AWS Lambda

Serverless compute.

Allows you to run code without managing servers.

Provides compute by running code in response to an event (event-driven).

When an event happens, that event will trigger a lambda function.

The lambda function will run your code in response to that event.

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AWS Lambda is a serverless, event-driven compute service that lets you run code
for virtually any type of application or backend service without provisioning/managing servers.

You can trigger lambda from over 200 AWS services and software as a service (SaaS) applications, and only pay for what you use.
Only need to pay for the time when the code is running.

Use Case

AWS Lambda is best for those types of situations when you need to run code
when any type of event happens.

• It's serverless - you don't need to manage the underlying server.
• If you start sending more requests to that lambda function, it'll scale itself automatically.
  • It automatically scales up and down, based on the traffic going into it.

Lambda functions can run for up to 15 minutes, and if something is required to run randomly
based on conditions, severless functions may be the way to go.
Up to 1000 AWS Lambda instances may be spawned at once.

Scaling with Lambda

There are two types of scaling: Horizontal and Vertical.
Horizontal scaling:
* Adding more instances of existing services.
* Adding additional compute loads* (more requests can be handled simultaneously).
* Fanning out left to right: horizontal scaling.

• Vertical scaling:
  • Giving the service more horsepower: vCPU and compute power.
  • Adding additional compute power is vertical scaling.

So, you can assign resources to a lambda function (scaling vertically).
i.e., assigning it more RAM, etc.
It's very good at scaling horizontally (spinning up more instances of that lambda.)
It automatically scales when you send traffic to it.
Lambda Functions can scale horizontally with a concurrency limit of 1000

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