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Dinghy HTTP Proxy

Docker Automated build

This is the HTTP Proxy and DNS server that Dinghy uses.

The proxy is based on jwilder's excellent nginx-proxy project, with modifications to make it more suitable for local development work.

A DNS resolver is also added. By default it will resolve all *.docker domains to the Docker VM, but this can be changed.


Exposed Ports

The proxy will by default use the first port exposed by your container as the HTTP port to proxy to. This can be overridden by setting the VIRTUAL_PORT environment variable on the container to the desired HTTP port.

Docker Compose Projects

The proxy will auto-generate a hostname based on the docker tags that docker-compose adds to each container. This hostname is of the form <service>.<project>.<tld>. For instance, assuming the default *.docker TLD, a "web" service in a "myapp" docker-compose project will be automatically made available at http://web.myapp.docker/.

Explicitly Setting a Hostname

As in the base nginx-proxy, you can configure a container's hostname by setting the VIRTUAL_HOST environment variable in the container.

You can set the VIRTUAL_HOST environment variable either with the -e option to docker or the environment hash in docker-compose. For instance setting VIRTUAL_HOST=myrailsapp.docker will make the container's exposed port available at http://myrailsapp.docker/.

This will work even if dinghy auto-generates a hostname based on the docker-compose tags.

Multiple Hosts

If you need to support multiple virtual hosts for a container, you can separate each entry with commas. For example,,, and each host will be setup the same.

Additionally you can customize the port for each host by appending a port number:, Each name will point to its specified port and any name without a port will use the default.

Wildcard Hosts

You can also use wildcards at the beginning and the end of host name, like * or*. Or even a regular expression, which can be very useful in conjunction with a wildcard DNS service like, using ~^foo\.bar\..*\.xip\.io will match, and all other given IPs. More information about this topic can be found in the nginx documentation about server_names.

Enabling CORS

You can set the CORS_ENABLED environment variable either with the -e option to docker or the environment hash in docker-compose. For instance setting CORS_ENABLED=true will allow the container's web proxy to accept cross domain requests.

If you want to be more specific, you can also set CORS_DOMAINS (along with CORS_ENABLED) to specify the domains you want to whitelist. They need to be separated using comma.

This is especially helpful when you have to deal with CORS with authenticated cross domain requests.

More information on this topic on MDN.

Subdomain Support

If you want your container to also be available at all subdomains to the given domain, prefix a dot . to the provided hostname. For instance setting VIRTUAL_HOST=.myrailsapp.docker will also make your app avaiable at *.myrailsapp.docker.

This happens automatically for the auto-generated docker-compose hostnames.

SSL Support

SSL is supported using single host certificates using naming conventions.

To enable SSL, just put your certificates and privates keys in the HOME/.dinghy/certs directory for any virtual hosts in use. The certificate and keys should be named after the virtual host with a .crt and .key extension. For example, a container with should have a and file in the certs directory.

How SSL Support Works

The SSL cipher configuration is based on mozilla nginx intermediate profile which should provide compatibility with clients back to Firefox 1, Chrome 1, IE 7, Opera 5, Safari 1, Windows XP IE8, Android 2.3, Java 7. The configuration also enables HSTS, and SSL session caches.

The default behavior for the proxy when port 80 and 443 are exposed is as follows:

  • If a container has a usable cert, port 80 will redirect to 443 for that container so that HTTPS is always preferred when available.
  • If the container does not have a usable cert, port 80 will be used.

To serve traffic in both SSL and non-SSL modes without redirecting to SSL, you can include the environment variable HTTPS_METHOD=noredirect (the default is HTTPS_METHOD=redirect). You can also disable the non-SSL site entirely with HTTPS_METHOD=nohttp.

How to quickly generate self-signed certificates

You can generate self-signed certificates using openssl.

openssl req -x509 -newkey rsa:2048 -keyout \
-out -days 365 -nodes \
-subj "/C=US/ST=Oregon/L=Portland/O=Company Name/OU=Org/" \
-config <(cat /etc/ssl/openssl.cnf <(printf "[SAN]\")) \
-reqexts SAN -extensions SAN

To prevent your browser to emit warning regarding self-signed certificates, you can install them on your system as trusted certificates.

Using Outside of Dinghy

Since this functionality is generally useful for local development work even outside of Dinghy, this proxy now supports running standalone.

Environment variables

We include a few environment variables to customize the proxy / dns server:

  • DOMAIN_TLD default: docker - The DNS server will only respond to *.docker by default. You can change this to dev if it suits your workflow
  • DNS_IP default: - Setting this variable is explained below


You'll need the IP of your VM:

  • For docker-machine, run docker-machine ip <machine_name> to get the IP.
  • For Docker for Mac, you can use as the IP, since it forwards docker ports to the host machine.

Then start the proxy:

docker run -d --restart=always \
  -v /var/run/docker.sock:/tmp/docker.sock:ro \
  -v ~/.dinghy/certs:/etc/nginx/certs \
  -p 80:80 -p 443:443 -p 19322:19322/udp \
  -e DNS_IP=<vm_ip> -e CONTAINER_NAME=http-proxy \
  --name http-proxy \

You will also need to configure OS X to use the DNS resolver. To do this, create a file /etc/resolver/docker (creating the /etc/resolver directory if it does not exist) with these contents:

nameserver <vm_ip>
port 19322

You only need to do this step once, or when the VM's IP changes.


For running Docker directly on a Linux host machine, the proxy can still be useful for easy access to your development environments. Similar to OS X, start the proxy:

docker run -d --restart=always \
  -v /var/run/docker.sock:/tmp/docker.sock:ro \
  -v ~/.dinghy/certs:/etc/nginx/certs \
  -p 80:80 -p 443:443 -p 19322:19322/udp \
  -e CONTAINER_NAME=http-proxy \
  --name http-proxy \

The DNS_IP environment variable is not necessary when Docker is running directly on the host, as it defaults to

Different Linux distributions will require different steps for configuring DNS resolution. The Dory project may be useful here, it knows how to configure common distros for dinghy-http-proxy.


  • For Docker for Windows, you can use as the DNS IP.

From Powershell:

docker run -d --restart=always `
  -v /var/run/docker.sock:/tmp/docker.sock:ro `
  -p 80:80 -p 443:443 -p 19322:19322/udp `
  -e CONTAINER_NAME=http-proxy `
  -e DNS_IP= `
  --name http-proxy `

From docker-compose:

version: '2'

    container_name: http-proxy
    image: codekitchen/dinghy-http-proxy
      - DNS_IP=
      - CONTAINER_NAME=http-proxy
      - "80:80"
      - "443:443"
      - "19322:19322/udp"
      - /var/run/docker.sock:/tmp/docker.sock:ro

You will have to add the hosts to C:\Windows\System32\drivers\etc\hosts manually. There are various Powershell scripts available to help manage this: