Ephemeral Workloads: Embracing Stateless Cloud-Native Applications

Ephemeral workloads are a cornerstone of cloud-native technology, offering enhanced resilience and scalability. This article delves into the architecture of these transient systems, emphasizing the importance and complexities of implementing stateless applications in a cloud-native framework. 

We will dissect real-world scenarios to distill effective strategies for the development, deployment, and maintenance of stateless applications, particularly in Kubernetes and similar orchestration platforms.

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What are Ephemeral Workloads?

Ephemeral workloads are a fundamental component of container orchestration platforms like Kubernetes, especially now that some ops teams are operating as many as 10 clusters and tackling rising levels of complexity.

To understand how ephemeral workloads work, we first need to understand Pods, the smallest deployable units that can be created and managed.

Pods are created to be easily disposable and replaceable. Therefore, a container cannot be added to them. Pods are typically deleted and replaced as and when needed via deployments (the change or modification of states). 

In some cases, a developer may need to inspect a pod’s current state, perhaps to troubleshoot bugs that have proved difficult to replicate. This is where ephemeral containers come in, which are run to inspect the state of a pod and run various commands. 

Once the ephemeral container has completed its administrative function, it will not be restarted. These containers are also run using the existing resource allocation of the pod while sharing common container namespaces, making them very lightweight. 

How are Ephemeral Containers Different From Other Containers?

The key difference between ephemeral containers and other containers is that they do not guarantee resources or execution and will never be restarted automatically. However, like normal containers, ephemeral containers cannot be modified or removed once added to a pod. 

Although they have the same ContainerSpec as other containers, most fields are disallowed and cannot be used by ephemeral containers. Also, an ephemeral container might not have any ports, meaning fields such as Ports, LivenessProbe, and ReadinessProbe cannot be used. Until you become familiar with all the allowed fields, refer to the Kubernetes API reference documentation. 

Moreover, each ephemeral container is created using a specific EphemeralContainers handler within the API of the orchestration platform. This is instead of adding them directly to pod.spec, so these containers cannot be added using the kubectl edit command in Kubernetes. 

Ephemeral Containers: Key Uses

A primary use case for ephemeral containers is interactive troubleshooting when normal debugging tools have been exhausted. This could be because a container has crashed or the container image does not provide any debugging utilities. Distroless images are a prime example of this.

An ephemeral container can be injected into a pod that’s causing issues, allowing developers to check files, collect logs, run commands and even install diagnostic tools. Such a diagnostic protocol is especially helpful when replicating or diagnosing problems in a static environment has proved difficult. 

Other ephemeral use cases include:

• Instantly collecting logs and performing analysis to identify issues within a pod
• Recovering and repairing data without impacting the pod that is running
• Monitoring and analyzing resources to optimize pod performance

Stateless Applications in a Cloud-Native Environment

Understanding the versatile utility of ephemeral containers leads us naturally to the realm of stateless applications, particularly in cloud-native environments. 

These applications, free from the constraints of maintaining state, leverage the transient nature of ephemeral workloads to their advantage. This seamless integration is necessary for enhancing the efficiency of Kubernetes clusters, taking advantage of the lack of data storage and the option to add new instances. 

Within an orchestration platform such as Kubernetes, an application can be stateless or stateful. 

• Stateless applications do not persist state and utilize ephemeral workloads; this effectively means that the application uses temporary resources to run, which are then expunged when a pod is deleted or shut down. 
• Stateless applications require minimal resources to perform their function and disappear when they have completed their task.

Workloads within stateful applications meanwhile, require persistent storage, typically external storage such as network-attached or remote.  

In this context, cloud-native means building, deploying and managing applications in an environment that uses cloud-computing architecture. This environment requires lightweight applications that are highly scalable, resilient, and flexible so that they can be modified and updated quickly to meet the demands of the user. This is why stateless applications are more suitable. 

The finance industry is a great example of this, such as the execution of same-day ACH transfers that are often handled by ephemeral workloads and stateless applications, which ensure high availability, scalability, and rapid transaction processing essential for interbank transactions to work without a hitch.

Advantages of Stateless Applications

The key advantage of a stateless application is it can run on temporary memory and does not store any information between sessions, thus sapping available resources. 

This is similar to an HTML application that does not store user information. Instead, this information is stored in digital files called cookies that are saved on the user’s network or client. When a user revisits a website, the browser will then load the relevant cookies to retrieve details about the previous session. 

Other advantages include:

• Stateless applications are beneficial because they have no control over the resident memory on a system, making them less costly and easier to design and maintain when compared to a stateful application. 

• As stateless apps process each request separately, they are also more scalable, making it possible to add new instances without causing any state consistency or load-balancing issues.
• As state-across requests are not stored, a single failure will not affect the rest, increasing system fault tolerance. 

Disadvantages of Stateless Applications

As stateless applications need to send all the data with each request for session management, this makes them less efficient and results in lower performance and latency. A stateful application contains everything it needs to perform its function and can be recalled at any time, making them more convenient and capable of having a wider range of use cases. 

Fortunately, this downside is not particularly relevant in a cloud-native environment that relies on speed and needs to be scaled and modified seamlessly. Stateful applications are more suitable for edge computing environments that have an abundance of resources.

Other disadvantages include:

• Activities performed by stateful applications can complicate stateless apps, requiring mechanisms to manage states across multiple requests. E.G databases that manage state across requests.
• Stateless architecture is not suitable for designing applications that involve real-time collaboration, chat functionality, or gaming features. 

Examples of Stateless Applications

Web servers are an obvious example of stateless applications in action as they respond to requests without any state information, as do DNS servers which convert domain names to IP addresses. Content Delivery Networks (CDNs) like Cloudflare or Amazon CloudFront also cache and distribute content without state information. 

Meanwhile, there has been an increase in the use of stateless apps in everyday software, such as web-based PDF editors, to-do apps, and anything that can benefit from a lack of reliance on sessions. This increases the overall rigidity of the system, especially when handling data that requires a security clearance. 

Nevertheless, there are still proponents of using Kubernetes to deploy stateful applications, once again emphasizing the growing schism between the two camps. 

Developing, Deploying and Managing Stateless Applications: Best Practices

Below are five best practices to follow when developing, deploying, and managing stateless applications, ensuring security, scalability and more. 

1. Use managed services to maintain stateless applications, including automatic scaling, backups, and security monitoring.
2. If you do not use a managed service then it is recommended to use auto-scaling tools that adjust capacity to meet demand. 
3. Implement a fault-tolerant architecture to ensure a high level of system availability and resilience. This architecture runs backup components when needed to maintain performance levels. 
4. Use encryption to secure stateless apps, while also adhering to best practices to create a secure development environment and CI/CD pipeline. 
5. Install monitoring and logging software to quickly identify any bugs within the application and highlight any drops in performance. 

Artificial intelligence and machine learning are also helping to make stateless apps more secure and efficient by automating the testing stages during development. This ensures bugs are not missed and a developer can better allocate their time to focus on improving app performance. 

AI promises to improve efficiency when both developing and maintaining stateless cloud-native apps, as well as optimize costs and enhance security. There’s a reason why global investment in AI was already $92 billion in 2022, much of it due to the necessity to optimize app developments. 

Conclusion

Stateless applications are ideal for cloud-native environments as they use temporary storage to run and do not store information thanks to the use of ephemeral workloads. As a result, stateless apps are not as resource-heavy as stateful apps and are more scalable and resilient. 

Not only this, but stateless architecture is also less complex, making it more cost-effective and easier to develop a range of cloud-native applications. From web servers to CDNs, stateless applications are the perfect solution for any application that does not require any state information to function.