Docker & Kubernetes for Developers · 课时

使用 Kubernetes 实现无服务器架构（Knative）

探索 Knative 等平台如何在 Kubernetes 之上支持无服务器函数和事件驱动架构。

第 3 / 4 课11 个步骤

使用 Kubernetes 实现无服务器架构（Knative） 是 CoddyKit 上的免费 Docker & Kubernetes for Developers 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Docker & Kubernetes for Developers 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Docker & Kubernetes for Developers 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Serverless & Kubernetes

Welcome to the world of serverless on Kubernetes! Serverless computing allows you to run code without provisioning or managing servers, focusing purely on your application logic.

By combining serverless with Kubernetes, you get the benefits of both: the agility and cost-efficiency of serverless, backed by the robust, scalable, and portable infrastructure management of Kubernetes.

Knative: K8s Serverless

Knative is an open-source platform that extends Kubernetes to provide components for deploying, running, and managing serverless workloads. It simplifies the complexities of running serverless applications.

Knative has two main components: Knative Serving, which handles request-driven services, and Knative Eventing, for event-driven architectures.

Knative Serving Basics

Knative Serving is designed for deploying and managing stateless services. It takes care of:

Rapid Deployment: Quickly deploys container images.
Auto-scaling: Scales services up and down based on demand, even to zero instances when idle.
Revision Management: Provides immutable revisions for easy rollbacks and traffic splitting.

It's perfect for web applications, APIs, and microservices.

Serving: Services & Revisions

Key concepts in Knative Serving:

Service: The top-level resource, defining the desired state of your application.
Revision: An immutable snapshot of your service's code and configuration at a specific point in time. New deployments create new revisions.
Route: Manages network traffic to one or more revisions, enabling features like A/B testing or gradual rollouts.

These components work together to provide a robust deployment and scaling mechanism.

Defining a Knative Service

A Knative Service is defined using a YAML manifest, much like other Kubernetes resources. This example defines a simple 'hello-knative' service using a pre-built image.

Notice the serving.knative.dev/v1 API version and the kind: Service.

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: hello-knative
spec:
  template:
    spec:
      containers:
        - image: docker.io/knative/helloworld-go
          env:
            - name: TARGET
              value: "Knative"

Simple Serverless App

This is a basic Python Flask application that Knative would deploy. It listens for HTTP requests and responds with a greeting, using an environment variable for customization. Knative handles the containerization, deployment, and scaling of this app.

from flask import Flask
import os

app = Flask(__name__)

@app.route('/')
def hello():
    target = os.environ.get('TARGET', 'World')
    return f'Hello {target}!\n'

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8080)

Knative Eventing

Knative Eventing enables event-driven architectures on Kubernetes. It allows services to communicate asynchronously by sending and receiving events, decoupling the event producers from consumers.

This is crucial for building reactive systems that respond to various changes, like data updates, file uploads, or scheduled tasks.

Eventing: Sources & Brokers

Key components in Knative Eventing:

Event Source: Generates events from various systems (e.g., Kafka, GitHub, CronJob, S3).
Broker: A central messaging hub where event sources send events. It abstracts the underlying messaging system.
Trigger: Filters events from a Broker based on attributes and routes them to a specific event consumer (often a Knative Service).

This flow enables flexible and scalable event processing.

Example Event Flow

Imagine you have a service that processes new images. You can set up an Event Source that monitors an S3 bucket for new image uploads.

When an image is uploaded, the source sends an event to a Broker. A Trigger, configured to filter for 'new S3 image' events, then forwards that event to your image processing Knative Service.

Your service processes the image, scales down when idle, and you only pay for the compute used during processing.

Knative Knowledge Check

Which Knative component is primarily responsible for automatically scaling services up or down based on incoming requests, including scaling to zero when idle?

在交互式课程中回答

Knative Recap

In this lesson, you explored how Knative brings serverless capabilities to Kubernetes. You learned about:

Knative Serving: For deploying and auto-scaling request-driven services.
Knative Eventing: For building event-driven architectures with sources, brokers, and triggers.

Knative empowers developers to build and run serverless applications with the control and flexibility of Kubernetes.

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常见问题解答

「使用 Kubernetes 实现无服务器架构（Knative）」课时是免费的吗？

是的 — 「使用 Kubernetes 实现无服务器架构（Knative）」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Docker & Kubernetes for Developers 课程的其余内容，请升级到 CoddyKit PRO。 Docker & Kubernetes for Developers 课程共包含 4 节课。

「使用 Kubernetes 实现无服务器架构（Knative）」这节课中我会学到什么？

探索 Knative 等平台如何在 Kubernetes 之上支持无服务器函数和事件驱动架构。你通过在浏览器中直接运行的动手代码来练习 Docker & Kubernetes for Developers，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Docker & Kubernetes for Developers 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Docker & Kubernetes for Developers 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「使用 Kubernetes 实现无服务器架构（Knative）」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Docker & Kubernetes for Developers 课中编写并运行代码吗？

能。每节 Docker & Kubernetes for Developers 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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