Rename coordinator to bootstrapper and rename roles

bootstrapper/internal/nodelock/nodelock.go

@@ -0,0 +1,25 @@
+package nodelock
+
+import "sync"
+
+// Lock locks the node once there the join or the init is at a point
+// where there is no turning back and the other operation does not need
+// to continue.
+//
+// This can be viewed as a state machine with two states: unlocked and locked.
+// There is no way to unlock, so the state changes only once from unlock to
+// locked.
+type Lock struct {
+	mux *sync.Mutex
+}
+
+// New creates a new NodeLock, which is unlocked.
+func New() *Lock {
+	return &Lock{mux: &sync.Mutex{}}
+}
+
+// TryLockOnce tries to lock the node. If the node is already locked, it
+// returns false. If the node is unlocked, it locks it and returns true.
+func (n *Lock) TryLockOnce() bool {
+	return n.mux.TryLock()
+}