May 13, 2016

Heroku troubleshooting

Everytime I get an error from Heroku, it is typically time-consuming to troubleshoot without any resources at hand. So I decide to write up my past Heroku troubleshooting experiences for my future self.

Before starting

Relax, do not panic
Read error messages thoroughly
What changes did you make since there was no error.

Diagnosing errors at Heroku

$ heroku logs
$ heroku run rails console
$ heroku run console --sandbox

Some possible causes

Some code got broken when refactoring.
ActiveRecord associations are not properly handled.
The database schema is not updated.
Ruby version changed
vendor/cache
Gem that heroku requires (pg)
Heroku configuration (buildpacks, etc)

Troubleshooting I did in the past

Error: Some gems seem to be missing from your vendor/cache directory

$ git rm -rf vendor/cache
$ git add ...
$ git commit ...
$ git push heroku master

Error: failed to push some refs to ‘https://git.heroku.com/my-app.git’

Read the error message throughly. Often there is a clue in messages.

Missing files

Check if you accidentally delete directories in such as config, public.
Check .gitignore for untracked files.

Missing gems

$ git rm Gemfile.lock
$ bundle install
$ git add ...
$ git commit ...
$ git push heroku master

Error: Heroku deployment error H10 (App crashed)

Didn’t you modify db or something?
Most likely something is broken in your code (association etc).

Check if the production database is up-to-date

$ git push heroku master     # Push up to Heroku repo
$ heroku pg:reset DATABASE   # reset the production database

Missing CSS on Heroku Deployment

Rails Asset Pipeline on Heroku Cedar
$ RAILS_ENV=production bundle exec rake assets:precompile

Check if the current Heroku app name is registered

$ git remote -v
$ git remote rm heroku
$ git remote add heroku git@heroku.com:APP_NAME.git

js files not loading in production but working well locally

Require all the necessary script files in app/assets/javascripts/application.js
Precompile the assets for production

# Precompile the assets for production
$ RAILS_ENV=production bundle exec rake assets:precompile
# Note: If Devise.secret_key is not set, add one to your Devise initializer

Check Heroku-supported Ruby/Rails versions

An error occurred while installing Ruby ruby-x.y.z

Check if Sendgrid is configured (if applicable)

Configuring Rails to use SendGrid in production

$ heroku addons:add sendgrid:starter
$ heroku config:get SENDGRID_USERNAME
$ heroku config:get SENDGRID_PASSWORD

Check if CarrierWave & S3 are configured (if applicable)

$ heroku config:set S3_ACCESS_KEY=<access key>
$ heroku config:set S3_SECRET_KEY=<secret key>
$ heroku config:set S3_BUCKET=<bucket name>

Destroy the Heroku app and re-create it

$ heroku apps:destroy --app my-app
$ heroku create my-app
$ git push heroku -u master

Claer the asset pipeline cache

$ rake tmp:cache:clear

Masatoshi Nishiguchi