feat(cache): add Cloudflare SigV4 S3 signature compatibility fix and compile locally

go-cache-plugin-src/cmd/go-cache-plugin/addca_default.go

@@ -0,0 +1,29 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !linux
+
+package main
+
+import (
+	"errors"
+	"log"
+
+	"github.com/creachadair/atomicfile"
+	"github.com/creachadair/command"
+	"github.com/creachadair/tlsutil"
+)
+
+func installSigningCert(env *command.Env, cert tlsutil.Certificate) error {
+	const certFile = "revproxy-ca.crt"
+	if err := atomicfile.WriteData(certFile, cert.CertPEM(), 0644); err != nil {
+		log.Printf("WARNING: Unable to write cert file: %v", err)
+	} else {
+		log.Printf("Wrote signing cert to %s", certFile)
+	}
+	// TODO(creachadair): Maybe crib some other cases from mkcert, if we need
+	// them, for example:
+	// https://github.com/FiloSottile/mkcert/blob/master/truststore_darwin.go
+
+	return errors.New("unable to install a certificate on this system")
+}