buildkite_bootstrap.sh

#!/usr/bin/env bash
# buildkite groups the builds by BUILDKITE_BRANCH.
# This allows us to arbitrarily group buildkite jobs, while still allowing
# agents to checkout, if change and revision id is passed in metadata.
set -euo pipefail
if buildkite-agent meta-data exists change_id && buildkite-agent meta-data exists revision_id; then
  change_id="$(buildkite-agent meta-data get change_id)"
  revision_id="$(buildkite-agent meta-data get revision_id)"
  partial_change_id="${change_id: -2:2}"
  # refs/changes/%s/%s/%s", changeID[len(changeID)-2:], changeID, revisionID)
  export BUILDKITE_BRANCH="refs/changes/${partial_change_id}/${change_id}/${revision_id}"

  echo "switched BUILDKITE_BRANCH to ${BUILDKITE_BRANCH}"
else
  echo "using BUILDKITE_BRANCH ${BUILDKITE_BRANCH}"
fi
exec buildkite-agent bootstrap "$@"