A ConfigMap holds several keys, but the app only needs app.properties as one file inside an existing config directory that already has other files. What should the volumeMount use?
Select an answer to reveal the explanation.
Short Explanation
Dropping a whole ConfigMap volume on a folder is like dumping a moving box on a tidy desk—it covers everything. subPath is the “place just this one sheet” trick: one key lands as one file and the rest of the directory stays put.
Full Explanation
A normal ConfigMap volume mount replaces the contents of the mount path with the projected keys. Using volumeMounts.subPath (or the matching key name) mounts a single file into an existing directory without clobbering sibling files. envFrom injects environment variables and does not solve the single-file mount case.