fix: update apt package lists before installing cbt CLI

[mutianf]

Description

Update cbt installation in .kokoro/build.sh to update apt package lists before installing, and support installing via gcloud components or modern google-cloud-cli-cbt package.

Root Cause

Previously, apt install -y google-cloud-sdk-cbt was called directly without running apt-get update. In older base images (such as gcr.io/cloud-devrel-kokoro-resources/java11), the cached package index referenced older package versions (e.g. google-cloud-cli-cbt 514.0.0-0) that had since been replaced and removed from packages.cloud.google.com/apt, causing 404 Not Found errors:

Err:1 http://packages.cloud.google.com/apt cloud-sdk/main amd64 google-cloud-cli-cbt amd64 514.0.0-0 404 Not Found
E: Failed to fetch http://packages.cloud.google.com/apt/pool/cloud-sdk/google-cloud-cli-cbt_514.0.0-0_amd64_03a51de04d51cdd23f7f8cb7ca02644d.deb 404 Not Found

Because set +e was active, the build continued without cbt installed, which caused subsequent tests requiring cbt (such as fuzz) to fail with cbt: command not found when attempting to create/delete test tables.

Solution

1. Check if cbt is already in PATH or in the same directory as gcloud.
2. If not found, attempt gcloud components install cbt --quiet.
3. If that fails, run apt-get update -y || true followed by apt-get install -y google-cloud-cli-cbt || apt-get install -y google-cloud-sdk-cbt (supporting sudo if present).
4. Verify and log cbt availability.

[gemini-code-assist]

Code Review

This pull request updates .kokoro/build.sh to robustly locate or install the cbt CLI tool, falling back to gcloud components or apt-get with or without sudo if necessary. The reviewer suggested refactoring the script to eliminate code duplication by extracting the PATH resolution logic into a helper function and using a bash array to conditionally prepend sudo for apt-get commands.

[gemini-code-assist]

There is significant code duplication in this block:

1. The logic to find cbt next to gcloud and add it to PATH is duplicated exactly twice (lines 50-56 and lines 75-81).
2. The apt-get update and install commands are duplicated with and without sudo (lines 65-71).

We can refactor this by:

• Extracting the PATH resolution logic into a helper function add_cbt_to_path.
• Using a bash array sudo_cmd to conditionally prepend sudo if available, avoiding the duplicated if/else block for apt-get.
• Removing the redundant -y flag from apt-get update (since update does not prompt for confirmation).

# Ensure cbt is in PATH if it's installed alongside gcloud but not in PATH
add_cbt_to_path() {
  if ! command -v cbt &> /dev/null && command -v gcloud &> /dev/null; then
    local gcloud_path
    gcloud_path=$(readlink -f "$(command -v gcloud)")
    local gcloud_bin_dir
    gcloud_bin_dir=$(dirname "${gcloud_path}")
    if [[ -x "${gcloud_bin_dir}/cbt" ]]; then
      export PATH="${PATH}:${gcloud_bin_dir}"
    fi
  fi
}

add_cbt_to_path

# Install cbt if it is not present
if ! command -v cbt &> /dev/null; then
  echo "Installing the cbt CLI command."
  if command -v gcloud &> /dev/null && gcloud components install cbt --quiet 2>/dev/null; then
    echo "cbt installed via gcloud components."
  else
    echo "Installing cbt via apt..."
    sudo_cmd=()
    if command -v sudo &> /dev/null; then
      sudo_cmd=(sudo)
    fi
    "${sudo_cmd[@]}" apt-get update || true
    "${sudo_cmd[@]}" apt-get install -y google-cloud-cli-cbt || "${sudo_cmd[@]}" apt-get install -y google-cloud-sdk-cbt
  fi

  # Ensure the newly installed cbt is in PATH
  add_cbt_to_path
fi