feature/appconnectors: start making it modular

Saves 45 KB.

Updates #12614

Change-Id: Iaeb73e69633878ce0a0f58c986024784bbe218f1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

feature/appconnectors/appconnectors.go

@@ -0,0 +1,39 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package appconnectors registers support for Tailscale App Connectors.
+package appconnectors
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"tailscale.com/ipn/ipnlocal"
+	"tailscale.com/tailcfg"
+)
+
+func init() {
+	ipnlocal.RegisterC2N("GET /appconnector/routes", handleC2NAppConnectorDomainRoutesGet)
+}
+
+// handleC2NAppConnectorDomainRoutesGet handles returning the domains
+// that the app connector is responsible for, as well as the resolved
+// IP addresses for each domain. If the node is not configured as
+// an app connector, an empty map is returned.
+func handleC2NAppConnectorDomainRoutesGet(b *ipnlocal.LocalBackend, w http.ResponseWriter, r *http.Request) {
+	logf := b.Logger()
+	logf("c2n: GET /appconnector/routes received")
+
+	var res tailcfg.C2NAppConnectorDomainRoutesResponse
+	appConnector := b.AppConnector()
+	if appConnector == nil {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(res)
+		return
+	}
+
+	res.Domains = appConnector.DomainRoutes()
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(res)
+}

feature/buildfeatures/feature_appconnectors_disabled.go

@@ -0,0 +1,13 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by gen.go; DO NOT EDIT.
+
+//go:build ts_omit_appconnectors
+
+package buildfeatures
+
+// HasAppConnectors is whether the binary was built with support for modular feature "App Connectors support".
+// Specifically, it's whether the binary was NOT built with the "ts_omit_appconnectors" build tag.
+// It's a const so it can be used for dead code elimination.
+const HasAppConnectors = false

feature/buildfeatures/feature_appconnectors_enabled.go

@@ -0,0 +1,13 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by gen.go; DO NOT EDIT.
+
+//go:build !ts_omit_appconnectors
+
+package buildfeatures
+
+// HasAppConnectors is whether the binary was built with support for modular feature "App Connectors support".
+// Specifically, it's whether the binary was NOT built with the "ts_omit_appconnectors" build tag.
+// It's a const so it can be used for dead code elimination.
+const HasAppConnectors = true

feature/condregister/maybe_appconnectors.go

@@ -0,0 +1,8 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !ts_omit_appconnectors
+
+package condregister
+
+import _ "tailscale.com/feature/appconnectors"

feature/featuretags/featuretags.go

@@ -88,6 +88,7 @@ type FeatureMeta struct {
 // excluded via build tags, and a description of each.
 var Features = map[FeatureTag]FeatureMeta{
 	"acme":          {"ACME", "ACME TLS certificate management", nil},
+	"appconnectors": {"AppConnectors", "App Connectors support", nil},
 	"aws":           {"AWS", "AWS integration", nil},
 	"bird":          {"Bird", "Bird BGP integration", nil},
 	"captiveportal": {"CaptivePortal", "Captive portal detection", nil},