Heroku surrogate

The heroku surrogate command pulls down the environment variables for a Heroku application, merges them into the local environment, and spawns a process. Here's a Rails specific example:

heroku surrogate rake db:migrate:up VERSION=20130228193803

This runs the migration locally, but connected to the DATABASE_URL specified by the server. This is great for sneaking a nondestructive migration out before the actual deploy, thus minimizing downtime.

The fun doesn't stop there. You can pass in a process type from your Procfile or any arbitrary command. Spin up a console. Spin up a worker. Heck, spin up a web server if you want.

heroku surrogate console
heroku surrogate worker
heroku surrogate PORT=3000 web

The --release option lets you use the environment and process types from an earlier release.

heroku surrogate --release=v123 env

Note that you're using development code against production resources. If you'd rather be running production code as well, pass --checkout, and the appropriate commit (respecting --release if given) will be checked out before executing.

heroku surrogate --checkout foreman start

Installation

heroku plugins:install https://github.com/tpope/heroku-surrogate.git