Deploy NestJS Postgres Application To Heroku 😻

I have covered a lot of topics for Nestjs In this Post we are gong to talk about Nest js deployment

Deployment can be of different type like nestjs with mysql/postgres/mongo DB

• Common things is we need database resource on Heroku

There are many ways to push to Heroku, either we have CI/CD setup to push to Heroku of we just push the code to Heroku github Repo

developer -> push to master -> gitlab.ci/travis-ci/github actions -> deploy to Heroku -> restart application 

This is how any application gets deployed we merge to branch or we did commit and push it, it will trigger pipeline or we just push to heroku it will trigger Heroku build based on application type and then deploy application based on instruction in package.json

Example like HTTP REST APIs we need HTTP PORT and Database connection url to connect to

The basic approach to hosting a Node application on Heroku is:

• Have your package.json file define any required dependencies (e.g. the dependencies that will already be there)
• Specify what node version you want to use in package.json
• Specify a start script in package.json that tells Heroku how to start your application after installing everything
• Push your code up to Heroku using git push heroku master

Things are not simple when we have typescript project as we have to build project first and then run code from /dist folder for nestjs application

step-1 [PORT Dynamic]

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.enableCors();
  await app.listen(process.env.PORT || 3000);
}

Always add PORT dynamic as heroku will assign its own port for HTTP server

update package.json file

Modify the start:prod command in package.json:

"start:prod": "node dist/src/main.js",
"prestart:prod": "npm run build",

Before we can run the start:prod command we will need to run the prestart:prod command which actually performs the build and creates our dist folder with the built files. To do this, we can add a postinstall script which will automatically run after Heroku has finished installed the dependencies for the project.

"postinstall": "npm run prestart:prod",

Now it will do npm install => script prestart:prod => start Prod script

Finally Proc File

If you want to add custom comand which you want to run to bootstrap application that you can add in proc file

Finally, we just need to create a Procfile. This allows us to specifically supply the command we want to run to start the application rather than the default start script (which we want to keep for our local development environment).

Create a file called Procfile at the root of your project and add the following:

web: npm run start:prod

create application and push code

Now lets build heroku application and push code

git add .
git commit -m "doing it live"
git push heroku master

How to run Migrations

with deployment also we can do database migration against dev and Prod database Lets say i am using typeORM ORM for dealing with migration then i can add command to run migration with application bootstrap Like

web: npm run migration:run && npm run start:prod

Here npm run migration:run should look into migration folder and run changes in database tables to add/update database Please check TypeORM to know more about Migration Using this simple command we can update database by executing migrations Heroku Provided Integration with all different database like postgres, mysql. we can add database for deployment environment from heroku console, example https://www.heroku.com/postgres