aidanhs/secret-server repository overview

⁠docker-secret-server

A really simple (stupid) data server in Docker. Possibly useful for providing secrets to containers during a docker build, but can serve arbitrary files so not necessarily constrained to just that (e.g. you could use it to serve variables at build time to influence your build process). Useful as an initial demonstration of secret sharing that you can extend to anything that exposes a Unix or TCP socket.

As of 1.8, names of containers are automatically inserted into /etc/hosts, so if you run this container with

docker run -d -v /path/to/secrets:/srv/secrets --name dsecret aidanhs/secret-server

where /path/to/secrets is a directory with files containing some data, you can have a Dockerfile like this

FROM myimage

RUN wget -O /getsecret http://dsecret/getsecret && chmod +x /getsecret
ENV SECRET /getsecret dsecret:4444

RUN $SECRET adminpassword | hash_tool | add_password_to_db
RUN $SECRET ssh_key > id_rsa && chmod 600 id_rsa && \
    ssh -T -i id_rsa root@securebox ~/get_data_dump.sh | load_data && \
    rm id_rsa

This is great for temporarily using pieces of data during your build that you don't want to be baked in the final image (SSH keys, signing keys, passwords), particularly if you have a build machine with restricted access - security people sign off code changes, the build is sent to the machine where restricted operations can be performed, operations people take the image knowing there are no secrets hidden in the build for anyone to stumble across.

The secret server exposes two ports:

• port 80 is a http server with secret values available at /secrets/$key and a special /getsecret endpoint giving a static binary for use with...
• port 4444, a plain tcp endpoint. You can hit this with the getsecret binary, netcat (echo adminpassword | nc -q 10 dsecret 4444, where -q 10 is required on Ubuntu 14.04 to make netcat wait for a response) or even bash⁠.

If you get tired of writing SSH keys at the beginning of a step and deleting them at the end, take a look at the SSH agent socket⁠ container.

⁠Security

Running this gives anyone else on your machine access to your 'secrets' directory.

If they have the ability to run arbitrary containers, they already had this.