NIFI-5777: Update the tag and the property of LogMessage

[kotarot]

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[pvillard31]

I disagree with this change: disabling the expression usage validation should be avoided as much as possible and, if I recall correctly, is only necessary in very specific edge cases. Instead of disabling the validation, I'd fix the original issue by removing .evaluateAttributeExpressions(flowFile) on L129 in LogMessage since it does not make sense. Once it's fixed, I'm a +1 and can merge to master. Feel free to squash your commits. Thanks!

[ijokarumawak]

Hmm, I think changing logLevel based on expression makes sense. For example, if you want to debug for a particular type of FlowFiles, you'd use EL to write WARN level log for specific attribute value and use TRACE/DEBUG for others to minimize the noise. I don't think specifying log level by text is a critical issue..

[pvillard31]

In that case I'm not sure to understand the intent of this PR. Initially I thought it was about removing .expressionLanguageSupported(ExpressionLanguageScope.FLOWFILE_ATTRIBUTES) on LOG_LEVEL since the property only accepts a list of allowed values. If we do that, then we should remove the .evaluateAttributeExpressions(flowFile), no?

On the other hand, if we do want to allow EL on this property, then the property and code should be changed to allow free text value that is validated against the list of allowed values only if EL is not used. And then if EL is used, there should be a default behavior in case the value, after EL evaluation, is not an allowed value.

Am I missing something?

[ijokarumawak]

Sorry for the confusion. I was just looking at the source code. When I run the processor, I realized that the processor doesn't allow EL. The logLevel is shown as a free text input, and I can input EL, but validation failed because of the configured allowable values.

I still think changing log level by EL would be nice:

My suggestion is, changing:

            .description("The Log Level to use when logging the message")
            .allowableValues(MessageLogLevel.values())

to

            .description("The Log Level to use when logging the message: " + Arrays.toString(MessageLogLevel.values()))
            .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)

How do you guys think?

[kotarot]

@pvillard31 @ijokarumawak Thank you for your reviews.

At first, the purpose of my PR was, to enable to pick up a Log Level from the pull-down list (as we can do it on the LogAttribute processor), so that I would like to make it easier for users (including NiFi beginners) to use this processor.

As @ijokarumawak has suggested, should I fix it to be EL acceptable for flexible logging usages?

[pvillard31]

Yeah sounds good to me to have EL support ;)

[kotarot]

@pvillard31 @ijokarumawak Updated the property to support EL. Would you please check it?

[ijokarumawak]

LGTM, +1. Merging. Thanks @kotarot !