Add image build dev script

docs/getting-started.md

@@ -57,6 +57,8 @@ Then on a node:
 PROMENADE_LOAD_IMAGE=/vagrant/promenade.tar bash /vagrant/up.sh /vagrant/path/to/node-config.yaml
 ```
 
+These commands are combined in a convenience script at `tools/dev-build.sh`.
+
 To build the image from behind a proxy, you can:
 
 ```bash

tools/dev-build.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+set -ex
+
+echo === Cleaning up old data ===
+rm -rf promenade.tar configs
+mkdir configs
+
+echo === Building image ===
+docker build -t quay.io/attcomdev/promenade:latest .
+
+echo === Generating updated configuration ===
+docker run --rm -t \
+    -v $(pwd):/target quay.io/attcomdev/promenade:latest \
+        promenade -v \
+            generate \
+                -c /target/example/vagrant-input-config.yaml \
+                -o /target/configs
+
+echo === Saving image ===
+docker save -o promenade.tar quay.io/attcomdev/promenade:latest
+
+echo === Done ===