This project is used to show how OPA can help policy-enable an existing service.

In this example, we policy-enable the authorization functionality available in Docker 1.10 and later.

See the detailed example to setup a running example of this plugin.

To build the plugin, just run:

$ go get ./...
$ go build -o docker-authz-plugin

This assumes you are running on Linux and have Go 1.6 or later on your machine. You must have $GOPATH set.

If you are running on OS X and want to cross compile for Linux, you can do so as follows:

$ docker run -it --rm -v $PWD:/go/src/github.com/open-policy-agent/docker-authz-plugin golang:1.6 bash
$ cd /go/src/github.com/open-policy-agent/docker-authz-plugin/
$ go get ./...
$ go build -o docker-authz-plugin
$ exit

The plugin can be started with no options. It may require sudo depending on your machine's Docker configuration permissions:

$ docker-authz-plugin

• By default, the plugin will listen for requests (from Docker) on :8080 and contacts OPA on :8181.

The following command line argument enables the authorization plugin within Docker:

--authorization-plugin=docker-authz-plugin

On Ubuntu 16.04 this is done by overriding systemd configuration (requires root):

$ sudo mkdir -p /etc/systemd/system/docker.service.d
$ sudo tee -a /etc/systemd/system/docker.service.d/override.conf > /dev/null <<EOF
[Service]
ExecStart=
ExecStart=/usr/bin/docker daemon -H fd:// --authorization-plugin=docker-authz-plugin
EOF
$ sudo systemctl daemon-reload
$ sudo service docker restart

The plugin will upsert a policy definition (by default, "example.rego") into OPA on startup and then establish a file watch to be notified when the definition changes. Each time the definition changes, the plugin will upsert into OPA.