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Migrating Node.js app from Heroku to Fly.io

April 1, 2023

I recently migrated the Node.js app from Heroku to Fly.io, mainly due to reduced costs.

This blog post will cover the necessary steps in the migration process.

Prerequisites

  • Heroku app running

  • Use the exact versions for dependencies and dev dependencies in package.json so installation and build steps can pass successfully

  • Use the same Node.js version in Dockerfile, package.json, and GitHub Actions workflow

  • Use API gateway or custom domain for the service so web apps and mobile apps don't get affected by changing the URL of the service

Migration steps

  • Migrate environment variables and secrets

  • Migrate the Postgres database with the following commands (the ssl field in database configuration options is not needed)

fly secrets set HEROKU_DATABASE_URL=$(heroku config:get DATABASE_URL)
fly ssh console
apt update && apt install postgresql-client
pg_dump -Fc --no-acl --no-owner -d $HEROKU_DATABASE_URL | pg_restore --verbose --clean --no-acl --no-owner -d $DATABASE_URL
exit
fly secrets unset HEROKU_DATABASE_URL

  • Migrate the Redis database if it's used

  • Include the deployment step in the GitHub Actions workflow