Knative Official Documentation

Knative provides Kubernetes-based building blocks that matter most to developers. Built on Kubernetes APIs, Knative streamlines serverless application development and delivery.

What is Knative?

Knative is a Kubernetes-based framework for building, deploying, and managing modern serverless workloads. It provides standardized, platform-agnostic components that enable developers to focus on business logic rather than infrastructure complexity.

Core Components

Knative is composed of three primary modules, each solving a critical cloud-native challenge:

Architecture Overview

Knative extends Kubernetes through Custom Resource Definitions (CRDs) and controllers that reconcile desired state. The architecture follows a control-plane/data-plane separation:

• Control Plane: Controllers watch for Service, Revision, and Configuration resources, generating underlying Deployments, Services, and Routes.
• Data Plane: The net-istio or net-kourier ingress controllers handle traffic routing, TLS termination, and request distribution.
• Autoscaler: The autoscaler-hpa or kpa (Knative Pod Autoscaler) monitors request concurrency and CPU/memory metrics to scale pods.

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: helloworld-go
  namespace: default
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-samples/helloworld-go
          env:
            - name: TARGET
              value: "World"
      containerConcurrency: 10

Installation

Knative can be installed via kn CLI, ko, or kubectl apply. The recommended production approach uses the official YAML manifests or Helm charts.

kubectl apply --filename https://github.com/knative/serving/releases/download/knative-v1.12.0/serving-crds.yaml
kubectl apply --filename https://github.com/knative/serving/releases/download/knative-v1.12.0/serving-core.yaml
kubectl apply --filename https://github.com/knative/net-istio/releases/download/knative-v1.12.0/istio.yaml

Knative Serving Deep Dive

Knative Serving abstracts Kubernetes Deployments behind the Service API. Each Service creates a Configuration, which spawns Revisions. Traffic is routed through a Route and Configuration object.

Revision Strategy

Revisions are immutable snapshots of your application. This enables safe rollouts, canary deployments, and instant rollbacks without downtime.

• Active Revision: Currently receiving traffic
• Latest Revision: Most recently created, not necessarily receiving traffic
• Ready Revision: Passes health checks and is eligible for routing

Eventing Fundamentals

Knative Eventing provides a cloud-native, declarative eventing platform. It adheres to the CloudEvents specification and enables loose coupling between producers and consumers.

Broker & Trigger Model

The Broker/Trigger model is the recommended pattern for production workloads. Brokers aggregate events from multiple sources, while Triggers filter and route events to specific subscribers.

apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: default
---
apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  name: order-processor
spec:
  broker: default
  filter:
    attributes:
      type: dev.knative.source.order.created
  subscriber:
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: order-service

Next Steps