Exploring Knative: The Future of Serverless on Kubernetes

Are you ready to revolutionize the way you develop, deploy, and manage serverless applications? Knative is an open-source project that brings serverless capabilities to Kubernetes, enabling developers to build, deploy, and manage serverless applications with ease. In this blog post, we will uncover the power of Knative and how it can transform your serverless journey.

Unpacking Knative: The Serverless Services Powerhouse

What is Knative?

Knative, an open-source project rooted in Kubernetes, is engineered to provide a platform that enables building, deploying, and administering serverless workloads. Knative consists of two main components: Serving and Eventing, which serve as the building blocks for constructing, deploying, and managing serverless workloads on Kubernetes. This powerful combination enables developers to focus on writing code without having to manage their applications’ build, deployment, and maintenance, allowing them to run serverless workloads efficiently on Kubernetes.

With serverless computing gaining popularity, many organizations assume that they need to adopt a specific cloud provider’s serverless platform. However, Knative offers a Kubernetes-native way to build, deploy, and manage serverless applications, avoiding vendor lock-in. This versatile nature allows you to tap into the power of Kubernetes and Linux containers, simplifying the creation of modern, cloud-native applications.

Knative Architecture Explained

The architecture of Knative is primarily composed of two components: Serving and Eventing. Knative Serving deploys containers and offers generic service models, while Knative Eventing manages global event subscription, delivery, and management. These components collaborate to enable serverless workloads triggered by events, providing a flexible and scalable platform for creating modern, cloud-native applications.

Taking advantage of the power of Kubernetes and Linux containers, Knative offers a platform that simplifies the construction, deployment, and administration of serverless workloads, thus making the development and management of serverless applications on Kubernetes more efficient.

The Role of Istio in Knative

Istio, recognized as a service mesh, holds a significant role in Knative by handling traffic routing, revisions, and metrics for serverless workloads. As a service mesh solution, Istio provides security, monitoring, and containerization to manage microservice components, utilizing gateways to control incoming and outgoing traffic from the mesh, thereby allowing precise control of traffic flow.

Istio integrates with Knative by deploying the Knative Istio controller, enabling Knative to leverage Istio’s service mesh capabilities. Istio manages traffic routing in Knative through the utilization of the ‘traffic’ stanza in the Knative service, providing seamless management of serverless workloads.

Getting Started with Knative Deployment

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Having gained a better understanding of Knative’s architecture, we can now proceed to the process of installing and deploying Knative on a Kubernetes cluster. In the following sections, we will guide you through the prerequisites for installation and demonstrate how to deploy your first Knative service.

Prerequisites for Installation

Before you install Knative, ensure you have the necessary tools and a compatible Kubernetes cluster set up. Knative requires a minimum version of Kubernetes v1.19 and hardware requirements of 8GB of memory and 6 CPU cores.

It is also advised to confirm that the Istio component pods are running before initiating the installation of Knative components.

Deploying Your First Knative Service

Upon meeting the prerequisites, you can proceed with deploying your first Knative service. Knative enables you to use simplified YAML configurations and custom CRDs to deploy your serverless applications with ease. The process of deploying a Knative service involves:

1. Utilizing the kn command to deploy your service with a simplified configuration
2. Automating the container building process
3. Allowing you to focus on writing code

To create instances of the custom resource, first, define the CRD, install it into the cluster, and then use it to create instances of the custom resource. This process eliminates the need for manual containerization, allowing you to deploy serverless applications seamlessly.

Scaling Serverless Workloads with Knative

Knative enables efficient scaling of serverless workloads by providing autoscaling and resource management features. In this section, we will explore Knative’s autoscaling mechanics and discuss how to manage resources and limits for your serverless applications.

Autoscaling Mechanics

Knative’s autoscaling enables you to dynamically adjust the number of Kubernetes pods in response to traffic patterns, allowing for efficient resource utilization. By defining the number of requests per second each pod can handle, Knative’s infrastructure can scale up to meet higher loads or scale down to zero when idle, optimizing resource utilization.

However, it’s important to note that the Knative autoscaler is not capable of scaling services down to zero; it is only able to scale up based on CPU consumption. To scale down to zero, the Knative autoscaler sets the replica desired pod count to zero after no HTTP traffic has been detected for a few days.

Managing Resources and Limits

It is paramount to manage resources and set limits for your serverless applications in Knative for optimum performance and reliability. Knative provides built-in features for scaling and resource allocation, allowing for easy deployment and management of serverless applications, giving you complete control. Features such as scale to zero and traffic splitting help optimize resource usage.

To set resource limits in Knative, the queue proxy memory and CPU request/limit parameters can be adjusted. By doing so, you can ensure that your serverless applications run smoothly and efficiently, avoiding potential resource allocation issues and maintaining the stability of the application.

Streamlining Serverless Application Deployment

Knative simplifies the deployment of serverless applications by easing YAML configurations and automating the conversion of containers to URLs. In this section, we will explore how Knative uses simplified YAML configurations and custom CRDs to make deploying serverless applications easier.

From Container to URL: The Knative Way

Knative automatically converts containers to URLs, allowing developers to focus on writing code without having to manage their applications’ build, deployment, and maintenance. Knative Build enables you to declare transformations on the source code, such as converting functions to apps and apps to containers, which eliminates the need for manual containerization and allows for seamless deployment of serverless applications.

By utilizing subdomains to facilitate the translation of containers into URLs, Knative enables the underlying container to manage multiple URLs. This feature allows for:

• The creation of serverless environments using containers
• Facilitating agile application development and deployment
• Enhancing infrastructure management convenience and efficiency
• Allowing applications to automatically scale based on demand.

Knative Eventing: Building Reactive Serverless Applications

This section will cover Knative Eventing and its role in the construction of reactive serverless applications. We will discuss how to create and manage event sources in Knative and how to trigger functions with events.

Creating and Managing Event Sources

Event sources in Knative are components that generate events and make them accessible to the Knative eventing system. These event sources can be external systems, like message queues or databases, or internal components within the Knative cluster. Event sources are essential in enabling event-driven architectures and permit applications to respond to events in a decoupled and scalable manner.

Creating event sources in Knative can be achieved by writing custom Knative eventing sources or utilizing traditional event producers like Kafka, GitHub webhook, NATS, and Redis events. By effectively managing event sources, you can build powerful event-driven serverless applications on Knative.

Triggering Functions with Events

Knative Eventing provides Broker and Trigger objects to enable event filtering, while EventBridge can be utilized to trigger a Knative service by sending specific events, such as uploading files to Object Storage, via generic HTTP requests or CloudEvents. This seamless integration of event-driven workflows allows you to build powerful serverless applications with Knative.

By utilizing either generic HTTP requests or CloudEvents, you can create events to trigger functions in Knative. This enables smooth integration and communication between different services and components within the serverless architecture, allowing you to build robust, event-driven applications.

Cross-Platform Serverless with Knative

Knative provides cross-platform serverless capabilities, permitting developers to construct and deploy serverless applications across numerous cloud providers, with one such platform being particularly popular. In this section, we will explore the portability and open-source tools provided by Knative and discuss how to perform progressive rollouts across multiple clouds.

Portability and Open Source Tools

Knative provides a cloud-native and cross-platform orchestration standard for serverless applications, enabling deployment of serverless functions and applications across various platforms, including Kubernetes. This flexibility allows developers to create containerized applications without needing in-depth knowledge of the underlying Kubernetes cluster, ensuring compatibility and portability across different platforms with the help of Knative services.

Knative is compatible with all the tools, including open-source ones such as OpenFaaS and OpenWhisk, for constructing serverless applications. By leveraging these tools, you can further enhance the capabilities of your serverless applications and ensure seamless deployment and management across different platforms.

Progressive Rollouts Across Clouds

Knative’s traffic shifting features simplify the execution of progressive rollouts across various clouds. Progressive rollout in cloud computing is the method of gradually deploying new features or changes to an application or service, allowing for a controlled and phased introduction of new features to a subset of users or environments before a full deployment. This method helps reduce risks and facilitates testing and validation of changes prior to a full rollout.

In Knative, traffic shifting is accomplished by configuring the traffic spec for a service, allowing you to divide traffic among different revisions or send traffic to the most recent revision. Additionally, Knative provides a rollout-duration parameter to enable a gradual shift of traffic to the most recent revision, facilitating progressive rollouts across multiple clouds.

The Gist

We explored the power of Knative as a solution for serverless applications on Kubernetes. From its architecture and components to its advanced techniques and best practices, Knative offers a flexible and scalable platform for building, deploying, and managing modern, cloud-native applications. With Knative, you can harness the full potential of serverless computing while maintaining control and avoiding vendor lock-in. So, go ahead and embrace the future of serverless with Knative!