What is serverless?

by Zek Chak
Published on January 2021

In 2021, the buzzwords and hot topics of yesteryear are fast becoming standard practice. So if you’re still in the dark about serverless, now’s the time to swot up.

This article will provide you with everything you need to get a firm grasp of serverless basics, including:

  • What it actually is 
  • The technology trends that drove the development of serverless 
  • The pros and cons
  • What solutions are available today 
  • And finally, what makes a good serverless use case

So let’s get to it!

What is serverless

Serverless computing is – first and foremost – a misleading term. In solutions like peer to peer, it’s true there’s not a server in sight, but, in serverless solutions there are, in fact, servers galore.

surprised woman

So why the name?

Serverless actually means the developer takes no responsibility for provisioning. 

Instead the application’s business logic – the code that deals with core functionality – is fed into a serverless solution like AWS Lambda or Azure Functions, and then provisioning is handled on a per function basis.

This is why it’s called FaaS (function as a service).

This is a somewhat difficult concept to grasp, but you could say that serverless is the Uber of computing vs. the traditional set up of owning a car.

The user pays on a per journey basis with a new vehicle provided – and charged for – per trip. Which of course offsets the costs of insuring, maintaining and even learning to drive one’s own vehicle.

Serverless is much the same. There are servers. But they’re someone else’s problem.

How did we get here?

Serverless represents the latest iteration in a technology trend of an increasing focus on business logic and decreasing focus on provisioning infrastructure.

What’s business logic again?

Business logic – in software development – is the part of an application which encodes the real-world business rules.

This is really what the application does

So, a very simplified example might be something like ‘if a user hits play, begin the movie they’re trying to watch.’

So what’s this trend toward business logic?

A graph

Essentially, it’s a trend which says, ‘we want to write code, and we don’t want to maintain the environments it runs in.’

And it’s been gathering pace throughout each new approach to provisioning.

Beginning with…

1. BMs (bare metal servers) 

Here, the provisioning was literal. A warts-and-all bare metal server. You probably know all the ways in which this is inferior to a VM set-up. But for the purposes of understanding this trend, what’s important is that you maintain, patch, pay for at rest, and scale with extreme difficulty.

2. VMs (virtual machines)

The elementary particle of the cloud computing universe –  virtual machines were a significant improvement on bare metal.

By partitioning off sections of physical servers to create virtual machines, public cloud providers were able to supply a rapidly scalable, flexible and cheaper service. To add more machines, all they needed to do was allocate more (virtual) space. 

However, the user was still responsible for maintaining and patching.

3. Containers

Containers are a bit of a funny one, but in tracing the move away from environment, all we need to understand is that a container is like a virtual machine with one less layer of virtualization in between it and the provider’s server. 

This is grossly oversimplified – and you can get complicated here.

But essentially, getting rid of this layer made containers lighter and easier to work with, though users still had to maintain them, etc.

4. Serverless 

The endpoint of this trend is currently serverless – although, just to be clear, that doesn’t mean serverless is ‘better’ than all these other methods. What it is – however – is the furthest anyone’s got in totally removing environment form the equation.

So serverless architecture is? (example using AWS Lambda)

A graphic of serverless architecture

Here we can see static elements of the app are hosted in S3. That isn’t serverless.

However, when handling services requiring app data, API keys or identities, Lambda will spin up instances of the pictured services per request – that’s serverless.

So what are the pros and cons of serverless?

thumbs up and down

Pros 

1. Costs

Serverless is cheap, consumes no resources at rest, and because the FaaS provider takes such a huge chunk of what you’d normally be doing off your hands, the TCO (total cost of ownership) goes down enormously.

2. Frees up developer creativity

Concentrating only on business logic opens doors for more creative development, with teams unfettered by concerns about environment and provisioning.

3. Decreased time to market

A sub-benefit of the above, but such a substantial one it warrants its own entry. The time saved not provisioning means developers can finish up quickly, getting the application to market faster.

4. Improved geolocation

Because servers are spun up on-demand, it’s possible for the provider to run the function in an environment close to the user’s request, cutting down latency.

5. Scalability

Even VMs are often worked out on a pre-paid for expected compute basis – this generally being cheaper than pay-as-you-go. With serverless, there are no such constraints, since every function can be handled and scaled independently.

6. Microservices ready

Microservices applications can be implemented as functions, to find out more about microservices, read our thoughts here

Cons

1. Multi-Tenancy security issues

Because FaaS providers often perform function requests for multiple clients within the same server – this is what’s meant by multi-tenancy, i.e sharing a space – serverless solutions can be more vulnerable to certain kinds of attacks.

2. Vendor lock-in

It can be difficult migrating a serverless application between FaaS providers, and if they decide to change the cost, you might be stuck with it.

3. Cold starts

The first time your function calls up an environment, there can be increased latency. This is known as a ‘cold start,’ but it can be mitigated by having your application make routine calls to ‘keep your environment warm.’

4. Not the best approach for long-running tasks

Certain procedures – for example processing data – are better suited to dedicated servers. These are tasks that need to be ticking away in the background.

5. Lack of operational oversight 

Because serverless solutions spin up a new environment every time a function’s called, debugging, gathering relevant metrics on, and monitoring can be difficult – and you’re more often than not reliant on the provider.

6.  Architectural complexity 

Implementing a serverless architecture can be difficult, and a great deal of thought needs to go into how the application is split into different functions – although, of course, you do avoid the complexity of provisioning.

So what serverless solutions are out there? Serverless on AWS, Azure or Google?

Serverless or FaaS solutions are offered by all of the major cloud providers. There’s Lambda from AWS, Azure Functions and Google Cloud Functions, as well as a few other serverless, or serverless-ish offerings, such as AWS Fargate.

However, with serverless now a mature technology, the real difference between these services are miniscule.

All are highly available with the capability to support huge workloads. You could say Google supports the fewest number of coding languages – with languages supported being cited as a meaningful distinction by some – but really, most serverless concepts are implementable in any of the languages offered.

It’s often just a case of developer preference.

Interface-wise, some point to AWS Lamda’s more hold-you-by-the-hand, pop-up–box approach as a positive, making it less likely unseasoned devs will drop the ball, while some prefer the more stripped back interface of Azure.

The bottom line is that these technologies are roughly equal for most purposes, which again speaks to the fact that they’ve been developing for some years.

How to know whether to go serverless?

Serverless has many potential use cases. It can be great for: 

  • Start-ups or smaller companies who want to focus on their application only 
  • Static websites, where the speed and scalability of serverless outstrips VMs 
  • As part of a DevOps pipeline, where serverless solutions manage the environments needed for testing
  • Any workload that doesn’t need to be ‘always on,’ to take maximum advantage of the fact you’re paying nothing while idle

However, there’s more to it than that.

Ultimately, whether or not serverless is the right architecture for you is a very complex question, and though we’d be happy to weigh in, it’s not for a ‘What is…’ article.

It depends on your application, the overall business and technical context, and a whole lot else.

The takeaways

  • Serverless isn’t serverless. There are servers, they’re just managed by someone else
  • In serverless applications, servers spin up on a per function basis, with a function being an item of business logic
  • Serverless is part of a trend in which provisioning of environment is backgrounded and business logic is centred
  • There are pros and cons to serverless, including, in the plus column, low costs and availability, and in the minus, vendor lock-in and unsuitability for certain workloads
  • In 2021, there’s little meaningful difference between the three major FaaS solutions, AWS Lambda, Azure Functions, and Google Cloud functions
  • Whether or not to go serverless is a complex question – it’s great in some circumstances, but not all

How we can help

As a cloud-native MSP working with MACH technologies for a variety of leading brands, Just After Midnight are perfectly placed to help you take advantage of emerging tech.

So, if you think serverless might be the way to go, or you just want pointing in the right direction, get in touch.

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