version: 1
id: kubernetes-configmap
title: Inject Configuration with ConfigMaps
summary: Mount a ConfigMap as environment variables for a Deployment running in k3d.
difficulty: intermediate
estimatedMinutes: 35
prerequisites: [kubernetes-service]
image: alpine/k8s:1.31.4
shell: /bin/bash
runtime:
  type: k3d
setup:
  - "kubectl apply -f - <<'EOF'\napiVersion: apps/v1\nkind: Deployment\nmetadata:\n  name: api\nspec:\n  replicas: 1\n  selector:\n    matchLabels:\n      app: api\n  template:\n    metadata:\n      labels:\n        app: api\n    spec:\n      containers:\n        - name: api\n          image: nginx:1.27-alpine\n          ports:\n            - containerPort: 80\nEOF"
tasks:
  - id: configmap
    title: Wire runtime configuration
    description: Create ConfigMap api-config with LOG_LEVEL=debug, save manifests to /workspace/configmap.yaml and /workspace/deployment-patch.yaml, apply both, and ensure the api pod has LOG_LEVEL set.
    hints:
      - ConfigMap data keys become env vars via envFrom or env.valueFrom.
      - kubectl apply -f for both manifests.
    checks:
      - type: file
        name: ConfigMap manifest saved
        path: /workspace/configmap.yaml
        value: LOG_LEVEL
      - type: kubernetes
        name: ConfigMap applied
        command: kubectl get configmap api-config
      - type: kubernetes
        name: Pod has LOG_LEVEL
        command: kubectl exec deploy/api -- printenv LOG_LEVEL | grep -q debug
limits: {cpus: "1.0", memory: 512m, pids: 256, timeout: 3600, network: true}