.

First you need to get the URL to the lambda zip $ aws lambda get-function --function-name $functionName --query 'Code.Location'

Then you need to use wget/curl to download the zip from the URL. $ wget -O myfunction.zip URL_from_step_1

Additionally you can list all functions on your AWS account using

$ aws lambda list-functions

I made a simple bash script to parallel download all the lambda functions from your AWS account. You can see it here :)

Note: You will need to setup aws-cli before using the above commands (or any aws-cli command) using aws configure

Full guide here

You can use shell script available here

If you want to download all the functions in the given region here is my workaround. I have created a simple node script to download function. Install all the required npm packages and set your AWS CLI to the region you want before running the script.

let download = require('download-file');
let extract = require('extract-zip');
let cmd = require('node-cmd');

let downloadFile = async function (dir, filename, url) {
    let options = {
        directory: dir,
        filename: filename
    }
    return new Promise((success, failure) => {
        download(url, options, function (err) {
            if (err) {
                failure(err)
            } else {
                success('done');
            }
        })
    })
}

let extractZip = async function (source, target) {
    return new Promise((success, failure) => {
        extract(source, { dir: target }, function (err) {
            if (err) {
                failure(err)
            } else {
                success('done');
            }
        })
    })
}

let getAllFunctionList = async function () {
    return new Promise((success, failure) => {
        cmd.get(
            'aws lambda list-functions',
            function (err, data, stderr) {
                if (err || stderr) {
                    failure(err || stderr)
                } else {
                    success(data)
                }
            }
        );
    })
}

let getFunctionDescription = async function (name) {
    return new Promise((success, failure) => {
        cmd.get(
            `aws lambda get-function --function-name ${name}`,
            function (err, data, stderr) {
                if (err || stderr) {
                    failure(err || stderr)
                } else {
                    success(data)
                }
            }
        );
    })
}

let init = async function () {
    try {
        let { Functions: getAllFunctionListResult } = JSON.parse(await getAllFunctionList());
        let getFunctionDescriptionResult, downloadFileResult, extractZipResult;
        getAllFunctionListResult.map(async (f) => {
            var { Code: { Location: getFunctionDescriptionResult } } = JSON.parse(await getFunctionDescription(f.FunctionName));
            downloadFileResult = await downloadFile('./functions', `${f.FunctionName}.zip`, getFunctionDescriptionResult)
            extractZipResult = await extractZip(`./functions/${f.FunctionName}.zip`, `/Users/malhar/Desktop/get-lambda-functions/final/${f.FunctionName}`)
            console.log('done', f.FunctionName);
        })
    } catch (e) {
        console.log('error', e);
    }
}


init()

You can find a python script to download all the lambda functions here.

import os
import sys
from urllib.request import urlopen
import zipfile
from io import BytesIO

import boto3

def get_lambda_functions_code_url():

client = boto3.client("lambda")

lambda_functions = [n["FunctionName"] for n in client.list_functions()["Functions"]]

functions_code_url = []

for fn_name in lambda_functions:
    fn_code = client.get_function(FunctionName=fn_name)["Code"]
    fn_code["FunctionName"] = fn_name
    functions_code_url.append(fn_code)

return functions_code_url


def download_lambda_function_code(fn_name, fn_code_link, dir_path):

    function_path = os.path.join(dir_path, fn_name)
    if not os.path.exists(function_path):
        os.mkdir(function_path)

    with urlopen(fn_code_link) as lambda_extract:
        with zipfile.ZipFile(BytesIO(lambda_extract.read())) as zfile:
            zfile.extractall(function_path)


if __name__ == "__main__":
    inp = sys.argv[1:]
    print("Destination folder {}".format(inp))
    if inp and os.path.exists(inp[0]):
        dest = os.path.abspath(inp[0])
        fc = get_lambda_functions_code_url()
        print("There are {} lambda functions".format(len(fc)))
        for i, f in enumerate(fc):
            print("Downloading Lambda function {} {}".format(i+1, f["FunctionName"]))
            download_lambda_function_code(f["FunctionName"], f["Location"], dest)
    else:
        print("Destination folder doesn't exist")

Here is a bash script that I used, it downloads all the functions in the default region:

download_code () {
    local OUTPUT=$1
    OUTPUT=`sed -e 's/,$//' -e 's/^"//'  -e 's/"$//g'  <<<"$OUTPUT"`
    url=$(aws lambda get-function --function-name get-marvel-movies-from-opensearch --query 'Code.Location' )
    wget $url -O $OUTPUT.zip
}

FUNCTION_LIST=$(aws lambda list-functions --query Functions[*].FunctionName)
for run in $FUNCTION_LIST
do
    download_code $run
done

echo "Finished!!!!"