frontend

KCP Frontend

React + TypeScript frontend for the KCP web UI.

Development

Prerequisites

• Node.js 18+
• Yarn

Setup

yarn install

Development Server

yarn dev

Frontend runs on http://localhost:5173 with hot reload.

Build

yarn build

Built assets are embedded into the Go binary via frontend.go.

Type Checking

yarn type-check
yarn type-check:watch

Linting

yarn lint

Testing

E2E Tests with Playwright

Playwright tests run against the full Go backend + frontend.

Run all tests:

yarn test:e2e

Run with UI mode (interactive):

yarn test:e2e:ui

Debug specific test:

yarn test:e2e:debug osk-sidebar.spec.ts

Run with browser visible:

yarn test:e2e:headed

Test Fixtures

Test fixtures are in tests/fixtures/:

• state-osk-only.json - Apache Kafka clusters only
• state-both.json - Both MSK and Apache Kafka clusters

Architecture

Source Types

The UI supports two Kafka source types:

MSK (AWS Managed Streaming for Kafka)

• Regions → Clusters hierarchy
• Displays: ARN, VPC, instance type, CloudWatch metrics, costs
• Tabs: Cluster, Metrics, Topics, ACLs, Connectors, Clients

Apache Kafka

• Flat cluster list
• Displays: Bootstrap servers, metadata, labels
• Tabs: Cluster, Topics, ACLs, Connectors, Clients (no Metrics)

State Management

• Zustand for global state
• useAppStore hook provides access to:
  • processedState - unified source data
  • selectedSourceType - 'msk' | 'osk'
  • selectOSKCluster(clusterId) - navigate to Apache Kafka cluster
  • selectCluster(region, arn) - navigate to MSK cluster

Type Guards

Use type guards from lib/sourceUtils.ts to safely access source-specific data:

import { isMSKSource, isOSKSource } from '@/lib/sourceUtils'

const mskSource = processedState?.sources.find(isMSKSource)
const oskSource = processedState?.sources.find(isOSKSource)

Tech Stack

• React 19
• TypeScript 5.8
• Vite 7
• Zustand (state management)
• Recharts (charts)
• Tailwind CSS 4
• Playwright (E2E testing)