Bazel builds enabled along with sbt

[krisnaru]

Summary

• Enabled bazel builds for sources, tests
• Sbt works as is
• Supported scala versions: 2.12 and 2.13
• Supported spark versions 3.1, 3.2,3.5

Why / Goal

Goal is to improve the build environment(by sandboxing) and provide multiple spark versions

Test Plan

Unit testing green
quick start steps green https://chronon.ai/getting_started/Tutorial.html

Build commands

• bazel build //service
• bazel build //online
• bazel build //api/...
• Uber jar: bazel build //spark:spark-assembly_deploy.jar
• Build for scala version and spark version
  bazel build --config scala_2.12 --define spark_version=3.2 //spark/...

Checklist

• Readme updates
• Publish maven artifacts

Reviewers

@nikhilsimha @piyush-zlai

[nikhil-zlai]

LGTM! This is massively impactful Krish! Thanks for putting this up.

[piyush-zlai]

Thanks for taking the time to make this PR. Swapping over to bazel would be great for chronon!
Couple of comments / qs:

• Lets also add some notes on how devs can use build / add deps etc using bazel in the devnotes
• While we're keeping sbt & bazel around in the transitionary period, is there anything we need to call out for folks to take care of while updating deps / such?

[mears-stripe]

Thanks!! Excited about the project being bazel-fied!

[hzding621]

LGTM! Left a comment about maintaining bazel/SBT consistency as other comments also mentioned.

🙏 Thanks for contributing - this is huge!

[pengyu-hou]

we are getting really close but the last commit seems breaking the build. Could you reproduce it with the sbt build?

[error] IO error while decoding /Users/pengyu_hou/workspace/chronon/spark/src/main/spark-default/ai/chronon/spark/EncoderUtil.scala with UTF-8: /Users/pengyu_hou/workspace/chronon/spark/src/main/spark-default/ai/chronon/spark/EncoderUtil.scala (No such file or directory)

[pengyu-hou]

Thanks for making the change and being patient with our review process. Looking forward to phase 2.