By default, a MicroProfile Config implementation must provide three sources of configuration:
- System properties from the Java virtual machine (with an ordinal of 400)
- Environment variables (with an ordinal of 300)
- Properties stored in META-INF/microprofile-config.properties (with an ordinal of 100)
The ordinal value of a config source determines the precedence of the config source. In particular, if a property is defined both in the system properties and the environment variables, the value will be taken from the system properties (which has a higher ordinal than the environment variables).
There are no restrictions on the names of properties. However, some operating systems can impose some restrictions on the name ...