elasticsearch-migrate

Package to help you run one time migrations into your Elasticsearch DB such as Creating an index, inserting master data etc.

Note: This package is still in active development, use it in production with caution.

What it does

Two indices will be created in your Elasticsearch instance.

Example: nodejs_migrations, nodejs_migrations_lock

One for storing the migration file names that already ran, other for updating a lock if the migrations are running currently, to avoid duplication of migrations in a muliple instances scenario.

How to use elasticsearch-migrate

Assuming the below project structure

├── src
│  │──db
│  │  ├── bootstrap-db.js
│  │  ├── es-client.js
│  │  ├── es-migrations
│  │  │  ├── 01-create-index.js
│  │  │  ├── 02-update-schema.js
│  │  │  ├── 03-update-again.js
│  │  │  └── 04-update-4.js
│  │──index.js

With below file contents

index.js

import { bootstrapDb } from './db/bootstrap-db';

bootstrapDb();

db/es-client.js Exports the Elasticsearch client instance

import { Client } from '@elastic/elasticsearch';

export const client = new Client({
  node: process.env.ELASTICSEARCH_HOST
});

db/bootstrap-db.js

import { migrateLatest } from 'elasticsearch-migrate';
import { client } from './es-client';

export async function bootstrapDb() {
  await migrateLatest({
    indexName: 'documents_migrations',
    client,
    directory: __dirname + '/es-migrations'
  });
}

Read more about the input given to migrateLatest below

interface MigrationConfig {
  /**
   * Name of the index in which the migrations
   * have to be stored/read.
   */
  indexName: string;
  /**
   * Path to the directory in which migration
   * files are present
   */
  directory: string;
  /**
   * Elasticsearch Node.js client instance
   */
  client: Client;
  /**
   * Timeout to wait until the migration
   * lock is released.
   * Default: 60000
   */
  migrationLockTimeout?: number;
}

db/es-migrations/01-create-index.js Example Migration file

export async function migrate(client) {
  await client.indices.create({
    index: 'new_index',
    body: {
      mappings: {
        properties: {}
      }
    }
  });
}

The exported function must be named migrate for the migrations to run.

Once the above function is executed succesfully (as-in the Promise is resolved without error), a record with the filename will be inserted in documents_migrations, and will be skipped execution in future as it is present in the index.

Errors

Error	Reason
MigrateFunctionImportFailedError	If importing migrate function from migration file fails. Only CommonJS modules supported as of now.
MigrationLockTimedOutError	If the `migrationLockTimeout` value is exceeded. Default: `60000` ms. If you don't have muliple instances and still the issue araises, try releasing the lock manually
MigrationFileMissingError	If a record with migration file name exists in migrations index, but not in the given migrations directory. Check if you have accidentally deleted a file in the directory
MigrationRunFailedError	If an error is thrown by a migrate function while running it. Use try/catch blocks to narrow down the issue.