I recently started building a Slack Application linked to a booking API. The API is deployed in AWS Lambda, and it's developed locally using Serverless Offline.

When handling user interactions, Slack requires an acknowledgment within 3 seconds, but with the booking API, it's not possible to complete the request within 3 seconds, especially when creating a booking.

Therefore, I used one function for the acknowledgment, and another function to handle the request and return data. In AWS docs, this was quite simple. Using aws-sdk, we can trigger another function.

const {Lambda} = require("aws-sdk");

const lambda = new Lambda();

const payload = {...}

const params = {
  FunctionName: `my-api-${process.env.STAGE}-handleProcessA`,
  InvocationType: "Event",
  LogType: "None",
  Payload: JSON.stringify(payload),
};

await lambda.invoke(params).promise();


This code works perfectly fine when deployed to AWS, but not locally with serverless offline. To use this with serverless offline, we need to pass the endpoint variable, which is also mentioned in the docs from Serverless Offline.

const {Lambda} = require("aws-sdk");

const lambda = new Lambda({
  endpoint: process.env.IS_OFFLINE
    ? 'http://localhost:3002'
    : 'https://lambda.us-east-1.amazonaws.com',
});

const payload = {...}

const params = {
  FunctionName: `my-api-${process.env.STAGE}-handleProcessA`,
  InvocationType: "Event",
  LogType: "None",
  Payload: JSON.stringify(payload),
};

await lambda.invoke(params).promise();


For the API's local development, I was using the port 8002, and when using the above code, I changed the port 3002 to be 8002. And running this returned an error: "Unsupported Media Type"

I searched in SO and found these two questions, but still, it didn't solve the issue.

Unable to invoke a lambda from another lambda using aws serverless offline

"Unsupported Media Type" using serverless offline

The answers to those two questions didn't work for me, so I posted [a new question in SO.] (https://stackoverflow.com/questions/73718753/how-to-invoke-a-lambda-function-from-another-lambda-in-serverless-offline)

After all that, I got another direction and started looking at the [CLI options](https://www. serverless.com/plugins/serverless-offline#usage-with-invoke) of Serverless Offline again. That's when I realised that there were two ports: --httpPort and --lambdaPort.

When invoking lambda functions, the --lambdaPort should be used. I was using the --httpPort and that's what gave me the error.

They have mentioned to setting serverless-offline endpoint. But I think it would be better understood in this way:

"To use Lambda.invoke you need to set the lambda endpoint to the serverless-offline endpoint with the --lambdaPort."

Invoking a lambda functions locally from another lambda is pretty easy. But there's a catch.

Invoking Lambda Functions Locally with Serverless Offline

I set up a tiny Laravel App in AWS last weekend This was the fourth time that I had to deploy in AWS, but still it took me a considerable amount of time.

This is the cheatsheet with all the commands for deploying Laravel, setting up the domain and SSL on AWS LAMP 20.

sudo chown $USER /opt/bitnami/projects/<FOLDER-NAME>


sudo chown -R daemon:daemon /opt/bitnami/projects/<FOLDER-NAME>/storage


mysql> create user 'USER_NAME'@'%' identified by 'PASSWORD';


mysql> grant all privileges on DATABASE_NAME.* TO 'USER_NAME'@'%';


APP_URL=https://your-domain.com

DB_CONNECTION=mysql
DB_HOST=localhost
DB_PORT=3306
DB_DATABASE=<DB_NAME>
DB_USERNAME=<USER_NAME>
DB_PASSWORD=<DB_USER_PASSWORD>


Create the /opt/bitnami/apache2/conf/vhosts/<FOLDER-NAME>-vhost.conf with following:

<VirtualHost 127.0.0.1:80 _default_:80>
  ServerAlias *
  DocumentRoot /opt/bitnami/projects/<FOLDER-NAME>/public
  RewriteEngine On
  RewriteCond %{HTTPS} !=on
  RewriteRule ^/(.*) https://%{SERVER_NAME}/$1 [R,L]
  <Directory "/opt/bitnami/projects/<FOLDER-NAME>/public">
    Options -Indexes +FollowSymLinks -MultiViews
    AllowOverride All
    Require all granted
  </Directory>
</VirtualHost>


Create the /opt/bitnami/apache2/conf/vhosts/<FOLDER-NAME>-https-vhost.conf with following:

<VirtualHost 127.0.0.1:443 _default_:443>
  ServerAlias *
  DocumentRoot /opt/bitnami/projects/<FOLDER-NAME>/public
  SSLEngine on
  SSLCertificateFile "/opt/bitnami/apache2/conf/bitnami/certs/server.crt"
  SSLCertificateKeyFile "/opt/bitnami/apache2/conf/bitnami/certs/server.key"
  <Directory "/opt/bitnami/projects/<FOLDER-NAME>/public">
    Options -Indexes +FollowSymLinks -MultiViews
    AllowOverride All
    Require all granted
  </Directory>
</VirtualHost>


sudo /opt/bitnami/ctlscript.sh restart apache


sudo apt-get install software-properties-common


sudo apt-add-repository ppa:certbot/certbot -y


sudo certbot -d $DOMAIN -d $WILDCARD --manual --preferred-challenges dns certonly


Now, update the TXT records and test it here

sudo mv /opt/bitnami/apache/conf/bitnami/certs/server.crt /opt/bitnami/apache/conf/bitnami/certs/server.crt.old


sudo mv /opt/bitnami/apache/conf/bitnami/certs/server.key /opt/bitnami/apache/conf/bitnami/certs/server.key.old


sudo ln -s /etc/letsencrypt/live/$DOMAIN/privkey.pem /opt/bitnami/apache/conf/bitnami/certs/server.key


sudo ln -s /etc/letsencrypt/live/$DOMAIN/fullchain.pem /opt/bitnami/apache/conf/bitnami/certs/server.crt


Cheatsheet for setting up Laravel 8 in AWS Lightsail LAMP

let list = ["item_0", "item_1", "item_2", "item_3"]


In the first two methods, I will be removing the second element, which is "baz" from the array. The end result will be ["item_0", "item_2", "item_3"]

// 1st value passed: the start element
// 2nd value passed: how many elements to be removed.


var final = list.splice(list.indexOf("item_1"),1)


Common methods to remove elements in JavaScript arrays

I used to work with moment, and then moved on to date-fns. Whenever I want to format a date other than yyyy-MM-dd, I have to go see the docs. So I'm adding my most used formatting strings here.

M       1, 2, ..., 12
Mo      1st, 2nd, ..., 12th	
MM      01, 02, ..., 12
MMM     Jan, Feb, ..., Dec
MMMM    January, February, ..., December


d       1, 2, ..., 31
do      1st, 2nd, ..., 31st
dd      01, 02, ..., 31


h       1, 2, ..., 11, 12	
ho      1st, 2nd, ..., 11th, 12th
hh      01, 02, ..., 11, 12


H       0, 1, 2, ..., 23	
Ho      0th, 1st, 2nd, ..., 23rd
HH      00, 01, 02, ..., 23


m       0, 1, ..., 59	
mo      0th, 1st, ..., 59th
mm      00, 01, ..., 59


s       0, 1, ..., 59	
so      0th, 1st, ..., 59th
ss      00, 01, ..., 59


a..aa   AM, PM	
aaa     am, pm	
aaaa    a.m., p.m.
aaaaa   a, p	
b..bb   AM, PM, noon, midnight	
bbb     am, pm, noon, midnight	
bbbb    a.m., p.m., noon, midnight
bbbbb   a, p, n, mi


X       -08, +0530, Z	
XX      -0800, +0530, Z	
XXX     -08:00, +05:30, Z	
XXXX    -0800, +0530, Z, +123456
XXXXX   -08:00, +05:30, Z, +12:34:56


x       -08, +0530, +00	
xx      -0800, +0530, +0000	
xxx     -08:00, +05:30, +00:00
xxxx     -0800, +0530, +0000, +123456	
xxxxx   -08:00, +05:30, +00:00, +12:34:56


Note: Full docs are available at date-fns official docs

After almost 3 years of just having a home page, I thought to start a blog.

The blog is supposed to make coding a bit easier for me. :D

Hey, I'm Mahesh.

Invoking Lambda Functions Locally with Serverless Offline

Laravel in AWS Lightsail