Allow lazy loading of the data sources

[ikovalyov]

We don't need to load datasources in our web app, or tests. We need it only if app is loaded from the command line. Unfortunately there is no way to do a lazy loading of the datasources as it is annotated with @Context

[dstepanov]

You should probably have a different profile where data-sources properties are only provided in the command line profile.

[sdelamo]

@ikovalyov

what you could do is to move the datasources block to a configuration file such as application-cli.yml.

Then it would not be loaded unless you run with environments such as cli

[nhoughto]

Would love this, causing a bit of pain atm with shared/inherited config, where datasource config is specified at a higher level and this triggers downstream components to try and construct the Datasource where i'd like them not to.

I believe the idiomatic micronaut way to do this is to support io.micronaut.core.util.Toggleable and then configure the data source as enabled: false at a higher level, and then enabled: true at the lower level. Lots of other areas/configurations support this Toggleable but not Datasource.