Kubernetes Configuration

Generate Kubernetes manifests for multiple environments (prod/staging/dev) from a single JSSON template with environment-specific configurations.

The Problem

Managing Kubernetes configs across environments means:

• Duplicate manifests — Separate YAML/JSON files for each environment
• Inconsistent naming — Easy to make mistakes in resource names
• Hard to update — Changes require editing multiple files
• Error-prone — Copy-paste errors in similar configs

The JSSON Solution

One template generates configs for all environments with conditional logic!

JSSON

deployments [
template { appName, env, replicas }

map (deploy) = {
  apiVersion = "apps/v1"
  kind = "Deployment"
  name = deploy.appName + "-" + deploy.env
  namespace = deploy.env
  replicas = deploy.replicas

  // Environment-specific image tag
  image = "registry/" + deploy.appName + ":" + (deploy.env == "prod" ? "stable" : "latest")

  // Environment-specific resources
  memoryRequest = deploy.env == "prod" ? "512Mi" : "256Mi"
  cpuRequest = deploy.env == "prod" ? "500m" : "250m"
  memoryLimit = deploy.env == "prod" ? "1Gi" : "512Mi"
  cpuLimit = deploy.env == "prod" ? "1000m" : "500m"

  // Environment variables
  environment = deploy.env
  logLevel = deploy.env == "prod" ? "error" : "debug"
}

// Production: high replicas
"api", "prod", 5
"web", "prod", 3

// Staging: medium replicas
"api", "staging", 2
"web", "staging", 2

// Development: minimal replicas
"api", "dev", 1
"web", "dev", 1
]

JSON Output

{
"deployments": [
  {
    "apiVersion": "apps/v1",
    "kind": "Deployment",
    "name": "api-prod",
    "namespace": "prod",
    "replicas": 5,
    "image": "registry/api:stable",
    "memoryRequest": "512Mi",
    "cpuRequest": "500m",
    "memoryLimit": "1Gi",
    "cpuLimit": "1000m",
    "environment": "prod",
    "logLevel": "error"
  },
  {
    "apiVersion": "apps/v1",
    "kind": "Deployment",
    "name": "web-prod",
    "namespace": "prod",
    "replicas": 3,
    "image": "registry/web:stable"
    // ... more fields
  }
  // ... 4 more deployments
]
}

Key Features Used

Conditional Logic

// Different image tags per environment
image = "registry/" + deploy.appName + ":" + (deploy.env == "prod" ? "stable" : "latest")

// Different resources per environment
memoryRequest = deploy.env == "prod" ? "512Mi" : "256Mi"

String Concatenation

// Consistent naming convention
name = deploy.appName + "-" + deploy.env
// Results in: "api-prod", "web-staging", etc.

Templates for Structure

template { appName, env, replicas }

// Define once, use for all apps and environments
"api", "prod", 5
"web", "staging", 2

Services Configuration

services [
template { appName, env, port }

map (svc) = {
  apiVersion = "v1"
  kind = "Service"
  name = svc.appName + "-" + svc.env
  namespace = svc.env
  type = svc.env == "prod" ? "LoadBalancer" : "ClusterIP"
  port = svc.port
  targetPort = svc.port
  protocol = "TCP"
}

"api", "prod", 8080
"web", "prod", 3000
"api", "staging", 8080
"web", "staging", 3000
]

ConfigMaps

configMaps [
template { env }

map (cfg) = {
  apiVersion = "v1"
  kind = "ConfigMap"
  name = "app-config-" + cfg.env
  namespace = cfg.env
  databaseHost = "postgres-" + cfg.env + ".internal"
  redisHost = "redis-" + cfg.env + ".internal"
  cacheTTL = cfg.env == "prod" ? "3600" : "60"
  featureFlags = cfg.env == "prod" ? "stable" : "experimental"
}

"prod"
"staging"
"dev"
]

Benefits

Consistency — Same naming conventions across all resources
DRY — Define once, generate for all environments
Type Safety — Templates ensure all required fields are present
Easy Updates — Change one template, update all environments
Less Error-Prone — No copy-paste mistakes

When to Use This Pattern

Perfect for:

• Multi-environment Kubernetes deployments
• Microservices with similar configs
• Infrastructure as code
• Helm chart alternatives
• GitOps workflows

Not ideal for:

• Extremely different configs per environment
• One-off, unique resources
• Complex Helm chart replacements

Try It Yourself!

1. Save the deployments example to k8s.jsson
2. Run: jsson -i k8s.jsson -o k8s.json
3. Use the JSON to generate Kubernetes manifests!

What’s Next?

• API Gateway — Microservices routing
• Feature Flags — Environment configs
• Overview — See all examples

One template, all environments! ☸️