beeffed up the README

Author: ChristianKniep

README.md

@@ -1,2 +1,83 @@
 # doxy
 Docker unix-socket proxy to provide unharmful, read-only API calls
+
+## Usage
+
+```bash
+$ ./doxy_darwin --help
+*snip*
+GLOBAL OPTIONS:
+   --docker-socket value  Docker host to connect to. (default: "/var/run/docker.sock") [$DOXY_DOCKER_SOCKET]
+   --proxy-socket value   Proxy socket to be created (default: "/tmp/doxy.sock") [$DOXY_PROXY_SOCKET]
+   --debug                Print proxy requests [$DOXY_DEBUG]
+   --pattern-file value   File holding line-separated regex-patterns to be allowed (comments allowed, use #) (default: "/etc/doxy.pattern") [$DOXY_PATTERN_FILE]
+   --help, -h             show help
+   --version, -v          print the version
+$ ./doxy_darwin
+2017/08/18 11:37:43 [II] Start Version: 0.1.0
+2017/08/18 11:37:43 Error reading patterns file (open /etc/doxy.pattern: no such file or directory), using default patterns
+2017/08/18 11:37:43 [gk-soxy] Listening on /tmp/doxy.sock
+```
+
+## Filter mechanism
+
+### Request Method
+
+For starters the proxy only allows `GET` requests.
+
+```bash
+$ docker -H unix:///tmp/doxy.sock run ubuntu bash
+docker: Error response from daemon: Only GET requests are allowed, req.Method: POST.
+See 'docker run --help'.
+```
+
+### Regex
+
+Once the method is checked, a list of regular expressions are checked. In version 0.1.0 the list reads:
+
+```bash
+# List and inspect containers
+^/(v\d\.\d+/)?containers(/\w+)?/json$
+# List and inspect services
+^/(v\d\.\d+/)?services(/[0-9a-f]+)?$
+# List and inspect tasks
+^/(v\d\.\d+/)?tasks(/\w+)?$
+# List and inspect networks
+^/(v\d\.\d+/)?networks(/\w+)?$
+# List and inspect nodes
+^/(v\d\.\d+/)?nodes(/\w+)?$
+# Show engine info
+^/(v\d\.\d+/)?info$
+# Healthcheck
+^/_ping$
+```
+
+Thus, an export of a container filesystem is not allowed.
+
+```bash
+$ docker -H unix:///tmp/doxy.sock export -o test.tar $(docker ps -lq)
+Error response from daemon: '/v1.31/containers/a62250e0890a/export' is not allowed.
+```
+
+## Debug output
+
+The tool uses [negroni](https://github.com/urfave/negroni), a nice web middleware in golang.
+When providing the `-debug` flag, the `Logger()` middleware will be added.
+
+```bash
+$ ./doxy_darwin -debug
+2017/08/18 11:44:50 [II] Start Version: 0.1.0
+2017/08/18 11:44:50 Error reading patterns file (open /etc/doxy.pattern: no such file or directory), using default patterns
+2017/08/18 11:44:50 0  : ^/(v\d\.\d+/)?containers(/\w+)?/json$
+2017/08/18 11:44:50 1  : ^/(v\d\.\d+/)?services(/[0-9a-f]+)?$
+2017/08/18 11:44:50 2  : ^/(v\d\.\d+/)?tasks(/\w+)?$
+2017/08/18 11:44:50 3  : ^/(v\d\.\d+/)?networks(/\w+)?$
+2017/08/18 11:44:50 4  : ^/(v\d\.\d+/)?nodes(/\w+)?$
+2017/08/18 11:44:50 5  : ^/(v\d\.\d+/)?info$
+2017/08/18 11:44:50 6  : ^/_ping$
+2017/08/18 11:44:50 [gk-soxy] Listening on /tmp/doxy.sock
+[negroni] 2017-08-18T11:45:00+02:00 | 200 | 	 3.800713ms | docker | GET /_ping
+[negroni] 2017-08-18T11:45:00+02:00 | 403 | 	 34.067µs | docker | GET /v1.31/containers/a62250e0890a/export
+[negroni] 2017-08-18T11:45:04+02:00 | 200 | 	 1.800044ms | docker | GET /_ping
+[negroni] 2017-08-18T11:45:04+02:00 | 200 | 	 2.055015ms | docker | GET /v1.31/containers/json
+```