---
title: How To Reduce a Large Heroku Slug Size
teaser: 'How to fix the "Compiled slug size: 500.6M is too large (max is 500M)" error
  when trying to deploy your Heroku app.

  '
tags: heroku,ruby,web
author: Dan Croak
published_on: 2016-06-13
---

Have you ever seen this error when you tried to deploy to your Heroku app?

> Compiled slug size: 500.6M is too large (max is 500M)

You can't deploy but don't fret. Here's a few ways to reduce the slug size.

## Clean up the Git repository

Install the [Heroku Repo plugin][repo]:

[repo]: https://github.com/heroku/heroku-repo

<kbd>heroku plugins:install heroku-repo</kbd>

Then run:

<kbd>
heroku repo:gc --app your-app-name
<br />
heroku repo:purge_cache --app your-app-name
</kbd>

These commands will execute `git gc --agressive` ([git-clean]) and
delete the contents of the Heroku build cache stored in
your application's Git repository.

[git-clean]: https://git-scm.com/docs/git-clean

Doing this on a recent app reduced my slug size by 100M.

## Move some files out of the repo

Move internal design documents (`.sketch` files) somewhere like Dropbox. Move
user-facing media (`.mp3`, `.mpg` files) somewhere like Amazon S3.

## Ignore some files that have to be in the repo

[Follow Heroku's instructions][slugignore] to
ignore files such as unit tests with `.slugignore`.

[slugignore]: https://devcenter.heroku.com/articles/slug-compiler#ignoring-files-with-slugignore

## Remove unused dependencies

Hopefully each Ruby gem in your [Bundler groups] is being used by the app,
but do a quick audit and remove any that aren't used.

[Bundler groups]: http://bundler.io/v1.5/groups.html

## Bundle only what you need for the environment

Heroku accepts an [environment variable][env]
to limit the Ruby gems you bundle and cache.

[env]: https://devcenter.heroku.com/articles/config-vars

<kbd>heroku config:set BUNDLE_WITHOUT="development:test" --app your-app-name</kbd>

## Avoid Asset Sync

Rails' asset pipeline is a tempting area to try to optimize for slug size.
App stylesheets, scripts, and images add up.

[Asset Sync] is a cool tool to push assets to S3 during pre-compilation but
[Heroku does not recommend it][anti]. So far, I've been able to avoid Asset
Sync.

[Asset Sync]: https://github.com/AssetSync/asset_sync
[anti]: https://devcenter.heroku.com/articles/please-do-not-use-asset-sync

## Good luck!

Hopefully these tips get you deploying again within a few minutes. Good luck!