Creating ConfigMaps

ConfigMaps store non-sensitive configuration data as key-value pairs. They decouple configuration from container images, letting you change settings without rebuilding or redeploying.

From Literal Values

Create a ConfigMap directly from command-line key-value pairs:

kubectl create configmap app-config \
  --from-literal=DATABASE_HOST=postgres \
  --from-literal=DATABASE_PORT=5432 \
  --from-literal=LOG_LEVEL=info

From a File

Store an entire file as a ConfigMap entry. The filename becomes the key:

# Single file
kubectl create configmap nginx-config --from-file=nginx.conf

# Custom key name
kubectl create configmap nginx-config --from-file=default.conf=nginx.conf

# Entire directory
kubectl create configmap config-dir --from-file=./config/

From an Env File

Load key-value pairs from a .env-style file:

# app.env contains: KEY=value (one per line)
kubectl create configmap app-config --from-env-file=app.env

Unlike --from-file, this creates individual keys for each line rather than storing the file as a single entry.

YAML Definition

Define a ConfigMap declaratively for version control:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
  namespace: default
data:
  DATABASE_HOST: postgres
  DATABASE_PORT: "5432"
  LOG_LEVEL: info
  app.properties: |
    server.port=8080
    server.context-path=/api
    feature.cache.enabled=true

Apply it with:

kubectl apply -f configmap.yaml

Verifying

kubectl get configmap app-config
kubectl describe configmap app-config
kubectl get configmap app-config -o yaml

All values in a ConfigMap are stored as strings. Numeric values like port numbers must be quoted in YAML definitions.