DRILL-8276: Add Support for User Translation for Splunk Plugin

Description

Adds support for user translation in the Splunk plugin.

Documentation

Docs will be updated upon completion.

Testing

Added unit tests, tested manually.

This pull request introduces 1 alert when merging 778538064eb16f8d449b2f32b876b67ec2e19f5b into 6263f713891ddfbef547abf6dbd65bf12d1edf5d - view on LGTM.com

new alerts:

• 1 for Unused format argument

@jnturton This PR is now ready for review. As a note, I couldn't get this to work on my Mac M1 due to the lack of a ARM Docker Container for Splunk. Not sure how the Travis CI checks are passing.

This pull request introduces 1 alert when merging 64b9c3cd42528cae534f071aa29861af5781f74b into 51aaaafbdbe7d586f6e8a8137680ee7ccd738ced - view on LGTM.com

new alerts:

• 1 for Unused format argument

It looks like no attempt was made to run the Splunk tests on ARM. Perhaps this is because we separated out the running of the SlowTest category? @luocooong, do we run any SlowTests on ARM?

[INFO] --- maven-surefire-plugin:3.0.0-M7:test (default-test) @ drill-storage-splunk ---
[INFO] Tests are skipped.

It looks like no attempt was made to run the Splunk tests on ARM. Perhaps this is because we separated out the running of the SlowTest category? @luocooong, do we run any SlowTests on ARM?

[INFO] --- maven-surefire-plugin:3.0.0-M7:test (default-test) @ drill-storage-splunk ---
[INFO] Tests are skipped.

Just to be clear about it, there apparently is no working Docker container for Splunk on ARM. I did a lot of searching for this and all I found was a bunch of angry developer threads on Splunk's help boards1 2. (There are more but you get the idea)

I was able to start Splunk enough to run queries on my M1, but I couldn't get a containerized version to work at all.

I'm not too concerned because we know Drill runs on ARM, and the use case here would be for a user to connect to a remote Splunk installation.

I'm not too concerned because we know Drill runs on ARM, and the use case here would be for a user to connect to a remote Splunk installation.

I see it the same way, I just want to shed light on what's happening in Travis. I don't believe it's a concern for this PR.

@jnturton Thanks for the review. I revised the unit tests and added an additional test to verify that a query will fail with invalid credentials. I also fixed the LGTM alert.