sequelize migrations in heroku

When you initialize sequelize locally by running:

sequelize -i

a migration folder, config folder, and config.json inside the config folder are created. That json file is where you set the environments of your application. Here is an example of a config.json file.

{  "development": {  "username": "postgres",  "password": "password",  "database": "dbname",  "host": "100.0.0.0",  "dialect":"postgres",  "protocol":"postgres",  "port":"xxxx" },  "staging": {  "username": "dbusername",  "password": "dbpassword",  "database": "db",  "host": "host",  "dialect":"postgres",  "protocol":"postgres",  "port":"xxxx"  },  "production": {  "username": "dbusername",  "password": "dbpassword",  "database": "db",  "host": "dbhost",  "dialect":"postgres",  "protocol":"postgres",  "port":"xxxx"  }}

The production object is where you set your heroku production app database variables. You can access them by running the following in the command line:

heroku config --app production-app-name

All the variables will be in the database_url config var you set.

When you're ready to run a migration, all you run in the command line then is:

heroku run sequelize db:migrate --env production -m --app production-app-name. 

--env will be whichever database object in config.json you want migrated.

Instead of embedding passwords in a file, use this handy sequelize capability:

"production": {  "use_env_variable": "DATABASE_URL"}

Since March 2019, Heroku runs build npm script after each deploy. Improving the amazing comment above, you can add sequelize migration to it (locate in the package.json file, on root):

..."scripts": {  ...  "build": "sequelize db:migrate --env production && <other stuff to do before run the app>"}...