Drupal content snapshots for git branches

branch_snaps_post-checkout.php

#!/usr/bin/env php
<?php
/**
 * Git post-checkout hook that maintains Drupal db snapshots for each branch.
 *
 * INSTALLATION:
 * cd repo/root/directory
 * mkdir snapshots
 * echo "snapshots/*.sql" >> .git/info/exclude
 * chmod +x /path/to/branch_snaps_post-checkout.php
 * cd .git/hooks && ln -s /path/to/branch_snaps_post-checkout.php ./post-checkout
 */

$prev_head = $argv[1];
$new_head = $argv[2];
$checkout_type = $argv[3];
$snaps_enabled = (bool) trim(`git config branchsnaps.enable`);

if (!$snaps_enabled) {
  echo "Branch snapshots are disabled. Run `git config branchsnaps.enable 1` to enable.";
  return;
}

// We only care if we're checking out a branch from a different one.
if ($checkout_type == 1 && $prev_head !== $new_head) {
  $snapshot_dir = getcwd() . '/snapshots/';
  $prev_branch = trim(`git name-rev --name-only $prev_head`);
  $new_branch = trim(`git name-rev --name-only $new_head`);

  echo "Taking snapshot of $prev_branch and restoring snapshot of $new_branch...\n";

  // Create a snapshot of the db for the prev branch.
  `drush sql:dump --skip-tables-key=common --structure-tables-key=common --result-file={$snapshot_dir}{$prev_branch}.sql`;

  // Restore the snapshot of the new branch, if it exists.
  if (file_exists("{$snapshot_dir}{$new_branch}.sql")) {
    `drush sql:query --file={$snapshot_dir}{$new_branch}.sql`;
  }

  echo "Run `git config branchsnaps.enable 0` to disable branch snapshots.\n";
}

exit(0);

hi
Thanks for this code
I am new to git and haven't see the branchsnaps.enable before and can not find it on google