Add infraenv, setup creds and tee for Kitchen.

go/src/infra/libs/infraenv/paths_posix.go

Index: go/src/infra/libs/infraenv/paths_posix.go
diff --git a/go/src/infra/libs/infraenv/paths_posix.go b/go/src/infra/libs/infraenv/paths_posix.go
new file mode 100644
index 0000000000000000000000000000000000000000..ea30540d69752bea3d067d9bd4388268f066edfe
--- /dev/null
+++ b/go/src/infra/libs/infraenv/paths_posix.go
@@ -0,0 +1,16 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd

[nodir, 2016/07/16 00:38:55]

how about
// +build !windows
?

[dnj (Google), 2016/07/16 00:49:39]

I like calling out OSes b/c this means if we ever try to build it for another,
it will fail rather than build unintentionally.

[nodir, 2016/07/16 00:59:32]

i thought only windows is not posix-compliant

[dnj (Google), 2016/07/16 01:06:18]

It's less about compliance and more about which platforms we explicitly have
credentials paths deployed on.

+
+package infraenv
+
+var (
+	// Paths on the system where credentials are stored.
+	//
+	// This path is provisioned by Puppet.
+	systemCredentialDirs = []string{
+		"/creds/service_accounts",
+	}
+)