Recompile Heroku slug without push or config change

153
votes

I'm wondering if there is a way to force Heroku to recompile the slug without pushing new commits and/or updating the config variables.

Why would I want to do this?:

I am using the Cedar stack on Heroku for a Rails 3.2 app, and I am having problems with the rake assets:precompile task failing (during compilation only --- later it works fine with a heroku run). I highly suspect this is due to certain environment variables not being available during slug compilation time, and I think the heroku labs:enable user_env_compile experimental feature will solve this.

However, with the user_env_compile feature turned on, config changes do not trigger a recompilation of the slug, and my code hasn't changed, so I don't have any new commits to push.

Of course, I could push a "dummy" commit with a trivial change, which is probably the simplest answer --- but I'm wondering if there's a heroku command that will let me directly recompile the slug.

Thanks!

8
heroku
Nothing in the heroku CLI client? – Matt Ball
Not a direct answer, but it's always wise to document dependency changes like relying on SAAS features, etc. My advise is to add an entry to a CHANGELOG somewhere mentioning you now rely on this feature, and push that change to trigger a rebuild of the slug. – patcoll

8 Answers

97
votes

Slug compilation is invoked with a git pre-recieve hook, so the only way to recompile is to push a new commit.

For completeness see this article on Heroku for the slug compiler. It discussed the use of the pre-recieve hook to invoke the slug compile process under the Compilation heading.

246
votes

The simplest workaround for now is to push an empty commit.

git commit --allow-empty -m "empty commit"
git push heroku master
33
votes

My general approach is to do:

git commit --amend -C HEAD
git push heroku master -f

Not sure I'd do this in production without being certain, as it does technically rewrite the last commit but it shouldn't cause any issues in theory. It's perfectly fine for when you are testing things in staging though.

As an added bonus since most people are problem using Vim to edit commit messages SHIFT-ZZ will quickly save and exit the commit message for you without making any changes to it.

On a related note I'm mildly shocked Heroku still doesn't have this feature. I've often seen Heroku fail to deploy due to problems on their end.

Thanks to Michael Mior for the idea to use -C HEAD to avoid opening up an editor.

20
votes

Heroku have release a plugin that what is asked: https://github.com/heroku/heroku-repo

To install it:

$ heroku plugins:install heroku-repo

To force a rebuild:

$ heroku repo:purge_cache -a appname
$ heroku repo:reset -a appname
$ git push heroku
15
votes

Update: heroku repo:rebuild has been removed.

Heroku has a Build API you can use, see: Building and Releasing Using the API

You can use the repo:rebuild command if the heroku-repo add-on.

heroku repo:rebuild -a appname

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

9
votes

Looks like this is not yet available. However, a feature request has be opened on the heroku github repo

It also mentions "an alternate way to build that is not reliant on git push"

https://github.com/ddollar/heroku-anvil

4
votes

There is a heroku plugin for this.

$ heroku plugins:install heroku-releases-retry
Installing plugin heroku-releases-retry... done
$ heroku releases:retry
Retrying v16 on ⬢ murmuring-lowlands-3398... done, v17
-4
votes

Remove the branch, then re-push it. No need to use a plugin.

git push heroku :master
git push heroku master