Kubernetes config maps and secrets allow use to inject configuration files into containers. If we want multiple config entries that originate from different config maps or secrets to be injected into the same location, we are required to specify a sub path:<\/p>\n
kind: Deployment\r\napiVersion: apps\/v1\r\nmetadata:\r\n name: hello-world\r\nspec:\r\n replicas: 1\r\n template:\r\n metadata:\r\n labels:\r\n app: hello-world\r\n spec:\r\n containers:\r\n - name: hello-world\r\n image: docker.example.com\/app:1\r\n volumeMounts:\r\n - name: hello-world-config-volume\r\n mountPath: \/config\/application.properties\r\n subPath: application.properties\r\n readOnly: true\r\n - name: hello-world-credentials-volume\r\n mountPath: \/config\/credentials.properties\r\n subPath: credentials.properties\r\n readOnly: true\r\n volumes:\r\n - name: hello-world-config-volume\r\n configMap:\r\n name: hello-world-config\r\n - name: hello-world-credentials-volume\r\n secret:\r\n secretName: hello-world-credentials<\/pre>\nThis example will create two volumes from the contents of the config map
hello-world-config<\/code> and the secrethello-world-credentials<\/code>.<\/p>\nImagine, these resources have the following contents:<\/p>\n
kind: ConfigMap\r\napiVersion: v1\r\nmetadata:\r\n name: hello-world-config\r\ndata:\r\n application.properties: |\r\n greeting=Hello\r\n name=World\r\n\r\n---\r\n\r\nkind: Secret\r\napiVersion: v1\r\nmetadata:\r\n name: hello-world-credentials\r\ndata:\r\n credentials.properties: <base64>\r\ntype: Opaque<\/pre>\nThe example will mount the file contents of the key
application.properties<\/code> of the config map to a file with the same name under\/config\/<\/code> and will mount the secret valuecredentials.properties<\/code> as the second file under that directory. The application will be able to access both files read-only.<\/p>\nThe
subPath<\/code> declaration also allows to mount a single volume into the pod multiple times with different sub paths.<\/p>\n\n