The agent needs to derive its own identity from several aspects of the underlying OS. In order to do so, at startup it performs run-time introspection of current machine state and OS metadata.
The following details are derived from the host environment:
- application-specific node UUID
- base architecture
- update stream
- OS platform
- OS version
- OSTree revision
It is thus required that the OS provides those values in the locations described below.
Kernel command-line must contain a
ignition.platform.id=<VALUE> argument. The literal value is used as the “OS platform”.
Booted deployment must provide several mandatory metadata entries:
checksum: OSTree commit revision
version: OS version
coreos-assembler.basearch: base architecture
fedora-coreos.stream: update stream
All those metadata entries must exist with a non-empty string value.
Filesystem must provide a
/etc/machine-id file, as specified by machine-id spec. Its value is used to derive the application-specific node UUID.