Enhancement request: system property substitution in resource files

[giamma]

When defining a datasource in a property file, or possibly any other supported resource, it would be great to be able to use system property substitution, e.g.

dataSource.serverName=${database.name}

This could be especially convenient for docker images or for quickly relocating the database server or also for passwords, which could be exported in the environment rather than being written in the file.

[h-thurow]

See JNDIConfigurationTest#dotDelimitedSharedAndVariableInterpolation()

[h-thurow]

Okay, I see. My last comment is not helpful when defining a datasource, because when the datasource is created by Simple-JNDI properties are not read with JNDIConfiguration.

[h-thurow]

From just released 0.19.0 on values can reference system properties. To be interpolated they must be in the form

${sj.sys:name_of_system_property}

See SJPropertiesSubstitutionTest.