Asset Pipeline issue on Heroku

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Rails
2012-06-08 · 1 min read

On Heroku application's config variables are not present in the environment during the slug compilation. Sometimes however certain variables are needed at that stage. For example, as deployment goes through rake assets:precompile step, you may need to connect to your database, otherwise you will get an error similar to the following:

----->  Preparing app for Rails asset pipeline
        Running: rake assets:precompile
        rake aborted!
        could not connect to server: Connection refused
        Is the server running on host "127.0.0.1" and accepting
        TCP/IP connections on port 5432?

The solution is to use Heroku Labs feature called user_env_compile which puts config vars in the environment at slug compilation stage.

It can be enabled like so:

heroku labs:enable user_env_compile -a myapp

That should resolve the problem with the rake assets:precompile execution.