!env directive - References - Local Connection Configuration - User documentation for storage of Local PLC connection information in an AX workspace. - Local Connection Configuration,

The !env directive allows a user to include content from a shell environment variable. This directive accepts a single parameter, which is the name of an environment variable. With this directive, a user can dynamically pass configuration options without needing to persist them to the filesystem (e.g. CI/CD pipeline).

.ax/plcs/Plc_3.yaml

host: !env TARGET_PLC
certificate: !certificate PLC-Communication-2.pem