Bye Heroku, hey Fly.io

I still remember the first time I deployed a database backed website with a single command, it completely blows my mind and the tool made it possible was Heroku. Nowadays when talking about containerization, Docker/k8s gets mentioned a lot, but the real pioneer in that space (PAAS) is Heroku, at least to me. It offloads the burden of provisioning (e.g. bins/libs installation), scaling (e.g. load balancing), dealing with security (e.g. tls/ssl termination) and a lot other chores from programmers, so that they only need to focus on building the app. However, Heroku recently (11/28) cancelled its free plan for all customers. As a result, I did a bit research to look for an alternative and came across another great tool - fly.io.

Background

One practical reason I’m looking for a Heroku alternative is that I’m using its Heroku Postgres service. The comment system of this blog is powered by https://github.com/djyde/cusdis thanks to Randy (the creator), self hosted by Vercel (compute) and Heroku Postgres (storage) with a simple comment form widget (iframe) at the bottom of this page. Since it's mostly a quiet blog, the free-tier plan of both services is more than enough for comments.

Migration Guide

Migrate a Postgres Database from Heroku

Beta documentation. This documentation has been recently released, but may still need improvements and clarifications. Please provide feedback for this documentation in our community forums or edit on github. This guide runs you through how to migrate a database off of Heroku and onto Fly.io, but before that, let's go over some major differences between Heroku's managed Postgres offering and Fly.io's Postgres offering.

https://fly.io/docs/postgres/getting-started/migrate-from-heroku/

Smart move, isn't it?

Migration Steps

Breaking down into 2 parts, 1) Migrating the data to Fly Postgres 2) Exposing to external connections (i.e. DB_URL for above Vercel app to connect).

Migrating the data to Fly Postgres

Provision database app


fly pg create -n "cusdis-db"


fly secrets set -a cusdis-db DATABASE_URL=postgres://postgres:<password>@cusdis-db.internal:5432

Data transfer


fly secrets set -a cusdis-db HEROKU_DATABASE_URL=$(heroku config:get -a cusdis2 DATABASE_URL)


fly ssh console -a cusdis-db
createdb --maintenance-db $DATABASE_URL cusdis
pg_dump -Fc --no-acl --no-owner -d $HEROKU_DATABASE_URL | pg_restore --verbose --clean --no-acl --no-owner -d $DATABASE_URL/cusdis


fly secrets unset HEROKU_DATABASE_URL DATABASE_URL -a cusdis-db

Verify


fly pg connect -a cusdis-db -d cusdis

Exposing to external connections

(based on https://fly.io/docs/postgres/connecting/connecting-external/)

IP allocation


fly ips allocate-v4 -a cusdis-db

Expose external port

Pull down fly.toml configuration file


fly config save --app cusdis-db

Update above configuration file


[[services]]
  internal_port = 5432 # Postgres instance
  protocol = "tcp"
[[services.ports]]
  handlers = []
  port = 10000

Deploy and verify changes


fly deploy -a cusdis-db --image flyio/postgres:14
fly info -a cusdis-db

Wrap up

By combining IP and public port above, we should be able to get the database url, something that looks like postgres://postgres:<pasword>@<host IPv4 address>:10000/cusdis . Just replace the old url with this new one and test with a few comments, then we should be 🥂.

Caveats

New incoming data to Heroku during the migration will be missed (see https://fly.io/docs/postgres/getting-started/migrate-from-heroku/ for more details)

Rename. i.e. replace cusdis-db appeared in above commands with your own app-db name