CKA Workloads and Scheduling Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Using volumeMounts with configMapKeyRef

  Why it's wrong here

  volumeMounts mounts a volume into the container's filesystem, not into the environment. configMapKeyRef is a valid field only inside valueFrom of an env entry, where it selects a specific key from a ConfigMap to set an environment variable. Using configMapKeyRef in volumeMounts is invalid because volumeMounts expects the name of an existing volume that you have separately defined in the volumes list. To get files from a ConfigMap, you create a volume of type configMap and then volumeMount it by that volume's name.

• ✗

  Using env with configMapRef

  Why it's wrong here

  In a container's env list, configMapRef is not a valid field for injecting a ConfigMap directly. The correct place for configMapRef is inside envFrom, which imports all keys from a ConfigMap as environment variables in one go. For injecting a single key as an environment variable, you must use env with valueFrom.configMapKeyRef instead. Attempting to write 'configMapRef' under an env entry would fail schema validation because env entries only support name and value or valueFrom.

• ✓

  Using env with valueFrom.configMapKeyRef

  Why this is correct

  This is the precise way to inject a single key from a ConfigMap into a single environment variable. The env entry defines the environment variable's name, and valueFrom.configMapKeyRef specifies the ConfigMap name and the exact key to pull the value from. It gives you fine-grained control over which keys get exposed and what they are called in the environment, unlike envFrom which blindly imports all keys. You can also add an optional 'optional' field to make the resource not fail if the key is missing.

• ✓

  Using envFrom with configMapRef

  Why this is correct

  envFrom with configMapRef correctly injects all keys from a ConfigMap as environment variables at once. Each key in the ConfigMap becomes an environment variable whose name is the key itself and whose value is the corresponding value. This is the bulk injection method, useful when you want the entire configuration applied without enumerating individual env entries. However, be aware that keys that are not valid environment variable names (e.g., containing hyphens or dots) may be skipped or cause the container to fail depending on the Kubernetes version and 'optional' settings.

• ✗

  Using volumes with configMap

  Why it's wrong here

  A volume of type configMap mounts the ConfigMap's data as files inside the container's filesystem, not as environment variables. Each key becomes a filename and each value becomes the file's content. This is the standard approach for providing configuration files such as application properties or server configs, but it does not inject anything into the environment. If you need environment variables, you must use env or envFrom instead of creating a volume.

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