Template google analytics data

Without this patch, the index.html contains google analytics at
all times, including for people self-hosting it.

This is a problem for privacy reasons, and only people wanting
to have analytics on their instances should be able to enable
them.

This fixes it by making sure the index.html page is templated
to sideload content from ANALYTICS_CODE_PATH (which itself is
also templated, for convenience).

front/templater.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -x
+set -o nounset errexit
+template_file_index=dist/index.html.tmpl
+generated_file_index=dist/index.html
+tmp_trackcodefile=/tmp/trackcode
+
+# To inject tracking code, you have two choices:
+# 1) Template using the provided google analytics
+# 2) Insert with your own provided code, by overriding the ANALYTICS_CODE_PATH
+# The ANALYTICS_CODE_PATH is the location of a file inside the container
+ANALYTICS_CODE_PATH="${ANALYTICS_CODE_PATH:-dist/ga.html.tmpl}"
+
+if [[ "${INSERT_ANALYTICS:-NO}" == "NO" ]]; then
+    echo "" > "${tmp_trackcodefile}"
+fi
+
+# Automatically insert analytics if TRACKING_NUMBER is set
+if [[ "${TRACKING_NUMBER:-}" != ""  || "${INSERT_ANALYTICS:-NO}" != "NO" ]]; then
+    echo "Templating code from ${ANALYTICS_CODE_PATH}"
+    sed "s#<!-- TRACKING NUMBER -->#${TRACKING_NUMBER:-}#g" "${ANALYTICS_CODE_PATH}" > "$tmp_trackcodefile"
+fi
+
+echo "Templating ${generated_file_index} from ${template_file_index}"
+sed "/<!-- TRACK CODE -->/r ${tmp_trackcodefile}" "${template_file_index}" > "${generated_file_index}"
+rm "${tmp_trackcodefile}"