Advantages and Disadvantages of FaaS

Advantages of FaaS

It is cheap, really

An AWS Lambda costs as little as $0.20 per million requests and $0.0000166667 for every GB-second. This means you can build a microservice without burning a hole in your pocket.

Highly scalable

Every concurrent invocation will create a separate instance of the service. There is almost no limit to how much a FaaS can scale horizontally, except maybe your budget.

Disadvantages of FaaS

Cold starts

Every concurrent invocation initialises a new instance of the service. This will require time for it to initialise, also known as cold start. However, there are ways to avoid this. AWS has provisioned concurrency which helps to resolve cold starts with an additional cost. This will keep a specified number of instances warm.

Denial of Service

Because your architecture is highly scalable, you may be vulnerable to DoS. This might burn a hole in your pocket. Thankfully there is service level throttling when you reach the burst limit, thus reducing the damage. However, this might be an issue when you have a spike in legitimate traffic.

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