Heroku deployment in Ruby on Rails - Step-by-Step Execution

Concept Flow - Heroku deployment

Prepare Rails app

↓

Create Git repo

↓

Login to Heroku CLI

↓

Create Heroku app

↓

Add Heroku remote to Git

↓

Push code to Heroku

↓

Heroku builds and deploys

↓

App runs on Heroku server

This flow shows the steps to deploy a Rails app to Heroku, from preparing code to running live.

Execution Sample

Ruby on Rails

git init
heroku login
heroku create myapp
git push heroku main
heroku run rails db:migrate

This code initializes git, logs into Heroku, creates an app, pushes code, and runs database migrations.

Execution Table

Step	Action	Command/Process	Result/Output
1	Initialize Git repository	git init	Git repo created locally
2	Login to Heroku	heroku login	User authenticated with Heroku
3	Create Heroku app	heroku create myapp	Heroku app 'myapp' created with URL
4	Add Heroku remote	git remote add heroku https://git.heroku.com/myapp.git	Heroku remote linked to Git
5	Push code to Heroku	git push heroku main	Code pushed; Heroku builds and deploys app
6	Run database migrations	heroku run rails db:migrate	Database schema updated on Heroku
7	Open app in browser	heroku open	App runs live on Heroku server
Exit	Deployment complete	-	App is live and ready to use

💡 All steps completed successfully; app deployed and running on Heroku

Variable Tracker

Variable	Start	After Step 3	After Step 5	Final
Git repo	Not initialized	Initialized	Code pushed to Heroku	Code on Heroku remote
Heroku app	None	Created 'myapp'	App built and deployed	App running live
Database schema	Local only	Local only	Migrated on Heroku	Up to date on Heroku

Key Moments - 3 Insights

Why do we need to run 'heroku run rails db:migrate' after pushing code?

Because the database on Heroku is separate and needs schema updates; see execution_table step 6.

What happens if you forget to add the Heroku remote before pushing?

Git won't know where to push the code; step 4 shows linking remote is required before step 5.

Why do we use 'git push heroku main' instead of just 'git push'?

Because 'heroku' is a special remote for deployment; pushing to it triggers Heroku build and deploy (step 5).

Visual Quiz - 3 Questions

Look at the execution table, what command creates the Heroku app?

A git init

B git push heroku main

C heroku create myapp

D heroku run rails db:migrate

💡 Hint

Check step 3 in the execution_table where the app is created.

At which step is the code actually sent to Heroku servers?

A Step 4

B Step 5

C Step 2

D Step 6

💡 Hint

Look for 'git push heroku main' in the execution_table.

If you skip running 'heroku run rails db:migrate', what happens?

A Database schema on Heroku will be outdated

B Git remote will be missing

C App will not build

D Heroku app won't be created

💡 Hint

See step 6 in execution_table about database migrations.

Concept Snapshot

Heroku Deployment for Rails:
1. Initialize Git repo with 'git init'.
2. Login to Heroku CLI using 'heroku login'.
3. Create app with 'heroku create appname'.
4. Add Heroku remote to Git.
5. Push code using 'git push heroku main'.
6. Run 'heroku run rails db:migrate' to update database.
7. App runs live on Heroku URL.

Full Transcript

Deploying a Rails app to Heroku involves several clear steps. First, you prepare your Rails app and initialize a Git repository locally. Then, you log in to Heroku using the Heroku CLI. Next, you create a new Heroku app which gives you a unique URL and Git remote. You add this remote to your local Git configuration. After that, you push your code to Heroku using 'git push heroku main', which triggers Heroku to build and deploy your app. Since the database on Heroku is separate, you run migrations there with 'heroku run rails db:migrate'. Finally, your app is live and accessible on the web. Each step builds on the previous, ensuring your app is properly deployed and ready for users.

Practice

1. What is the main purpose of deploying a Rails app to Heroku?

easy

A. To put the app online without managing servers

B. To write Ruby code faster

C. To create a local database

D. To debug Rails code automatically

Solution

1. Step 1: Understand Heroku's role

   Heroku is a platform that hosts apps so they can be accessed online without you managing the servers.

2. Step 2: Compare options

   Options B, C, and D describe development or debugging tasks, not deployment.

3. Final Answer:

   To put the app online without managing servers -> Option A

4. Quick Check:

   Heroku deployment = online app hosting [OK]

Hint: Heroku hosts apps online, no server setup needed [OK]

Common Mistakes:

• Confusing deployment with coding or debugging
• Thinking Heroku manages local databases
• Assuming Heroku speeds up writing code

2. Which command is used to push your Rails app code to Heroku?

easy

A. heroku push

B. heroku deploy app

C. rails deploy

D. git push heroku main

Solution

1. Step 1: Identify the correct git command

   Heroku uses git to receive code. The correct command is 'git push heroku main' to push the main branch.

2. Step 2: Check other options

   Options A, C, and D are not valid commands for pushing code to Heroku.

3. Final Answer:

   git push heroku main -> Option D

4. Quick Check:

   Push code with git push heroku main [OK]

Hint: Use git push heroku main to deploy code [OK]

Common Mistakes:

• Using 'heroku push' which is invalid
• Trying 'rails deploy' which doesn't exist
• Confusing Heroku CLI commands

3. After pushing your Rails app to Heroku, which command runs database migrations on Heroku?

medium

A. heroku run rails db:migrate

B. rails db:migrate

C. git migrate heroku

D. heroku migrate db

Solution

1. Step 1: Understand migration on Heroku

   To run migrations on Heroku's remote server, you use 'heroku run rails db:migrate'.

2. Step 2: Check other commands

   'rails db:migrate' runs locally, 'git migrate heroku' and 'heroku migrate db' are invalid commands.

3. Final Answer:

   heroku run rails db:migrate -> Option A

4. Quick Check:

   Run migrations remotely with heroku run rails db:migrate [OK]

Hint: Run migrations remotely with heroku run rails db:migrate [OK]

Common Mistakes:

• Running migrations locally instead of on Heroku
• Using invalid git commands for migration
• Confusing command order

4. You pushed your Rails app to Heroku but see an error when opening the app URL. What is a common cause?

medium

A. You did not install Ruby locally

B. You used 'git push origin main' instead of 'git push heroku main'

C. You forgot to run database migrations on Heroku

D. You opened the wrong browser

Solution

1. Step 1: Identify common deployment errors

   Forgetting to run migrations on Heroku often causes errors because the database schema is not updated.

2. Step 2: Evaluate other options

   You used 'git push origin main' instead of 'git push heroku main' means code wasn't pushed to Heroku, but question says code was pushed. Options A and D are unrelated to deployment errors.

3. Final Answer:

   You forgot to run database migrations on Heroku -> Option C

4. Quick Check:

   Missing migrations cause app errors on Heroku [OK]

Hint: Run migrations after push to avoid errors [OK]

Common Mistakes:

• Ignoring migrations after deployment
• Confusing git push origin with heroku
• Blaming local environment for Heroku errors

5. You want to deploy a Rails app with environment variables for API keys on Heroku. Which is the correct way to set them before deployment?

hard

A. Add keys to config/application.rb file

B. Use 'heroku config:set KEY=value' command

C. Store keys in a local .env file only

D. Push keys directly in your code files

Solution

1. Step 1: Understand environment variables on Heroku

   Heroku uses 'heroku config:set' to securely store environment variables like API keys.

2. Step 2: Evaluate other options

   Adding keys to config/application.rb or pushing keys in code risks exposure. Local .env files are not sent to Heroku.

3. Final Answer:

   Use 'heroku config:set KEY=value' command -> Option B

4. Quick Check:

   Set env vars securely with heroku config:set [OK]

Hint: Use heroku config:set to add env variables securely [OK]

Common Mistakes:

• Hardcoding keys in code risking leaks
• Relying on local .env files for Heroku
• Editing config/application.rb for secrets