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Puma-dev: A fast, zero-config development server for macOS and Linux


Puma-dev is the emotional successor to pow. It provides a quick and easy way to manage apps in development on macOS and Linux.


  • Easy startup and idle shutdown of rack/rails apps
  • Easy access to the apps using the .test subdomain (configurable)
  • Run multiple custom domains at the same time, e.g. .test, .puma.

Why choose puma-dev?

  • https - it Just Works!
  • Supports Rails 5 actioncable via rack.hijack websockets
  • Supports macOS and Linux
  • The venerable pow is no longer maintained


First, ensure that the puma gem is installed. It probably belongs in the Gemfile of the application(s) you're trying to serve via puma-dev.

# Gemfile
gem 'puma'

Homebrew on macOS or GNU/Linux

brew install puma/puma/puma-dev

Pre-built Binaries

You may download binaries for macOS and Linux at

Build from Source

#!/usr/bin/env bash

go version

go get
cd $GOPATH/src/
make && make install

$GOBIN/puma-dev -V

macOS Support

Install & Setup

# Configure some DNS settings that have to be done as root
sudo puma-dev -setup
# Configure puma-dev to run in the background on ports 80 and 443 with the domain `.test`.
puma-dev -install

If you wish to have puma-dev use a port other than 80, pass it via the -install-port, for example to use port 81: puma-dev -install -install-port 81.

NOTE: If you installed puma-dev v0.2, please run sudo puma-dev -cleanup to remove firewall rules that puma-dev no longer uses (and will conflict with puma-dev working).

NOTE: If you had pow installed before in the system, please make sure to run pow's uninstall script. Read more details in the pow manual.


Run: puma-dev -uninstall

NOTE: If you passed custom options (e.g. -d test:localhost) to -setup, be sure to pass them to -uninstall as well. Otherwise /etc/resolver/* might contain orphaned entries.


When puma-dev is installed as a user agent (the default mode), it will log output from itself and the apps to ~/Library/Logs/puma-dev.log. You can refer to there to find out if apps have started and look for errors.

In the future, puma-dev will provide an integrated console for this log output.

Linux Support

Puma-dev supports Linux but requires the following additional installation steps to be followed to make all the features work (-install and -setup flags for Linux are not provided):

puma-dev root CA

The puma-dev root CA is generated (in ~/.puma-dev-ssl/), but you will need to install and trust this as a Certificate Authority by adding it to your operating system's certificate trust store, or by trusting it directly in your favored browser (as some browsers will not share the operating system's trust store).

First, start puma-dev to generate a CA certificate into ~/.puma-dev-ssl/cert.pem.

For Arch Linux, Fedora and other distributions using p11-kit, try this:

# convert from PEM to DER
openssl x509 -in ~/.puma-dev-ssl/cert.pem -outform der -out ~/.puma-dev-ssl/cert.crt

# store certificate as an anchor in the trust policy store
sudo trust anchor --store ~/.puma-dev-ssl/cert.crt

# verify
trust list --filter=ca-anchors | grep -i -C2 Puma-dev

For Debian, Ubuntu etc, try this:

sudo mkdir -p /usr/local/share/ca-certificates
sudo cp ~/.puma-dev-ssl/cert.pem /usr/local/share/ca-certificates/puma-dev-pem.crt
sudo update-ca-certificates

Domains (.test or similar)

In order for requests to the .test (or any other custom) domain to resolve, install the dev-tld-resolver, making sure to use test (or the custom TLD you want to use) when configuring TLDs.

Port 80/443 binding

Linux prevents applications from binding to ports lower that 1024 by default. You don't need to bind to port 80/443 to use puma-dev but it makes using the .test domain much nicer (e.g. you'll be able to use the domain as-is in your browser rather than providing a port number)

There are 2 options to allow puma-dev to listen on port 80 and 443:

  1. Give puma-dev the capabilities directly:
sudo setcap CAP\_NET\_BIND\_SERVICE=+eip /path/to/puma-dev

or 2. Install authbind. and invoke puma-dev with it when you want to use it e.g.

authbind puma-dev -http-port 80 -https-port 443

There is a shortcut for binding to 80/443 by passing -sysbind to puma-dev when starting, which overrides -http-port and -https-port.

Systemd (running puma-dev in the background)

On Linux, puma-dev will not automatically run in the background (as per the MacOS -install script); you'll need to run it in the foreground. You can set up a system daemon to start up puma-dev in the background yourself.

  1. Create /lib/systemd/system/puma-dev.service and put in the following:

ExecStart=/path/to/puma-dev -sysbind


Replace path/to/puma-dev with an absolute path to puma-dev Replace the $USER variable with the name of the user you want to run under.

  1. Start puma-dev using systemd:
sudo systemctl daemon-reload
sudo systemctl enable puma-dev
sudo systemctl start puma-dev


Simply symlink your app's directory into ~/.puma-dev! That's it!

You can use the built-in helper subcommand: puma-dev link [-n name] [dir] to link app directories into your puma-dev directory (~/.puma-dev by default).


Run: puma-dev -h

You have the ability to configure most of the values that you'll use day-to-day.

Advanced Configuration

Puma-dev supports loading environment variables before puma starts. It checks for the following files in this order:

  • ~/.powconfig
  • .env
  • .powrc
  • .powenv
  • .pumaenv

You can prevent puma-dev from loading any of these environment files by setting a corresponding environment variable to '0':


Additionally, puma-dev uses a few other environment variables to control how puma is started that you can overwrite in your loaded shell config.

  • CONFIG: A puma configuration file to load, usually something like config/puma-dev.rb. Defaults to no config.
  • THREADS: How many threads puma should use concurrently. Defaults to 5.
  • WORKERS: How many worker processes to start. Defaults to 0, meaning only use threads.

Important Note On Ports and Domain Names

  • Default privileged ports are 80 and 443
  • Default domain is .test.
    • Previously it was .dev, but it is owned by Google and since Dec 2017 HSTS only with real websites hosted there.
    • Don't use .dev and .foo, as they are real TLDs.
  • Using pow? To avoid conflicts, use different ports and domain or uninstall pow properly.


If you would like to have puma-dev restart a specific app, you can run touch tmp/restart.txt in that app's directory.


If you would like to have puma-dev stop all the apps (for resource issues or because an app isn't restarting properly), you can send puma-dev the signal USR1. The easiest way to do that is:

puma-dev -stop

Running in the foreground

Run: puma-dev

Puma-dev will startup by default using the directory ~/.puma-dev, looking for symlinks to apps just like pow. Drop a symlink to your app in there as: cd ~/.puma-dev; ln -s /path/to/my/app test. You can now access your app as test.test.

Running puma-dev in this way will require you to use the listed http port, which is 9280 by default.

Coming from v0.2

Puma-dev v0.3 and later use launchd to access privileged ports, so if you installed v0.2, you'll need to remove the firewall rules.

Run: sudo puma-dev -cleanup

Coming from Pow

By default, puma-dev uses the domain .test to manage your apps. If you want to have puma-dev look for apps in ~/.pow, just run puma-dev -pow.

Sub Directories

If you have a more complex set of applications you want puma-dev to manage, you can use subdirectories under ~/.puma-dev as well. This works by naming the app with a hyphen (-) where you'd have a slash (/) in the hostname. So for instance if you access cool-frontend.test, puma-dev will look for ~/.puma-dev/cool-frontend and if it finds nothing, try ~/.puma-dev/cool/frontend.

Proxy support

Puma-dev can also proxy requests from a nice dev domain to another app. To do so, just write a file (rather than a symlink'd directory) into ~/.puma-dev with the connection information.

For example, to have port 9292 show up as awesome.test: echo 9292 > ~/.puma-dev/awesome.

Or to proxy to another host: echo > ~/.puma-dev/awesome-elsewhere.


Puma-dev automatically makes the apps available via SSL as well. When you first run puma-dev, it will have likely caused a dialog to appear to put in your password. What happened there was puma-dev generates its own CA certification that is stored in ~/Library/Application Support/

That CA cert is used to dynamically create certificates for your apps when access to them is requested. It automatically happens, no configuration necessary. The certs are stored entirely in memory so future restarts of puma-dev simply generate new ones.

When -install is used (and let's be honest, that's how you want to use puma-dev), then it listens on port 443 by default (configurable with -install-https-port) so you can just do https://blah.test to access your app via https.

Webpack Dev Server

If your app uses HTTPS then the Webpack Dev Server (WDS) should be run via SSL too to avoid browser "Mixed content" errors. While the WDS can generate its own certificates, these expire regularly and often need re-trusting in a new tab to avoid repeating console errors about /sockjs-node/info?t=123 that break the auto-reloading of assets via WDS.

To fix this leave WDS running in plain HTTP mode and combine Puma-dev's proxy and HTTPS features.

Here's how to configure Rails and the Webpacker gem, for an example app already running at https://blah.test:

  • Run echo 3035 > ~/.puma-dev/webpack.blah to set up the proxy to the WDS
  • Edit config/environments/development.rb to include one of the following:
# for webpacker-only projects
config.action_controller.asset_host = '//webpack.blah.test'

# for hybrid webpacker/sprockets projects
config.action_controller.asset_host = proc { |source| '//webpack.blah.test' if source.starts_with?('/packs') }
  • Edit config/webpacker.yml to match:
  https: false
  host: localhost
  port: 3035
  public: webpack.blah.test

You can now restart the app with puma-dev -stop and start WDS with bin/webpack-dev-server.


Puma-dev supports websockets natively but you may need to tell your web framework to allow the connections.

In the case of rails, you need to configure rails to allow all websockets or websocket requests from certain domains. The quickest way is to add config.action_cable.disable_request_forgery_protection = true to config/environments/development.rb. This will allow all websocket connections while in development.

Do not use disable_request_forgery_protection in production!

Or you can add something like config.action_cable.allowed_request_origins = /(\.test$)|^localhost$/ to allow anything under .test as well as localhost.

Puma-dev supports and domains. It will detect them and strip them away, so that your test app can be accessed as

Run multiple domains

Puma-dev allows you to run multiple local domains. Handy if you're working with more than one client. Simply set up puma-dev like so: puma-dev -install -d first-domain:second-domain

Static file support

Like pow, puma-dev support serving static files. If an app has a public directory, then any urls that match files within that directory are served. The static files have priority over the app.

Subdomains support

Once a virtual host is installed, it's also automatically accessible from all subdomains of the named host. For example, a myapp virtual host could also be accessed at http://www.myapp.test/ and http://assets.www.myapp.test/. You can override this behavior to, say, point www.myapp.test to a different application: just create another virtual host symlink named www.myapp for the application you want.

Status API

Puma-dev is starting to evolve a status API that can be used to introspect it and the apps. To access it, send a request with the Host: puma-dev and the path /status, for example: curl -H "Host: puma-dev" localhost/status.

The status includes:

  • If it is booting, running, or dead
  • The directory of the app
  • The last 1024 lines the app output

Events API

Puma-dev emites a number of internal events and exposes them through an events API. These events can be helpful when troubleshooting configuration errors. To access it, send a request with the Host: puma-dev and the path /events, for example: curl -H "Host: puma-dev" localhost/events.


To build puma-dev, follow these steps:

  • Install golang
  • Run go get
  • Run go get
  • Run $GOPATH/bin/puma-dev to use your new binary

Puma-dev uses govendor to manage dependencies, so if you're working on puma-dev and need to introduce a new dependency, run govendor fetch +vendor <package path> to pull it into vendor. Then you can use it from within puma-dev/src

Releasing & Packaging for Homebrew

This script compiles Darwin and Linux binaries, creates a release tag, and uploads the binaries to the release. The Darwin binary can then be referenced in puma/homebrew-puma.

# Gox is a "A dead simple, no frills Go cross compile tool." It's used inside `make release`.
go get -u
# Ghr can be used to "Upload multiple artifacts to GitHub Release in parallel."
go get -u

export OWNER="puma"
export REPO="puma-dev"
export RELEASE="0.13"

make release

git tag -f "v${RELEASE}"
git push origin "v${RELEASE}"

ghr -u $OWNER  -t $GITHUB_TOKEN -r $REPO  -n "v${RELEASE}" -delete -prerelease "v${RELEASE}" ./pkg/