Add support for current build command

This lets us easily inspect what version Heimdall has deployed. The
number is a link to the Circle build, as well.

.circleci/config.yml

@@ -33,7 +33,9 @@ jobs:
             gcloud --quiet auth configure-docker
       - run:
           name: Build Docker Image
-          command: docker build -t gcr.io/cfc-production/heimdall:$CIRCLE_BUILD_NUM .
+          command: |
+            echo $CIRCLE_BUILD_NUM > BUILD
+            docker build -t gcr.io/cfc-production/heimdall:$CIRCLE_BUILD_NUM .
       - run:
           name: Push Docker Image
           command: docker push gcr.io/${PROJECT_NAME}/heimdall:$CIRCLE_BUILD_NUM

Dockerfile

@@ -14,6 +14,7 @@ RUN mkdir bin scripts
 COPY external-scripts.json .
 COPY bin ./bin
 COPY scripts ./scripts
+COPY BUILD ./BUILD
 
 ENV PATH="node_modules/.bin:node_modules/hubot/node_modules/.bin:$PATH"
 

scripts/current-build.js

@@ -0,0 +1,28 @@
+let fs = require("fs")
+
+// Description:
+//   Returns the current deployed build.
+//
+// Dependencies:
+//   None
+//
+// Commands:
+//   hubot current build
+//
+// Author:
+//   shadowfiend
+
+let buildNumberBuffer = ""
+try {
+    buildNumberBuffer = fs.readFileSync(`${__dirname}/../BUILD`)
+} catch (e) {
+    console.error("Error reading buildNumber file: " + e)
+}
+let buildNumber = buildNumberBuffer.toString()
+
+// TODO Announce new build to Bifrost flow, configured.
+
+module.exports = function (robot) {
+    robot.respond(/current build/, (response) =>
+        response.send(`I'm on build [${buildNumber}](https://circle-ci.com/gh/cardforcoin/heimdall/${buildNumber})!`))
+}