Add bin/gcloud wrapper script

Makefile

@@ -9,7 +9,7 @@ GCLOUD_PROJECT ?= httpbingo
 GCLOUD_ACCOUNT ?= mccutchen@gmail.com
 
 # Run gcloud in a container to avoid needing to install the SDK locally
-GCLOUD_COMMAND ?= docker run --rm -ti --workdir /code -v $$PWD:/code -v $$HOME/.config/gcloud:/root/.config/gcloud google/cloud-sdk gcloud
+GCLOUD_COMMAND ?= ./bin/gcloud
 
 # Built binaries will be placed here
 DIST_PATH  	  ?= dist

bin/gcloud

+#!/bin/bash
+#
+# A wrapper that executes the gcloud CLI in a docker container, to avoid
+# requiring a local installation.
+#
+# Adapted from this helpful blog post:
+# https://blog.scottlowe.org/2018/09/13/running-gcloud-cli-in-a-docker-container/
+
+exec docker run \
+    --rm \
+    -ti \
+    --workdir /code \
+    -v $PWD:/code \
+    -v $HOME/.config/gcloud:/root/.config/gcloud \
+    google/cloud-sdk gcloud $*