A pluggable migration runner.

  • migrat

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0.2.13 years ago9 years agoMinified + gzip package size for migrat in KB


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Migrat is a pluggable Node.js migration tool designed for diverse stacks and processes. It is not tied any particular database engine and supports multi-node environments by differentiating migrations that should run on one node (to update a global database, for instance) and migrations that should run on all nodes (like updating a per-node cache).
$ npm install -g migrat


  • Migrations can be set to set to run once globally, or once per server.
  • Supports global locking during migration runs, to prevent multiple servers attempting to perform global migrations at the same time.
  • Pass context through to each migration. This can be a logging interface, a set of database connections, ... it's up to you.
  • Custom hooks throughout the migration process.
  • Perform dry runs to see the migration plan before it's executed.
  • Plugin-friendly (see below)


Migrat works great on its own, but it's even better with plugins to reduce boilerplate. Plugin list (the ones without links haven't been developed yet – help welcome (see the "Writing Plugins" guide):
- migrat-postgres – Locks, state storage, and migration files in pure SQL. - migrat-sh – Execute shell script migration files. - migrat-mysql – Locks, state storage, and migration files in pure SQL. - migrat-hipchat – Send live migration status to a HipChat room. - migrat-slack – Send live migration status to a Slack channel. - migrat-datadog – Send migration results to a Datadog dashboard. - migrat-php – Execute PHP migration files.
With plugins, you can have a migration directory that looks like:


migrat init migrat create migrat up

Usage Examples

$ migrat create add-user-table
# creates migrations/1413963352671-add-user-table.js

$ migrat create add-user-table --all-nodes
# creates migrations/1413963352671-add-user-table.all.js

$ migrat init  # set up a migrat project in the current directory
$ migrat up --dry-run  # show which migrations need to be run
$ migrat up [filename]  # get up to date (only forward)
$ migrat down <filename>  # go back to a specific migration


Migration Files

Migration files are pretty standard:
// (required) apply the change
module.exports.up = function(context, callback) { /* ... */ };

// (required) revert the change
module.exports.down = function(context, callback) { /* ... */ };

// (optional) verify the change took place
module.exports.check = function(context, callback) { /* ... */ };

You can also use async methods:
// (required) apply the change
module.exports.up = async function(context) { /* ... */ };

// (required) revert the change
module.exports.down = async function(context) { /* ... */ };

// (optional) verify the change took place
module.exports.check = async function(context) { /* ... */ };

Project Configuration

Migrat will look for for a migrat.config.js in your project directory, unless overriden by --config:
module.exports = {
    // REQUIRED. The folder to store migration scripts in.
    migrationsDir: './migrations',

    // REQUIRED. Where the current migration state specific to the
    // current machine is to be stored. This is only used to for
    // migrations created with the `--all-nodes` flag. Make sure
    // it is writable by the user executing migrat and isn't wiped
    // out between deploys.
    localState: '/var/lib/my_app/.migratdb',

    // OPTIONAL. Invoked at the beginning of a run, this method
    // should return an object with any details you want passed
    // through to all migrations. This can be database connections,
    // logging interfaces, etc.
    context: function(callback) {
        callback(null, {});

    // REQUIRED. Persists the current migration state. The `state`
    // argument will always be a variable-length string. Store it
    // to redis, disk, database, ... whatever suits you.
    storeState: function(state, callback) {

    // REQUIRED. This method is responsible for fetching the
    // current migration state, persisted by `storeState`.
    fetchState: function(callback) {
        callback(null, state);

    // OPTIONAL. Provide a function that returns a string to use
    // as the source for a new migration file. The `details`
    // argument will be an object containing:
    //   * "user"      The current user.
    //   * "filename"  The name of migration file.
    //   * "timestamp" The Date object used to put the timestamp
    //                 at the beginning of the migration filename.
    migrationTemplate: function(details, callback) {
        fs.readFile('path/to/template.js', 'utf8', callback);

    // OPTIONAL. Invoked at the beginning of a migration
    // run. Use this to establish a global lock. You can
    // either wait for a lock to become available, or fail.
    lock: function(callback) {

    // OPTIONAL (unless `lock` is implemented). Implement this to
    // release any global lock acquired by the `lock` function.
    unlock: function(callback) {

    // OPTIONAL. The number of milliseconds to give up after if
    // a lock cannot be obtained or released. This is only
    // applicable if the `lock` function is implemented.
    lockTimeout: 0,

    // OPTIONAL. Invoked at the very beginning of a run before
    // any locks are acquired or state is read. Use this to
    // establish any connections needed by `fetchState`,
    // `storeState`, `lock`, `unlock`, and `context`.
    initialize: function(callback) {

    // OPTIONAL. Callback executed right before all
    // queued migrations are executed.
    beforeRun: function(runlist, callback) {

    // OPTIONAL. Callback executed before each migration.
    beforeEach: function(runlist_item, callback) {

    // OPTIONAL. Callback executed after each migration.
    afterEach: function(err, runlist_item, callback) {

    // OPTIONAL. Callback executed right after all
    // queued migrations are executed.
    afterRun: function(err, runlist, callback) {

    // OPTIONAL. Invoked at the very tail end of a run once locks
    // are released and state has been stored. Use this to tear
    // down any connections established in `initialize`.
    terminate: function(callback) {


Before submitting pull requests, please update the tests and make sure they all pass.
$ npm test


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