camel-kamelet: improve global properties handling

[lburgazzoli]

The way the kamelet component handles properties as today is:

camel.kamelet.${templateId}
camel.kamelet.${templateId}.${routeId}

But there are some issue with that:

1. the routeId may be confusing as it can be used for setting a template property and as a root for the materialized route properties
2. it uses a non standard prefix as all the component use camel.component.${scheme}

A possible alternative is to to leverage camel's capabilities to use map, something like:

camel.component.kamelet.template-properties[${templateId}][foo] = bar
camel.component.kamelet.route-properties[${routeId}][foo] = bar

However it looks quite ugly, a better option would be:

camel.component.kamelet.template-properties[${templateId}].foo = bar
camel.component.kamelet.route-properties[${routeId}].foo = bar

But I don't think camel is currently able to handle this case so we should probably enhance the properties binding support, as example we can mark a component to be PropertiesAware so the binding process should not try to bind the entire object tree but it delegates the mapping to the receiver object.

public interface PropertiesAware {
    void setProperties(Map<String, String> properties);
    Map<String, String> properties getProperties(Map<String, String> properties);
}

Assuming the component would have been something like:

public class KameletComponent extends DefaultComponent {
    private Map<String, PropertiesHolder> templateProperties;
    private Map<String, PropertiesHolder> routeProperties;

    // getter/Setter omitted
}

public class PropertiesHolder implements PropertiesAware {
    @Override
    public void setProperties(Map<String, String> properties) { ... }
    @Override
    public Map<String, String> properties getProperties(Map<String, String> properties) { ... }
}

The binding process then can stop at camel.component.kamelet.template-properties[${templateId}] and camel.component.kamelet.route-properties[${routeId}] and any further processing should be eventually done by the receiver.

@davsclaus does this make any sense ?
@nicolaferraro would the new format be problematic for the operator ? (we'll keep the old way for some time in any case)

[davsclaus]

On top of my head there is some components that have property prefix, like camel-http with http client options
https://github.com/apache/camel/blob/master/components/camel-http/src/main/java/org/apache/camel/component/http/HttpComponent.java#L406

(mind that the http component is one of the more complex component for this kind) I think rabbitmq and some others have a bit simpler code for this option prefix options.

Maybe we could have something like that, then its

camel.component.kamelet.template-properties.myTemplate.foo = bar
camel.component.kamelet.template-properties.myTemplate.code = 1234
camel.component.kamelet.route-properties.myRoute.foo = bar

Then template-properties and route-properties are just a Map which we then use that extract code (see link above) and in the kamelet component we can then do the binding we want.

[lburgazzoli]

oh, that's cool and yes that would do what I'm looking for

[lburgazzoli]

@davsclaus do you think we can have something for this in 3.7 ?

[davsclaus]

Yeah have you tried that extract property thingy? And if so then there should likely only need code changes in camel-kamelet component and not in core camel

[lburgazzoli]

not yet

[davsclaus]

Okay if you dont find the time and when I get the compiled simple done, then I can take a look

[lburgazzoli]

Ok, so after we get CAMEL-15886, CAMEL-15887 solved and we get camel 3.7 out then we can get this working. At the moment we can use camel.component.kamelet.configuration.template-properties[myTemplate].foo

[lburgazzoli]

Fixed by #573