puma-dev is a useful tool for Rails developers. It’s a successor to pow, an older tool by Basecamp.

puma-dev makes it easy to switch between working on multiple Rails apps in a local environment, without dealing with port conflicts. It also spins down idle apps to save resources.

Let’s say you’re working on an app in ~/src/myapp. If you run puma-dev link, it will create a new symlink in ~/.puma-dev/. You can then access your app on your local machine at https://myapp.test, without having to manually start a Rails instance.

With the emergence of AI agents, it’s becoming more common to be working on multiple features concurrently in isolated workspaces by using Git worktrees.

In Conductor you can specify scripts to run when setting up a new workspace or archiving an existing one. We can make use of these to set up puma-dev automatically.

Conductor assigns random names to workspaces (from a list of city names). For the hostname, I prefer to prefix the workspace name with my repo name, e.g. https://myapp-toronto.test.

When a workspace is longer needed, e.g. the feature has been merged, the workspace can be archived, and the symlink will be removed from ~/.puma-dev/.

Here are the scripts that I’m using:

bin/conductor-setup

#!/usr/bin/env ruby
workspace_path = ENV.fetch("CONDUCTOR_WORKSPACE_PATH")
project = File.basename(File.dirname(workspace_path))
name = "#{project}-#{File.basename(workspace_path)}"
system("puma-dev link -n #{name}") or abort "puma-dev link failed"
puts "puma-dev link succeeded: https://#{name}.test"

bin/conductor-archive

#!/usr/bin/env ruby
workspace_path = ENV.fetch("CONDUCTOR_WORKSPACE_PATH")
project = File.basename(File.dirname(workspace_path))
name = "#{project}-#{File.basename(workspace_path)}"
symlink = File.expand_path("~/.puma-dev/#{name}")
File.delete(symlink)

You’ll also need to make each script executable using chmod +x.

To learn more about using Conductor with Rails, check out: