diff --git a/.yarnrc b/.yarnrc
new file mode 100644
index 0000000..d9df855
--- /dev/null
+++ b/.yarnrc
@@ -0,0 +1,5 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+yarn-path ".yarn/releases/yarn-1.22.21.cjs"
diff --git a/build-webapp.sh b/build-webapp.sh
index a77ec64..b22dde5 100755
--- a/build-webapp.sh
+++ b/build-webapp.sh
@@ -9,6 +9,14 @@ if [[ -d "$DEST_DIR" ]]; then
   exit 1
 fi
 
+if [[ -f "$PKG_DIR/.env" ]]; then
+  echo "Using existing .env file"
+else
+  mv "$PKG_DIR/.env.example" "$PKG_DIR/.env"
+  echo "Created .env file. Please populate with the correct values."
+  exit 1
+fi
+
 cat > $PKG_DIR/.env <<EOF
 REACT_APP_SERVER_URL = 'LACONIC_HOSTED_CONFIG_app_server_url'
 REACT_APP_GITHUB_CLIENT_ID = 'LACONIC_HOSTED_CONFIG_app_github_clientid'