Disable IPv6 default for npm

build.sh

@@ -1,7 +1,11 @@
 #!/bin/bash
 
-npm install -Dy
-npm -y exec webpack
+# Concourse Worker doesn't support IPv6 well yet.
+function npm-ipv4() {
+    node --dns-result-order=ipv4first $(which npm) $*
+}
+npm-ipv4 install -Dy
+npm-ipv4 -y exec webpack
 cp ./node_modules/xterm/css/xterm.css ./assets/
 cp dist/main.js ./assets/main.js
 cd hugo-static