Improved bin/heroku/deploy script supports tags etc

bin/heroku/deploy

-#!/bin/bash
+#!/usr/bin/env bash
+
 set -euo pipefail
 
+if [ $# -gt 0 ] && [ "$1" == "-h" ]; then
+    cat <<EOM
+Usage:
+
+Deploy current branch to Heroku app "metabase-CURRENT_BRANCH_NAME"
+
+    ./bin/heroku/deploy
+
+Deploy current branch to Heroku app "HEROKU_APP_NAME"
+
+    ./bin/heroku/deploy "HEROKU_APP_NAME"
+
+Deploy "GIT_REF" (branch or tag) to Heroku app "HEROKU_APP_NAME"
+
+    ./bin/heroku/deploy "HEROKU_APP_NAME" "GIT_REF"
+
+EOM
+    exit 0
+fi
+
 if [ $# -gt 0 ]; then
     heroku_app_name="$1"
 else
+    if [ $(git rev-parse --abbrev-ref HEAD) == "HEAD" ]; then
+        echo "Detached HEAD. Specify a Heroku app name."
+        echo ""
+        echo "For more usage examples: $0 -h"
+        exit 1
+    fi
     heroku_app_name="metabase-$(git rev-parse --abbrev-ref HEAD)"
 fi
 
+if [ $# -gt 1 ]; then
+    # "peel" annotated tags etc
+    git_local_ref="+$2^{}"
+else
+    git_local_ref="HEAD"
+fi
+
+# use explicit "master" ref in case it doesn't exist yet
+git_remote_ref="refs/heads/master"
+
 if ! heroku ps -a "$heroku_app_name" > /dev/null; then
     heroku apps:create -n --addons "heroku-postgresql:hobby-dev" "$heroku_app_name"
     heroku buildpacks:clear -a "$heroku_app_name"
@@ -14,6 +51,7 @@ if ! heroku ps -a "$heroku_app_name" > /dev/null; then
     heroku buildpacks:add "https://github.com/heroku/heroku-buildpack-clojure" -a "$heroku_app_name"
 fi
 
-time git push -f "https://git.heroku.com/$heroku_app_name.git" HEAD:master
+echo git push -f "https://git.heroku.com/$heroku_app_name.git" "$git_local_ref:$git_remote_ref"
+time git push -f "https://git.heroku.com/$heroku_app_name.git" "$git_local_ref:$git_remote_ref"
 
 heroku open -a "$heroku_app_name"