ConfigMaps¶

A ConfigMap is a Kubernetes object used to store non-sensitive configuration data.

ConfigMaps allow applications to receive configuration values without modifying the container image.

This enables the same container image to run in multiple environments while using different configuration settings.

What ConfigMaps Store¶

ConfigMaps store configuration as key-value pairs.

Examples of configuration stored in ConfigMaps include:

application settings
configuration files
feature flags
environment-specific values
service endpoints

Example structure:

APP_ENV=production LOG_LEVEL=info API_URL=https://api.example.com

These values are stored in Kubernetes and can be referenced by pods when containers start.

Why ConfigMaps Exist¶

Container images should ideally be immutable.

This means an image should not change once it has been built.

However, applications often require configuration that changes between environments.

For example:

Environment	Database
Development	dev-db
Staging	staging-db
Production	prod-db

Instead of building three different images, Kubernetes allows configuration to be provided dynamically using ConfigMaps.

How Applications Use ConfigMaps¶

Pods can consume ConfigMaps in several ways.

Method	Description
Environment Variables	Inject configuration values into containers
Command Arguments	Pass configuration to startup commands
Mounted Files	Provide configuration files inside containers

This flexibility allows applications to receive configuration in whatever format they expect.

ConfigMaps and Pods¶

Pods reference ConfigMaps when they start.

The configuration values are then injected into the containers.

ConfigMap Injection

flowchart TD ConfigMap["ConfigMap (app-config)"] Pod["Pod"] Container["Application Container"] ConfigMap --> Pod Pod --> Container

In this example:

Configuration values are stored in a ConfigMap.
The pod references the ConfigMap.
The container receives the configuration values.

When to Use ConfigMaps¶

ConfigMaps should be used for non-sensitive configuration.

Typical use cases include:

application settings
feature flags
configuration files
environment configuration
service URLs

When Not to Use ConfigMaps¶

ConfigMaps should not be used for sensitive information.

Examples of sensitive data include:

passwords
API tokens
private keys
database credentials

Sensitive information should be stored using Secrets instead.

Key Takeaway¶

ConfigMaps allow applications to receive environment-specific configuration without modifying container images, making deployments more flexible and maintainable.

Next¶

The next page explores Secrets, which are used for storing sensitive configuration data.