Subway

Automatically create Cloudflare Tunnels for Docker containers.

Inspired by: https://github.com/aschzero/hera

How It Works

Subway connects to the Docker daemon, and if a container with a subway.hostname label is running, started or stopped the tunnel and associated DNS will be updated automatically.

It will create a tunnel called Subway, and for hostnames specified in the label subway.hostname it will create a DNS mapping in the cloudflare DNS to the tunnel UUID.

Current Status

It works, but it's rough (it's a bash script!), I built it for personal use, your mileage may vary.

Using

Start Subway:

docker run \
	--name=Subway
	-v /var/run/docker.sock:/var/run/docker.sock \
	-v '/path/to/data':'/data':'rw' \
	mikeburgh/subway:latest

On first run check the docker logs for the authorization url, and copy it to a browser to complete authorization.
Assign subway.hostname and subway.port labels to containers you want to access via the tunnel and then restart them for Subway to notice the change.

External Services

If you have other services outside of docker containers, Subway can manage those provided it can access the service.

To add an extra service, use the EXTERNAL_SERVICES environment variable with a JSON array of hostname and service definitions, eg:

[
	{ "hostname": "site1.example.com", "service": "http://10.1.1.1:8080" },
	{ "hostname": "site2.example.com", "service": "http://10.1.1.2:8080" }
]

The JSON also supports originRequest configuration as detailed in Advanced Configuration

For example:

[{ "hostname": "site3.example.com", "service": "http://10.1.1.3:8080", "originRequest": { "noTLSVerify": true, "httpHostHeader": "another-site.example.com" } }]

An example of running Subway with two external services configured

docker run \
	--name=Subway
	-v /var/run/docker.sock:/var/run/docker.sock \
	-v '/path/to/data':'/data':'rw' \
	-e 'EXTERNAL_SERVICES'='[{ "hostname": "site1.example.com", "service": "http://10.1.1.1:8080" },{ "hostname": "site2.example.com", "service": "http://10.1.1.2:8080" }]'
	mikeburgh/subway:latest

Important notes

Docker.sock is required so it can watch for changes
Data volume is required to persist authorization
The domain you select to authorize is the only one you can use in the label.hostnames.
The subway container must be able to communicate with the containers with subway labels, you may need to create a dedicated network for subway and bridge it place Subway and other containers in it.

Todo

Option to expose it's metrics, if hostname on the container
Delete dns records of stopped containers (may require functionality from Cloudflare)
Better handle if tunnel name exists
Expose tunnel name as a docker ENV
Support private network routing
Restart cloudflared if it stops
Support multiple domains (may require multiple tunnels)

To Build

docker build -t mikeburgh/subway:latest .

mstofflett/subway