Database + App

Cross-resource references for database connection strings.

Complete Example

import { type } from 'arktype';
import { kubernetesComposition } from 'typekro';
import { Deployment, Service, Secret } from 'typekro/simple';

const FullStackSpec = type({ 
  name: 'string', 
  appImage: 'string', 
  replicas: 'number' 
});

const FullStackStatus = type({ 
  ready: 'boolean', 
  dbReady: 'boolean', 
  appReady: 'boolean' 
});

export const fullstack = kubernetesComposition({
  name: 'fullstack',
  apiVersion: 'example.com/v1alpha1',
  kind: 'FullStack',
  spec: FullStackSpec,
  status: FullStackStatus,
}, (spec) => {
  Secret({ 
    id: 'dbSecret', 
    name: `${spec.name}-db-secret`, 
    stringData: { password: 'secret123' } 
  });

  const db = Deployment({
    id: 'db',
    name: `${spec.name}-db`,
    image: 'postgres:15',
    ports: [{ containerPort: 5432 }],
    env: { POSTGRES_PASSWORD: 'secret123', POSTGRES_DB: spec.name }
  });

  const dbSvc = Service({
    id: 'dbSvc',
    name: `${spec.name}-db-svc`,
    selector: { app: `${spec.name}-db` },
    ports: [{ port: 5432, targetPort: 5432 }]
  });

  const app = Deployment({
    id: 'app',
    name: spec.name,
    image: spec.appImage,
    replicas: spec.replicas,
    ports: [{ containerPort: 3000 }],
    env: {
      DATABASE_HOST: dbSvc.status.clusterIP,  // ✨ Cross-resource reference
      DATABASE_URL: `postgresql://postgres:secret123@${spec.name}-db-svc:5432/${spec.name}`
    }
  });

  return {
    ready: db.status.readyReplicas > 0 && app.status.readyReplicas >= spec.replicas,
    dbReady: db.status.readyReplicas > 0,
    appReady: app.status.readyReplicas >= spec.replicas
  };
});

Deploy

const factory = fullstack.factory('direct', { namespace: 'dev' });
await factory.deploy({ name: 'myapp', appImage: 'node:20', replicas: 2 });

Key Concepts

• Cross-resource references: dbSvc.status.clusterIP references the database service's runtime IP
• Service discovery: App connects to database via service name
• Status aggregation: Overall readiness depends on both database and app
• Template literals: Dynamic connection strings with `${spec.name}`
• Resource IDs: Every resource that's referenced (in status or from other resources) has an id

When is id optional?

The Secret in this example has id: 'dbSecret' but it's not referenced anywhere. You could omit it, but including id on all resources is good practice for consistency and future-proofing.

Next Steps

• Helm Integration - Use Helm charts for databases
• Multi-Environment - Environment-specific configs