nodes-containers-downward-api-about.adoc

Expose Pod information to Containers using the Downward API

The Downward API contains such information as the pod’s name, project, and resource values. Containers can consume information from the downward API using environment variables or a volume plug-in.

Fields within the pod are selected using the FieldRef API type. FieldRef has two fields:

Field	Description
fieldPath	The path of the field to select, relative to the pod.
apiVersion	The API version to interpret the fieldPath selector within.

Currently, the valid selectors in the v1 API include:

Selector	Description
metadata.name	The pod’s name. This is supported in both environment variables and volumes.
metadata.namespace	The pod’s namespace.This is supported in both environment variables and volumes.
metadata.labels	The pod’s labels. This is only supported in volumes and not in environment variables.
metadata.annotations	The pod’s annotations. This is only supported in volumes and not in environment variables.
status.podIP	The pod’s IP. This is only supported in environment variables and not volumes.

The apiVersion field, if not specified, defaults to the API version of the enclosing pod template.