Pipe using simple language expressions causing failure

[christophd]

What happened?

When a Pipe uses a simple language expression (e.g. ${header[foo]}) to set a property value on a Kamelet (e.g. on insert-header-action Kamelet) the Pipe fails because of property resolving errors.

Many Kamelets do support simple language expressions and this includes insert-header-action Kamelet but the simple language syntax ${...} causes problems in property resolving mechanism on Camel K.

In general user defined properties on Kamelets are handled as user.properties on the Integration and the ${...} simple language expression syntax collides with the general property resolving syntax.

This issue is only when running Pipes with Camel K. Camel JBang does not report these errors.

The workaround for this is to use $simple{...} expression syntax in Pipes when using Camel K.

Steps to reproduce

Use something like this in Pipe:

    - ref:
        kind: Kamelet
        apiVersion: camel.apache.org/v1
        name: insert-header-action
      properties:
        name: kafka.OVERRIDE_TOPIC
        value: ${header[topic]}

This workaround works as expected:

    - ref:
        kind: Kamelet
        apiVersion: camel.apache.org/v1
        name: insert-header-action
      properties:
        name: kafka.OVERRIDE_TOPIC
        value: $simple{header[topic]}

Relevant log output

Caused by: java.lang.IllegalArgumentException: Property with key [value] not found in properties from text: {{value}}
	at org.apache.camel.component.properties.DefaultPropertiesParser$ParsingContext.getPropertyValue(DefaultPropertiesParser.java:369)
	at org.apache.camel.component.properties.DefaultPropertiesParser$ParsingContext.readProperty(DefaultPropertiesParser.java:232)
	at org.apache.camel.component.properties.DefaultPropertiesParser$ParsingContext.doParseNested(DefaultPropertiesParser.java:169)
	at org.apache.camel.component.properties.DefaultPropertiesParser$ParsingContext.parse(DefaultPropertiesParser.java:118)
	at org.apache.camel.component.properties.DefaultPropertiesParser.parseUri(DefaultPropertiesParser.java:70)
	at org.apache.camel.component.properties.PropertiesComponent.parseUri(PropertiesComponent.java:315)
	at org.apache.camel.component.properties.PropertiesComponent.parseUri(PropertiesComponent.java:170)
	at org.apache.camel.impl.engine.DefaultCamelContextExtension.resolvePropertyPlaceholders(DefaultCamelContextExtension.java:230)
	at org.apache.camel.impl.engine.AbstractCamelContext.resolvePropertyPlaceholders(AbstractCamelContext.java:1566)
	at org.apache.camel.support.CamelContextHelper.parseText(CamelContextHelper.java:374)
	at org.apache.camel.reifier.AbstractReifier.parseString(AbstractReifier.java:58)
	at org.apache.camel.reifier.language.ExpressionReifier.createExpression(ExpressionReifier.java:161)
	at org.apache.camel.reifier.AbstractReifier.createExpression(AbstractReifier.java:119)
	at org.apache.camel.reifier.SetBodyReifier.createProcessor(SetBodyReifier.java:34)
	at org.apache.camel.reifier.ProcessorReifier.makeProcessor(ProcessorReifier.java:853)
	at org.apache.camel.reifier.ProcessorReifier.addRoutes(ProcessorReifier.java:593)
	at org.apache.camel.reifier.RouteReifier.doCreateRoute(RouteReifier.java:213)

### Camel K version

2.0.1

[squakez]

I think this is due to #4618 - we need to let Camel framework to manage Kamelets OOTB, with its internal mechanism of replacements, loading, etc... while working on that one, we can make sure also this issue is addressed.

[gansheer]

Out of curiosity, heve you tried something like $${header[topic]} or \\${header[topic]} ?

[squakez]

Not a bug. This is a side effect of the need to provide a placeholder in the route which will be later resolved with a configuration property. We should understand the mechanism replacement adopted by JBang and try to mimick it if that is feasible.

[christophd]

@squakez how could this not be a bug? ${header[topic]} is a fully valid simple language expression in Camel. Users do not care about how Camel K internally uses configuration property replacement.

Anyway, as you said, we need to see how JBang runtime does it and fix/add support for this simple language expressions when using Pipes in Camel K

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