KCNA Kubernetes Fundamentals Practice Question
Which TWO of the following are valid ways to expose environment variables from a ConfigMap to a pod?
⚠ Common exam trap
CNCF often tests the distinction between `configMapKeyRef` and `secretKeyRef`, expecting candidates to know that `secretKeyRef` is for Secrets only, not ConfigMaps, and that `env.value` is for static values, not dynamic references.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
env.valueFrom.configMapKeyRef
Environment variables from a ConfigMap can be exposed to a pod using envFrom to inject all key-value pairs as environment variables, or using env.valueFrom.configMapKeyRef to inject a specific key as an environment variable. Using volumes and volumeMounts mounts the ConfigMap as files in the filesystem, not as environment variables. Option B (env.value) is for static values, not references. Option C (secretKeyRef) is for Secrets, not ConfigMaps.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
volumes and volumeMounts
Why it's wrong here
Volumes and volumeMounts expose ConfigMap data as files in the filesystem, not as environment variables. This method does not satisfy the requirement for exposing environment variables.
- ✗
env.value
Why it's wrong here
env.value is for static values, not dynamic references to ConfigMaps.
- ✗
env.valueFrom.secretKeyRef
Why it's wrong here
secretKeyRef is for referencing Secrets, not ConfigMaps. ConfigMaps use configMapKeyRef.
- ✓
env.valueFrom.configMapKeyRef
Why this is correct
Correct. env.valueFrom.configMapKeyRef allows referencing a specific key from a ConfigMap and exposing it as an environment variable.
- ✓
envFrom
Why this is correct
Correct. envFrom allows injecting all key-value pairs from a ConfigMap as environment variables.
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