AWS Lambda vs Fission on EKS: A Clear Comparison

In this post we explore the real differences between AWS Lambda vs Fission on EKS. We keep things simple and straightforward because the decision is not just about raw compute numbers but also about the time and effort required from your team. This discussion assumes you already have an EKS cluster since setting up a cluster just to run Fission functions would not make sense. We also include an example of spot instances on EKS because those savings can be hard to ignore (typically around 60% vs on-demand nodes).

You will learn about the cost structure, maintenance effort, and scenarios when each option makes sense. Whether you value simplicity or flexibility, the key is understanding how much management your team is willing to invest.

AWS Lambda: Simple, Quick, and Easy to Use

AWS Lambda offers a serverless computing solution that allows you to run functions without thinking about infrastructure. You do not manage servers or clusters; you simply pay for the requests and the compute time your functions use. This model lets you focus entirely on writing and updating your code while AWS handles scaling and management.

Lambda charges you based on two factors: how often your function runs and how long it runs. For example, if you run a function with 128MB of memory for 1 million requests per month, you might spend about $0.62 in total. If you increase to 10 million requests, the cost rises to around $6.20 per month. This pay-per-use model works especially well for sporadic workloads such as APIs that are hit only a few times a day.

Key points for AWS Lambda include:

• You pay for function invocations and the compute time consumed.

• There is minimal infrastructure management required, which means lower maintenance costs.

These benefits mean that when your workload is bursty or unpredictable, Lambda can be extremely cost-effective especially if you cost optimize your Lambda functions. Moreover, your team saves time and money because there is no need to manage or scale the underlying infrastructure.

Fission on EKS: Flexibility and Control with Added Responsibility

Fission on EKS brings serverless functions to your own Kubernetes cluster. This option gives you more control over your serverless environment, allowing you to scale, tune, and optimize based on your specific needs. However, this flexibility comes at a cost because you are responsible for managing the EKS cluster and ensuring that everything runs smoothly.

When using Fission on EKS, your cost comes from the compute resources within your EKS cluster. For example, if you run a function on an m5.large EC2 instance (with 2 vCPUs and 8GB of RAM) and your function uses 25 percent of that instance’s capacity, you would pay roughly $0.024 per hour for that function. Over the course of a month, that might amount to around $17.52 for one continuously running function.

Key points for Fission on EKS include:

• You gain full control over how your functions are deployed on Kubernetes.

• You incur personnel costs and additional management overhead since you must maintain your cluster.

This flexibility allows you to optimize performance and leverage features like spot instances to lower costs further. However, be aware that someone on your team must handle Kubernetes management tasks, which may increase overall personnel expenses.

Fission on EKS with Spot Instances: Extra Savings for Flexible Workloads

When you run Fission on EKS using spot instances, you can dramatically reduce your compute costs. Spot instances can lower your EC2 costs by anywhere from 30 to even 90 percent in some extreme circumstances. For example, if you use an m5.large instance at on-demand pricing of $0.096 per hour, using spot pricing might lower that rate to around $0.03 per hour. At 25 percent usage, you could pay about $0.0075 per hour. Over a month, this amounts to roughly $5.48 per month for that function, compared to $17.52 per month on on-demand pricing.

Key points for using spot instances with Fission on EKS include:

• You save significantly on compute costs when using discounted spot instances.

• Spot instance interruptions require careful handling and make sense only for non-critical or flexible workloads.

While spot instances can lower costs dramatically, they come with the risk of interruption. This makes them best suited for workloads that can tolerate pauses or restarts. By leveraging spot instances, you can cut your compute expenses without sacrificing the benefits of running serverless functions on your own Kubernetes cluster.

When to Use AWS Lambda

AWS Lambda shines when you want to eliminate infrastructure management and focus on your code. It is ideal for bursty or unpredictable workloads where you do not want to worry about idle compute time or scaling issues. Lambda offers clarity in costs because you know exactly what you will pay each month based on your usage.

Lambda works best when:

• Traffic is unpredictable and you pay only for the function’s active time.

• You want a hands-off approach that removes the need for dedicated infrastructure management.

For example, if you run a website that gets only a few thousand requests per day, Lambda can be extremely cost-effective. Running 5,000 requests per day may cost around $93 per year. Its simplicity and ease of scaling make it a stress-free option for many applications.

When to Use Fission on EKS

Fission on EKS makes sense if you already run Kubernetes and want to extend your serverless capabilities. It gives you granular control over how your functions run and allows you to optimize resource allocation. Fission is particularly attractive when you handle high traffic or continuous workloads and wish to leverage spot instances to further reduce costs.

Fission on EKS is ideal when:

• Your team already has Kubernetes expertise.

• You run high-volume or continuous workloads that benefit from detailed control.

• You want to use spot instances for non-critical functions to lower overall costs.

For instance, consider a data pipeline processing 30 million events per month. Running that pipeline in Lambda might cost around $186 per month. By deploying it in Fission on EKS with spot instances, you could potentially reduce the cost to about $30 per month, provided your team is prepared to manage the cluster.

Maintenance and Personnel Considerations

Maintenance is a major factor in deciding between AWS Lambda and Fission on EKS. With Lambda, you do not need to manage infrastructure. AWS handles scaling and maintenance, which means you can save on dedicated DevOps personnel and operational overhead. This simplicity makes Lambda attractive for startups or small teams.

On the other hand, Fission on EKS requires active management of your Kubernetes cluster. Your team must invest time in monitoring, scaling, and optimizing the cluster, and you might need dedicated DevOps engineers. While this approach offers flexibility and control, it increases personnel costs and demands more attention to infrastructure management.

Final Thoughts: AWS Lambda vs Fission on EKS

The decision between AWS Lambda and Fission on EKS depends on your specific needs and existing infrastructure. If you prefer simplicity with zero infrastructure management and predictable costs, AWS Lambda is the best choice. It allows you to focus entirely on your code while AWS takes care of everything else.

If you already run an EKS cluster and need full control over your serverless functions, Fission on EKS is a powerful option. It provides flexibility, especially when combined with spot instances, to significantly cut costs. However, this option comes with added responsibility and increased personnel overhead.

Remember that the choice is not solely about raw compute costs. Consider the maintenance and management overhead as well. Sometimes the simpler option saves more in the long run by freeing up your team’s time and energy.

I hope this article helps you understand the tradeoffs between AWS Lambda and Fission on EKS. If you have any questions or need further details, feel free to reach out. Happy computing!