ConfigMaps and Secrets Flashcards

Which kubectl command creates a ConfigMap named 'app-config' with a literal key-value pair 'ENV=production'?

Answer: kubectl create configmap app-config --from-literal=ENV=production

The --from-literal flag is the correct way to pass key=value pairs directly on the command line when creating a ConfigMap.

How do you expose all key-value pairs from a ConfigMap named 'app-config' as environment variables in a Pod?

Answer: Use envFrom with configMapRef specifying the ConfigMap name

The envFrom field with configMapRef injects all ConfigMap keys as environment variables at once, without listing them individually.

A ConfigMap is mounted as a volume in a Pod. After the ConfigMap is updated, what happens to the files inside the running Pod?

Answer: The files are eventually updated automatically by the kubelet

When a ConfigMap is mounted as a volume, the kubelet periodically syncs the projected files, so changes propagate eventually without a Pod restart.

Which kubectl command creates a ConfigMap from all files in a directory named 'configs/'?

Answer: kubectl create configmap my-config --from-file=configs/

The --from-file flag accepts either a single file path or a directory path; when given a directory, it creates one key per file.

What is the maximum data size allowed in a single Kubernetes ConfigMap?

Answer: 1 MiB

Kubernetes enforces a 1 MiB (1,048,576 byte) limit on ConfigMap data to avoid overwhelming the etcd storage backend.

How do you reference a single key 'DB_HOST' from a ConfigMap named 'db-config' as an environment variable in a container?

Answer: Use env with valueFrom.configMapKeyRef specifying the ConfigMap name and key

To inject a specific key from a ConfigMap as an env var, use the env field with valueFrom.configMapKeyRef referencing the name and key.

What field do you set on a ConfigMap to prevent any future modifications to its data?

Answer: immutable: true

Setting immutable: true on a ConfigMap prevents any updates to its data or binaryData fields, which also improves performance by eliminating watch overhead.