ConfigMaps let you decouple configuration artifacts from image content, so containerized applications are easily portable. With ConfigMaps you can store configuration data in key–value pairs and inject them into Pods as environment variables or mounted files.
ConfigMaps are not designed for sensitive information. Use Secrets for credentials and tokens. Why Use ConfigMaps? Hard-coding environment variables in Pod specs is tedious when you maintain multiple workloads. Consider this example:
apiVersion : v1 kind : Pod metadata : name : simple-webapp-color spec : containers : - name : simple-webapp-color image : simple-webapp-color ports : - containerPort : 80 env : - name : APP_COLOR value : blue - name : APP_MODE value : prod
Updating dozens of Pod definitions manually increases the risk of misconfiguration. Instead, extract these values into a single ConfigMap.
ConfigMap Lifecycle
Create a ConfigMapInject it into your Pod
1. Creating a ConfigMap Kubernetes supports both imperative and declarative creation methods.
Imperative (kubectl) Approach From literal key–value pairs:
kubectl create configmap app-config \ --from-literal=APP_COLOR=blue \ --from-literal=APP_MODE=prod
From a properties file (each file entry becomes a key):
kubectl create configmap app-config \ --from-file=app_config.properties
Declarative (YAML) Approach Define config-map.yaml:
apiVersion : v1 kind : ConfigMap metadata : name : app-config data : APP_COLOR : blue APP_MODE : prod
Apply the configuration:
kubectl apply -f config-map.yaml
Use descriptive names and labels for each ConfigMap (e.g., app-config, mysql-config, redis-config) so you can manage them easily across environments.
Inspecting ConfigMaps List all ConfigMaps:
Describe a specific ConfigMap:
kubectl describe configmap app-config
Sample output:
Name: app-config Namespace: default Data ==== APP_COLOR: blue APP_MODE: prod
2. Injecting ConfigMaps into Pods You can consume ConfigMaps in two main ways:
As environment variables
As files via a mounted volume
A. Environment Variables Bulk Injection with envFrom
Inject all keys as environment variables:
apiVersion : v1 kind : Pod metadata : name : simple-webapp-color spec : containers : - name : simple-webapp-color image : simple-webapp-color ports : - containerPort : 80 envFrom : - configMapRef : name : app-config
Single Key Injection
Inject a specific key:
apiVersion : v1 kind : Pod metadata : name : simple-webapp-color spec : containers : - name : simple-webapp-color image : simple-webapp-color ports : - containerPort : 80 env : - name : APP_COLOR valueFrom : configMapKeyRef : name : app-config key : APP_COLOR
B. File-based Injection Mount ConfigMap entries as files inside the container:
apiVersion : v1 kind : Pod metadata : name : simple-webapp-with-files spec : containers : - name : simple-webapp image : simple-webapp volumeMounts : - name : config-volume mountPath : /etc/config volumes : - name : config-volume configMap : name : app-config
Each key in app-config appears as a separate file in /etc/config.
Comparing Injection Methods Injection Type Use Case Configuration Option Bulk environment loading Simple, all-in-one injection envFrom.configMapRefSingle variable reference Granular control per key env.valueFrom.configMapKeyRefFile mounting Applications reading configs as files volumes.configMap
Further Reading References 
