Release build script builds JVM components from wrong branch

[andygrove]

Describe the bug

Description

The build-release-comet.sh script has a bug where it builds native binaries from the specified branch (via -b flag) but builds JVM components from whatever branch is currently checked out on the host machine. This can result in mismatched releases where native code and JVM code come from different branches.

Steps to Reproduce

1. Check out main branch on host machine
2. Run the release build script with a different branch specified:

   ./build-release-comet.sh -b branch-0.13

3. Observe the resulting artifacts

Expected Behavior

The entire build (both native binaries and JVM components) should be built from the branch specified via the -b flag (branch-0.13 in this example).

Actual Behavior

• Native binaries are correctly built from branch-0.13 (inside Docker containers)
• JVM components and git hash are built/captured from main (on the host machine)

This creates a mismatched artifact that combines code from two different branches.

Root Cause

The script has two separate build phases:

1. Native binaries (lines 132-160): Built inside Docker containers that properly clone the repo and checkout the specified branch

   docker run ... $BUILDER_IMAGE_AMD64 "${REPO}" "${BRANCH}" amd64

2. JVM components (lines 196-209): Built on the host machine from whatever is currently checked out

   pushd $COMET_HOME_DIR
   GIT_HASH=$(git rev-parse --short HEAD)  # Gets hash from current checkout!
   ./mvnw install  # Builds from current checkout!

The script never switches branches on the host machine before building the JVM components.

Proposed Solutions

Option 1: Check out the branch on host (Recommended)

Add a git checkout before building JVM components:

pushd $COMET_HOME_DIR
git checkout "${BRANCH}"  # Add this line
GIT_HASH=$(git rev-parse --short HEAD)
./mvnw install
popd

Option 2: Document the requirement

If the script is intended to build JVM components from the current branch, document this clearly:

• Update the usage message to indicate the user must be on the correct branch
• Add a validation check that fails if the current branch doesn't match the -b parameter

Option 3: Build everything in Docker

Build JVM components inside the Docker container alongside the native binaries to ensure consistency.

Impact

This bug can lead to:

• Release artifacts that combine code from multiple branches
• Version mismatches between native and JVM components
• Difficult-to-debug issues when the release doesn't behave as expected
• Incorrect git hashes in release metadata

Environment

• Script: dev/release/build-release-comet.sh
• Affected versions: Current main branch

Steps to reproduce

No response

Expected behavior

No response

Additional context

No response