Add support for ranger 2.0

[PedroRossi]

As mentioned in https://github.com/yaooqinn/spark-ranger/issues/4, this PR proposes adding another version of the RangerAdminClientImpl with complies with the RangerAdminClient interface which has more methods since Ranger 2.0

Changes made:

• added the travis config to build Spark 2.3 and 2.4 using Ranger 2.0
• added maven specific config to specify which Ranger class to use during test-compile
• the RangerAdminClientImpl was refactored into a trait so we could extend the original RangerAdminClient interface and re-use the trait

[PedroRossi]

@yaooqinn I noticed you already add the travis config on https://github.com/yaooqinn/spark-ranger/pull/7, should I remove this config from my PR then?

[PedroRossi]

@yaooqinn I also noticed that the config ranger.plugin.spark.policy.source.impl in the file ranger-spark-security.xml is not being used on the tests (I tried using a random name and the tests were still ok) and I also noticed that you have a sample policy, how are the tests working with it? I didn't understand this part well

[codecov[bot]]

Codecov Report

Merging #9 into master will increase coverage by 0.8%. The diff coverage is n/a.

@@            Coverage Diff             @@
##             master      #9     +/-   ##
==========================================
+ Coverage        40%   40.8%   +0.8%     
- Complexity       96     104      +8     
==========================================
  Files            25      25             
  Lines           855     865     +10     
  Branches        283     286      +3     
==========================================
+ Hits            342     353     +11     
+ Misses          407     319     -88     
- Partials        106     193     +87

Impacted Files	Coverage Δ	Complexity Δ
...lyst/optimizer/RangerSparkRowFilterExtension.scala	60.37% <0%> (-1.03%)	16% <0%> (ø)
.../org/apache/spark/sql/hive/PrivilegesBuilder.scala	19.8% <0%> (+0.96%)	0% <0%> (ø)	:arrow_down:
...yst/optimizer/RangerSparkAuthorizerExtension.scala	32.96% <0%> (+9.59%)	17% <0%> (+8%)	:arrow_up:

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[yaooqinn]

@yaooqinn I also noticed that the config ranger.plugin.spark.policy.source.impl in the file ranger-spark-security.xml is not being used on the tests (I tried using a random name and the tests were still ok) and I also noticed that you have a sample policy, how are the tests working with it? I didn't understand this part well

Hmm... I don' t remember well. So can we just rm this conf and the class to see if it works well?

[PedroRossi]

We can rm the class but not the conf, I already tested it, but not for all of the Ranger versions.

Going to test this later then send a report here

[yaooqinn]

I see. If that config is configured wrong or missed, the org.apache.ranger.admin.client.RangerAdminRESTClient will be used.

I guess we just need class RangerAdminClientImpl extends RangerAdminRESTClient to fix the issue here.

[PedroRossi]

RangerAdminRESTClient

This fixed the issue and it is better because we don't need to change the pom in this case

[PedroRossi]

@yaooqinn I also noticed that the config ranger.plugin.spark.policy.source.impl in the file ranger-spark-security.xml is not being used on the tests (I tried using a random name and the tests were still ok) and I also noticed that you have a sample policy, how are the tests working with it? I didn't understand this part well

Hmm... I don' t remember well. So can we just rm this conf and the class to see if it works well?

It works fine without this conf, we can remove this class and this conf since we do not leverage a Ranger for retrieving the policy

[yaooqinn]

Let's keep them, this class helps to debug when we add more policies to test resources.

[yaooqinn]

LGTM, could you also update README?

[yaooqinn]

merged to master, thanks for your help:)