Docker SSH Tunnel

This is a Docker image used by Disco to create an ad hoc SSH tunnel when the user needs to access services that are not exposed.

As it is, it's just Alpine with OpenSSH installed.

It's configured when it's needed.

The goal of the image is just to speed up the parts that could be slow or unreliable otherwise.

Build and push

docker buildx build \
  --platform linux/amd64,linux/arm64/v8 \
  --tag letsdiscodev/sshtunnel \
  --push \
  .

Usage

This is used internally by Disco, but the concept looks like this.

It creates a temporary container from the image, connected to the Docker network, and publishing a port for SSH, but with a random port instead of 2222, and a random password instead of Password1.

docker run -it --network disco-main --publish 2222:22 --env PASSWORD=Password1 letsdiscodev/sshtunnel

Then the CLI can create an SSH tunnel to, for example, Postgres, with the equivalent of this command:

ssh -L 5432:postgres-instance-pallid-knot-postgres:5432 root@disco.example.com -p 2222

And that's it. Postgres is now accessible from localhost while the tunnel is connected.

For example,

disco env:get DATABASE_URL --project my-project --disco disco.example.com

outputs

postgresql://so72kvhxban57ro9:OYOJ7AbYrUvamTbc@postgres-instance-pallid-knot-postgres/twsoh0a61sc3xfve

so you can connect to this database by replacing postgres-instance-pallid-knot-postgres with localhost

pgcli postgresql://so72kvhxban57ro9:OYOJ7AbYrUvamTbc@localhost/twsoh0a61sc3xfve