Ambassadors

Yet another Ambassador pattern over SSH.

Install

You can pull a built container.

$ docker pull jkawamoto/ambassadors

If you are running on Raspberry Pi, you can pull it instead.

$ docker pull jkawamoto/rpi-ambassadors

Usage

$ docker run -dt jkawamoto/ambassadors (server|client|tunnel) [-v]

Options:
  -v           Verbose mode for debugging.

AmbassadorS has three modes; server, client, and tunnel. Those modes are associated as follows.

(a container) ---> (AmbassadorS client) ---> (AmbassadorS tunnel)
              == ssh ==> (AmbassadorS server) ---> (service containers)

You need one server-mode container on a host which has containers to be linked, i.e. service containers, and one tunnel-mode container on each “client” host. You also need client-mode containers for every linking container.

Example

Suppose you have MySQL and MongoDB containers on host A, and a container on host B wants to link them, you firstly need to run a server-mode container linking the MySQL and MongoDB containers on host A.

$ docker run -d --name ambassadors_server \
             -v ~/.ssh/:/data/ -p 10022:22 \
             --link mongo:mongo --link mysql:mysql \
             jkawamoto/ambassadors server

The server-mode container requires authorized_keys in /data/ and to expose port 22 for sshd. In this example, authorized_keys of host A will be used from the server-mode container. The server-mode container also needs to link service containers. In this case, it links to containers named mongo and mysql.

On host B, you need to run a tunnel-mode container.

$ docker run -dt --name ambassadors_tunnel \
            -v ~/.ssh:/root/.ssh -e PORT=10022 -e HOST=<host a> \
            jkawamoto/ambassadors tunnel

The environment variable HOST is the address for host A and PORT is specified the port number of sshd. The tunnel-mode container requires a private key of which the related public key id_rsa is included in the authorized_keys put on the server-mode container. The private key needs to be put in /root/.ssh. In this example, id_rsa of host B will be used from the tunnel-mode container.

You also need to run client-mode containers for MySQL and MongoDB.

$ docker run -d --name mysql_ambassadors \
             --link ambassadors_tunnel:tunnel --expose 3306 -e PORT=3306 \
             jkawamoto/ambassadors client
$ docker run -d --name mongo_ambassadors \
             --link ambassadors_tunnel:tunnel --expose 27017 -e PORT=27017 \
             jkawamoto/ambassadors client

Those client-mode containers must link the tunnel-mode container with name tunnel and expose as same port as service containers expose. In this case, the client-mode container for MySQL exposes 3306 while the mysql container exposes 3306. Those client-mode containers also need to set environment variable PORT as the exposed port number.

Finally, you can use MySQL and MongoDB running on host A from host B.

$ docker run -d --link mysql_ambassadors:mysql --link mongo_ambassadors:mongo some-app

License

This software is released under the MIT License, see LICENSE.