NIFI-5489: Add expression language support to AMQP processors HOST, V…

[danieljimenez]

…HOST and USER Fields.

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[danieljimenez]

No idea what the travis failures are, they are definitely not related to this change.

[danieljimenez]

After rerunning the Travis failures are gone.

[zenfenan]

LGTM. Will do a quick build and if everything works fine, I'll merge it.

[danieljimenez]

Awesome, thanks! That would mean it's targeted for 1.8.0, correct?

[danieljimenez]

Missed a spot evaluating the attribute expressions. Fixed.

[alopresto]

@danieljimenez correct, PRs merged now will be included in the next release. Because our bug fix releases (x.x.1) do not include feature work, this will be in the next minor release, which is 1.8.0.

[mosermw]

If you are using VARIABLE_REGISTRY to dynamically evaluate the Host, shouldn't you also allow it for Port?

[danieljimenez]

@mosermw I can, I just enabled the fields most likely to be variables for most use cases. If you'd like me to add that to this PR, I certainly can.

[mosermw]

Please do add Port to your PR, if you can, then I think this will also cover NIFI-4723. It looks like PORT_VALIDATOR already supports expression language, so you are good there.

[danieljimenez]

@mosermw Port added sir. :)

[mosermw]

+1 from me, though I didn't test this against a real RabbitMQ server. @zenfenan did you want to take another look?

[danieljimenez]

FWIW I am currently using a SNAPSHOT from 01782bf on a real RabbitMQ server.

[zenfenan]

Thanks @danieljimenez for the changes. Thanks @mosermw and @alopresto for the review. Built it with contrib-check profile enabled and ran a sample flow. Everything checks out as expected. Merged to the master.

[lukepfarrar]

Is there a reason why USER supports el but PASSWORD does not?

[alopresto]

Hi @lukepfarrar , we have a policy of not evaluating EL in password fields. Here is an example of that review process and the reasoning behind it on another PR.

Our policy so far has been that passwords do not support expression language, for a couple reasons:

1. How to evaluate if a password abc${def} should be interpreted as abc + the value of(def) or the literal string abc${def}
2. The variable registry is not designed to store sensitive values securely, so if a password is stored here, it can be accessed by an unauthorized user

[lukepfarrar]

I wondered if that was the case but it did not seem consistent with the DB pooling, which does/did allow EL in the password, although I notice that the scope has been tightened in recent versions.
Thanks :)

[alopresto]

There are definitely inconsistencies throughout the project as this wasn't always a firm policy and there are many different contributors to the project. As you noted, we have tried to tighten the reviews and catch this where we can, and hopefully with the completion of NIFI-5627, we will have a foundation to move forward on enabling EL in passwords for users.