1 files changed, 32 insertions, 0 deletions
diff --git a/control/keyfallback/keyfallback.go b/control/keyfallback/keyfallback.go
new file mode 100644
index 000000000..44a190f69
--- /dev/null
+++ b/control/keyfallback/keyfallback.go
@@ -0,0 +1,32 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package keyfallback contains a fallback mechanism for starting up Tailscale
+// when the control server cannot be reached to obtain the primary Noise key.
+//
+// The data is backed by a JSON file `control-key.json` that is updated by
+// `update.go`:
+//
+//	(cd control/keyfallback; go run update.go)
+package keyfallback
+
+import (
+	_ "embed"
+	"encoding/json"
+
+	"tailscale.com/tailcfg"
+)
+
+// Get returns the fallback control server public key that was baked into the
+// binary at compile time. It is only valid for the main Tailscale control
+// server instance.
+func Get() (*tailcfg.OverTLSPublicKeyResponse, error) {
+	out := &tailcfg.OverTLSPublicKeyResponse{}
+	if err := json.Unmarshal(controlKeyJSON, out); err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+//go:embed control-key.json
+var controlKeyJSON []byte