Initial docker release image tooling

Signed-off-by: Erik Hollensbe <github@hollensbe.org>

entrypoint.sh.release

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+grepzt() {
+  (find /proc -name exe | xargs -I{} readlink {}) 2>/dev/null | grep -q zerotier-one
+  return $?
+}
+
+echo "starting zerotier"
+setsid /usr/sbin/zerotier-one &
+
+while ! grepzt
+do
+  echo "zerotier hasn't started, waiting a second"
+  sleep 1
+done
+
+echo "joining networks"
+
+for i in "$@"
+do
+  echo "joining $i"
+
+  while ! zerotier-cli join "$i"
+  do 
+    echo "joining $i failed; trying again in 1s"
+    sleep 1
+  done
+done
+
+sleep infinity