# **What is PaaS?**

platform-based service is a category of **cloud computing** services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.

## **Advantages**
* allows for higher-level programming with dramatically reduced complexity
* the overall development of the application can be more effective
* Infrastructure savings
* easy to maintenance and enhancement of the application

## **Disadvantages**
* increased pricing at larger scales
* lack of operational features
* reduced control
* the difficulties of traffic routing systems

## Heroku

Heroku is a container-based cloud Platform as a Service (PaaS). Developers use Heroku to deploy, manage, and scale modern apps.

## How deploy in Heroku?

[Press here](https://devcenter.heroku.com/articles/getting-started-with-nodejs#set-up)

# What is environment variable ?
An environment variable is a key and value pair that is stored on the local system where your code/app is being run and is accessible from within your code.
For example
username and language of the operation system.

LANG=en_IL
DISPLAY=:0
USERNAME=ebraheem
DESKTOP_SESSION=ubuntu
LANGUAGE=en_IL:en

# why to change the environment variable?
The most well known environment variable is probably PATH which contains the paths to all folders that might contain executables.
So in diiferent env we have to change the PATH veriable to execute the code properly.

Some env variable contain some personal info , so be aware which env variable u include.

# How to manage environment variable
We can manage environment variable by putting all of them in json file
like this
{
"DB_HOST": "127.0.0.1",
"DB_PORT": 9200,
"DB_USER": "anon",
"DB_PASS": "password"
}
and send it with the code to the new environment