How to Deploy a Ruby on Rails App on PandaStack (Step-by-Step)

# How to Deploy a Ruby on Rails App on PandaStack (Step-by-Step)

Rails is one of those frameworks that should be easy to deploy but historically hasn't been. Heroku used to handle all of it — now you have to figure it out yourself. This guide shows you how to do it on PandaStack with a minimal Dockerfile and a managed PostgreSQL database.

What You'll Need

• A Rails app (Rails 7+)
• Docker installed locally
• A PandaStack account (free tier works)
• A GitHub repository

Step 1: Add a Dockerfile

Create a Dockerfile in your Rails root:

FROM ruby:3.3-slim

RUN apt-get update -qq && apt-get install -y \
  build-essential \
  libpq-dev \
  nodejs \
  && rm -rf /var/lib/apt/lists/*

WORKDIR /rails

COPY Gemfile Gemfile.lock ./
RUN bundle install --without development test

COPY . .

RUN SECRET_KEY_BASE_DUMMY=1 bundle exec rails assets:precompile

EXPOSE 3000

CMD ["bundle", "exec", "rails", "server", "-b", "0.0.0.0"]

Add a .dockerignore:

.git
log/
tmp/
test/
spec/
node_modules/
.env

Step 2: Configure for Production Environment

Make sure your config/database.yml reads from the DATABASE_URL environment variable:

production:
  url: <%= ENV['DATABASE_URL'] %>
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

Set RAILS_ENV=production and RAILS_SERVE_STATIC_FILES=true in your PandaStack environment variables — the latter because you're not running a separate Nginx in front of the container.

Step 3: Create a Managed PostgreSQL Database

In the PandaStack dashboard, go to Databases → New Database → PostgreSQL. Once provisioned, you'll get a DATABASE_URL that looks like:

postgresql://user:password@host:5432/dbname

Copy this for the next step.

Step 4: Deploy via Dashboard

1. 1Go to Projects → New Project → Container App
2. 2Connect your GitHub repository
3. 3PandaStack builds the Docker image automatically on each push
4. 4Add environment variables:

- DATABASE_URL — your managed PostgreSQL connection URL

- RAILS_ENV=production

- SECRET_KEY_BASE — generate with bundle exec rails secret

- RAILS_SERVE_STATIC_FILES=true

Step 5: Run Database Migrations

After the first deploy, open the PandaStack terminal or run:

panda exec --app my-rails-app -- bundle exec rails db:migrate

For subsequent deploys, you can add a migration step to your deployment config or handle it as part of your container startup.

Step 6: Handle Background Jobs (Sidekiq)

If you use Sidekiq, deploy it as a second container pointing at the same codebase with a different command:

CMD ["bundle", "exec", "sidekiq"]

Or use PandaStack's cronjob feature for lightweight scheduled tasks:

panda cronjob create \
  --name "rails-housekeeping" \
  --image your-org/rails-app:latest \
  --schedule "0 2 * * *" \
  --command "bundle exec rails cleanup:run"

Common Issues

Asset precompilation fails: Make sure RAILS_ENV=production is set at build time and your asset pipeline is configured correctly. The SECRET_KEY_BASE_DUMMY=1 trick lets assets compile without a real secret key.

Database connection errors: Double-check the DATABASE_URL is set correctly in PandaStack environment variables. Don't put it in the Dockerfile.

Slow boot times: Add config.eager_load = true in production.rb for faster request handling after startup.

Resources

• PandaStack docs: [docs.pandastack.io](https://docs.pandastack.io)
• Dashboard: [dashboard.pandastack.io](https://dashboard.pandastack.io)
• CLI install: npm install -g @pandastack/cli