testbeds: Add docker testbed

This adds support for a testbed based on Docker containers running on
the local host. Bridging the containers can be done using built-in
Linux bridging or using OpenVSwitch bridges.

A new resource 'executor' has been added to abstract away command
execution on nodes on the testbed. Executors have been created for
local command execution, docker exec based command execution and
SSH-based command execution. This has also been changed in the
prototypes to execute using the correct executor.

1 files changed, 14 insertions, 0 deletions

diff --git a/README.md b/README.md
index 5f42618..6feafbc 100644
--- a/README.md
+++ b/README.md
@@ -160,6 +160,20 @@ Example scripts can be found in the examples/ folder.
    for the previous commands, without changing the user (e.g. using su
    or sudo).
 
+ * [Docker](https://www.docker.com/) is a container runtime environment.
+
+   To use the Docker testbed the Docker software needs to be installed, see
+   [Install Docker](https://docs.docker.com/install/) and complete
+   [Post-installation steps for Linux](https://docs.docker
+   .com/install/linux/linux-postinstall/)
+
+   To use a Docker testbed you can for example use:
+
+        tb = docker.Testbed(exp_name = "ouroboros",
+                            base_image = "ouroborosrumba/prototype")
+
+   This will pull the latest ouroboros image from Docker Hub.
+
 ## Accessing nodes after swap-in
 
    To access a node once the experiment swapped in, use the following