Docker-dev: A fork of puma-dev for containerized apps

Docker-dev is a fork of puma-dev that eschews the dependence on Rack applications and focuses on proxying requests only. Instead of assuming that the application you want to serve is a Rack app, docker-dev assumes you're running the app in Docker, and runs docker-compose up to boot your app. A special environment variable named $PORT is passed into docker-compose to determine which port in your Docker application the server will proxy requests to. You can expose this port in your compose file's :ports declaration and view your projects at an easy to remember domain, with no configuration!

Highlights

• 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, .docker.

Why choose docker-dev?

• https - it Just Works!
• Supports macOS and Linux
• The honorary pow is no longer maintained
• puma-dev requires custom configuration to use with containerized applications.

Installation

Install docker-dev using a pre-built binary...

One-Line Install Script

$ curl -sL https://tubbo.github.io/install.sh | bash

Pre-built Binaries

You may download binaries for macOS and Linux at https://github.com/tubbo/docker-dev/releases

Build from Source

$ git clone https://github.com/tubbo/docker-dev.git
$ cd docker-dev
$ make && make install
$ docker-dev -V

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macOS Support

Install & Setup

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

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

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

If you're currently using pow or puma-dev, docker-dev taking control of .test will break it. If you want to just try out docker-dev and leave pow working, pass -d docker on -install to use the .docker as an alternate development TLD.

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.

Uninstall

Run: docker-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.

Logging

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

In the future (probably whenever puma-dev adds it), docker-dev will provide an integrated console for this log output.

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Linux Support

docker-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):

docker-dev root CA

The docker-dev root CA is generated (in ~/.docker-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).

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 docker-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 docker-dev to listen on port 80 and 443:

1. Give docker-dev the capabilities directly:

sudo setcap CAP\_NET\_BIND\_SERVICE=+eip /path/to/docker-dev

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

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

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

Systemd (running docker-dev in the background)

On Linux, docker-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 docker-dev in the background yourself.

First, create /lib/systemd/system/docker-dev.service and put in the following:

[Unit]
After=network.target

[Service]
User=$USER
ExecStart=/path/to/docker-dev -sysbind
Restart=on-failure

[Install]
WantedBy=multi-user.target

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

Youc an now start docker-dev using systemd:

sudo systemctl daemon-reload
sudo systemctl enable docker-dev
sudo systemctl start docker-dev

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Usage

When you request your application via the .test domain, docker-dev will launch docker-compose in the root directory of your app and proxy connections to a random port in the 3001-3999 range. This port is different every time, so it can't be hardcoded into a project's configuration. Instead, docker-dev passes this randomly generated port number as $PORT in the environment when launching docker-compose. To send traffic from a container in your services to the domain name when it's requested, make sure the port in your app is exposed as $PORT like so:

version: '3'
services:
  web:
    build: .
    ports:
      - '${PORT:-3000}:3000'

Then, symlink your app's directory into ~/.docker-dev.

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

Options

Run: docker-dev -h

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

Advanced Configuration

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

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

Zero Configuration

It's possible to have docker-dev automatically boot Docker applications when you request them in the browser, based on the folder they are located in on your computer. To do this, remove the ~/.docker-dev directory and symlink it to the directory all of your code lives in, like so (command example is from macOS):

rm -rf ~/.docker-dev && ln -s ~/Code ~/.docker-dev

This alleviates you from having to run link every time you create a new app.

Important Note On Ports and Domain Names

• Default privileged ports are 80 and 443
• Default domain is .test. (don't use .dev and .foo, as they are now real TLDs)
• Using pow or puma-dev? To avoid conflicts, use different ports and domain or uninstall pow properly.

Restarting

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

Purging

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

docker-dev -stop

Running in the foreground

Run: docker-dev

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

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

Coming from Pow

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

Sub Directories

If you have a more complex set of applications you want docker-dev to manage, you can use subdirectories under ~/.docker-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, docker-dev will look for ~/.docker-dev/cool-frontend and if it finds nothing, try ~/.docker-dev/cool/frontend.

Proxy support

docker-dev can also proxy any request from a nice dev domain to another app over a dedicated port number. To do so, just write a file (rather than a symlink'd directory) into ~/.docker-dev with the connection information.

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

Or to proxy to another host: echo 10.3.1.2:9292 > ~/.docker-dev/elsewhere.

HTTPS

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

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 docker-dev simply generate new ones.

When -install is used (and let's be honest, that's how you want to install docker-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.

Websockets

docker-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.

xip.io

docker-dev supports xip.io domains. It will detect them and strip them away, so that your test app can be accessed as test.A.B.C.D.xip.io.

Run multiple domains

docker-dev allows you to run multiple local domains. Handy if you're working with more than one client, or if you're simultaneously running puma-dev on the same machine. Simply set up docker-dev like so: docker-dev -install -d first-domain:second-domain

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

docker-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: docker-dev header and the path /status, for example: curl -H "Host: docker-dev" localhost/status.

The status includes:

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

Development

To build docker-dev, follow these steps:

• Install golang
• Run make
• Run ./docker-dev to use your new binary

docker-dev uses Go Modules to manage dependencies, so you must be running v1.11 or above.