--- title: Debug Rails Deployments url: "/docs/debug/rails/" canonical_url: https://docs.blossom88.com/docs/debug/rails/ markdown_url: https://docs.blossom88.com/docs/debug/rails.md summary: Common issues and solutions for deploying Ruby on Rails applications on Blossom categories: - debugging - frameworks - ruby - rails - troubleshooting --- # Debug Rails Deployments This guide covers common issues and solutions encountered when deploying Ruby on Rails applications, especially during the first deployment. ## Minimum Env Variables Example of the env variables that Rails apps usually use: RAILS_ENV=production RAILS_SERVE_STATIC_FILES=true RAILS_MASTER_KEY=value SECRET_KEY_BASE=value DATABASE_URL=postgresql://user:pass@host:5432/demo # If using the db for cable, cache and queue # gems: solid_cable solid_cache solid_queue CABLE_DATABASE_URL=postgresql://user:pass@host:5432/demo_cable CACHE_DATABASE_URL=postgresql://user:pass@host:5432/demo_cache QUEUE_DATABASE_URL=postgresql://user:pass@host:5432/demo_queue Notes: - **RAILS_SERVE_STATIC_FILES**: Allows the Rails app server to serve compiled assets from `public/assets`. This is useful for simple deployments and examples where a CDN or dedicated static asset host is not configured. - **RAILS_MASTER_KEY**: Decrypts credentials file, eg: config/credentials/production.yml.enc Allows Rails to read secrets. To get the value `cat config/credentials/production.key` - **SECRET_KEY_BASE**: Signs/encrypts cookies & sessions. Keeps cookies, sessions, CSRF tokens secure. Can use `rails secret` to generate a new value. More debugging tips below: ## Common First Deployment Checklist & Issues Here are frequent problems and configuration points to check: ### 1. Credentials & Master Key - **Error:** `ActiveSupport::MessageEncryptor::InvalidMessage` - **Cause:** This usually means the `RAILS_MASTER_KEY` environment variable is missing or incorrect in your production environment. Rails cannot decrypt `config/credentials/production.yml.enc` without the correct key. - **Solution:** - Ensure the `RAILS_MASTER_KEY` environment variable is set correctly in your production server/hosting environment. You can find the value for the in `config/production.key` (do not commit this file!). - If you haven't initialized encrypted credentials for production, run: rails db:encryption:init - To edit production credentials: EDITOR="code --wait" bin/rails credentials:edit --environment=production - Commit the generated `config/credentials/production.yml.enc` file. ### 2. Secret Key Base - **Error:** Application might fail to start or session errors might occur. - **Cause:** Rails requires a `SECRET_KEY_BASE` environment variable for signing sessions and other security features. Some platforms (like Heroku buildpacks) might generate a temporary one during the build, which won't match the one expected by your running application if you've set one in your credentials. - **Solution:** Ensure the `SECRET_KEY_BASE` environment variable is explicitly set in your production environment. You can generate a suitable key using `bin/rails secret` and store it securely (often in your production credentials or directly as an environment variable). ### 3. Host Authorization - **Error:** `Blocked host: ...` or `ActionDispatch::HostAuthorization::DefaultResponseApp` errors in logs, potentially leading to HTTP 403 Forbidden pages. - **Cause:** Rails has a security feature preventing DNS rebinding attacks by only allowing requests from explicitly permitted hostnames. - **Solution:** Configure allowed hosts in `config/environments/production.rb`: ```ruby # config/environments/production.rb config.hosts = [ "your_domain.com", # Your primary domain "www.your_domain.com", # Optional: www subdomain # Add any other domains or subdomains that should access your app # You can also use regular expressions: # /\.example\.com$/ # Allows any subdomain of example.com ] # If testing without SSL initially, you might temporarily clear hosts, # but **do not leave this in production**: # config.hosts.clear ``` ### 4. SSL Configuration - **Initial Testing:** When first deploying, you might temporarily disable SSL enforcement to simplify debugging connectivity issues. **Remember to re-enable SSL for production.** - **Configuration (`config/environments/production.rb`):** ```ruby # Temporarily disable for initial tests (NOT recommended for live production): # config.force_ssl = false # Standard Production Settings: config.force_ssl = true # If behind a proxy that handles SSL termination: # config.assume_ssl = true ``` ### 5. Static Assets - **Error:** CSS or JavaScript files under `/assets/...` return HTTP 404, and the app loads without styling. - **Cause:** Rails production usually expects static assets to be served by a CDN, reverse proxy, or asset host. For simple Blossom examples, it is acceptable for Rails itself to serve compiled assets. - **Solution:** Enable the public file server with an environment variable: RAILS_SERVE_STATIC_FILES=true The production config should use the standard Rails toggle: ```ruby config.public_file_server.enabled = ENV["RAILS_SERVE_STATIC_FILES"].present? ``` ## Database Setup - **Requirement:** The production database needs to be created, migrated, and potentially seeded. - **Commands:** Run these on your production server or via your deployment process: RAILS_ENV=production rails db:create RAILS_ENV=production rails db:migrate RAILS_ENV=production rails db:seed # Optional You can add these to the Environment's release hook. ## Troubleshooting Tools When debugging deployment issues, check the following: - **Rails Application Logs:** If you app is logging to stdout, then they will show up Blossom App Logs UI for debugging. ## Useful Commands - **Build with Buildpacks (Example):** You can install the pack tool and try building it on your own machine for debugging. pack build test --path . --builder heroku/builder:24 - **Check Production Credentials:** rails credentials:show -e production