Streamline how VERSION is provided for all assembly and deployment rules

[haikalpribadi]

At the moment, we have different ways to VERSION our distribution for assembly and deployment.

For example, for assemble_rpm and deploy_rpm, we strictly rely on the content of the //:VERSION file, so we overwrite the file before calling assembling or deploying.

echo $(cat VERSION)_$CIRCLE_SHA1 > VERSION && cat VERSION
bazel run //:deploy-rpm -- snapshot

For assemble_maven and deploy_maven, we repackage the JAR at deployment with the version we want:

bazel run //common:deploy-maven -- snapshot $CIRCLE_SHA1
bazel run //common:deploy-maven -- release $(cat VERSION)

This is very inconsistent, and in cases where we need to overwrite the //:VERSION file, it's actually problematic/error-prone: what if we a developer forgets to update the //:VERSION file and calls bazel run //:deploy-rpm -- snapshot, because it's not one canonical step?

Let's streamline the way version our distribution for all assembly and deployment rules as described below.

1. Assembly rules do not take in version_file = "//:VERSION" any more, and can optionally be versioned using Bazel environment variables. For example:

   • bazel build //common:assemble-maven will produce a Maven JAR with version 0.0.0 (aka. "unversioned").
   • bazel build --define version=$GIT_SHA //common:assemble-maven will produce Maven JAR with a git commit as the version.
   • bazel build --define version=$(cat VERSION) //common:assemble-maven will produce a Maven JAR with the content of //:VERSION (e.g. 1.5.7) as the version.

2. Deployment rules remain to be parameterised with release or snapshot, but do not take in any version arguments any more. They will verify the distribution they receive from assembly rules is versioned properly, unique to each platform's versioning syntax requirements. For example:

   • bazel run //common:deploy-maven -- snapshot will make sure that the Maven jar is not versioned 0.0.0 (i.e. not "unversioned")
   • bazel run //common:deploy-maven -- snapshot will make sure that they Maven jar is semantically version (X.Y.Z-*) (this just an example)
   • bazel run //:deploy-rpm -- release will make sure that the RPM distro is versioned X.Y.Z-{architecture} (this is just an example)

The above design should be applied to all assemble_* and deploy_* rules.

[haikalpribadi]

Make sure to also apply the same design to assemble_zip and assemble_targz, so we can get rid of this annoying wait time @vmax :