The plugin configuration belongs in @PLUGIN@.config. The credentialsPath is required when not using the Spanner emulator.

[ref-database "spanner"]
        instance = spanner-instance
        database = global-refdb
        useEmulator = false
        credentialsPath = /path/to/credentials.json

ref-database.spanner.instance : Optional. The name of the spanner instance. Default: spanner-instance.

ref-database.spanner.database : Optional. The name of the spanner database. Default: global-refdb.

ref-database.spanner.useEmulator : Optional. Boolean, whether or not to use the in-memory Cloud Spanner emulator. Default: false.

ref-database.spanner.credentialsPath : Required when not using the emulator. The path to Google cloud credentials. Default: null.