@qelos/content/migrator/index.js

Content API for qelos platform

const { mongoUri } = require('../config')
const { MIGRATION_KEY } = require('./consts')

const mongoose = require('mongoose')
const connection = require('../server/models').connect(mongoUri)

const Configuration = mongoose.model('Configuration')

const currentInstance = Date.now() + Math.random()

connection
  .then(start)
  .then(() => process.exit(0))
  .catch((err) => {
    console.log('migration error!')
    console.error(err)
    process.exit(1)
  })

async function start () {
  console.log("migrator started");
  const {
    getCurrentMigrationHandler,
    clearCurrentMigrationHandler,
  } = require("./migration-handler");
  const {
    initMigrationConfig,
    getVersionConfig,
  } = require("./migration-config");
  const { runMigrationsForward } = require("./runner");

  const { migrationVersion } = require("../package.json");

  console.log("migration version: ", migrationVersion);

  let config = await getVersionConfig();
  // new app - create initial configs
  if (!config) {
    console.log("config is missing. creating first migration config.");
    await initMigrationConfig(1);
    config = await getVersionConfig();
  }
  // same version, nothing to do here.
  if (migrationVersion === config.metadata.latestContentMigration) {
    console.log(
      "project migration version is the same as latest migration. exit migrator."
    );
    return;
  }

  const { metadata } = await getCurrentMigrationHandler();
  // another pod / instance / replica is handling the migration
  if (metadata.isMigrationRunning) {
    console.log("another migrator is running. exist migrator.");
    return;
  }

  // update metadata to possess the migration process
  await Configuration.updateOne(
    { key: MIGRATION_KEY, "metadata.isMigrationRunning": false },
    {
      $set: {
        metadata: {
          isMigrationRunning: true,
          handler: currentInstance,
        },
      },
    }
  );

  // check if this current instance is possessing the migration process, if not - close process.
  const {
    metadata: { isMigrationRunning, handler },
  } = await getCurrentMigrationHandler();
  if (!(isMigrationRunning && handler === currentInstance)) {
    console.log("another migrator is handling the migration. exists.");
    return;
  }

  if (migrationVersion > config.metadata.latestContentMigration) {
    return runMigrationsForward(config.metadata.latestContentMigration).then(
      clearCurrentMigrationHandler,
      clearCurrentMigrationHandler
    );
  }
}