Generate Caddy config

The generated configuration sends all traffic through the dns01proxy
handler. It also configures trusted proxies so that we can get the real
client IP in our logs.

Author: liujed

app.go

@@ -2,8 +2,13 @@ package caddydns01proxy
 
 import (
 	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
 
 	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/caddyconfig"
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
 )
 
 func init() {
@@ -19,9 +24,14 @@ type App struct {
 
 	// Configures the set of trusted proxies.
 	TrustedProxiesRaw json.RawMessage `json:"trusted_proxies,omitempty" caddy:"namespace=http.ip_sources inline_key=source"`
+
+	// The http module instance that implements this app.
+	httpApp *caddyhttp.App `json:"-"`
 }
 
 var _ caddy.Module = (*App)(nil)
+var _ caddy.Provisioner = (*App)(nil)
+var _ caddy.App = (*App)(nil)
 
 func (App) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
@@ -31,3 +41,63 @@ func (App) CaddyModule() caddy.ModuleInfo {
 		},
 	}
 }
+
+func (app *App) Provision(ctx caddy.Context) error {
+	module, err := ctx.LoadModuleByID(
+		"http",
+		caddyconfig.JSON(
+			caddyhttp.App{
+				Servers: map[string]*caddyhttp.Server{
+					"dns01proxy": {
+						Listen:            app.Listen,
+						Routes:            app.makeRoutes(),
+						TrustedProxiesRaw: app.TrustedProxiesRaw,
+
+						// Turns on logging.
+						Logs: &caddyhttp.ServerLogConfig{},
+					},
+				},
+			},
+			nil,
+		),
+	)
+	if err != nil {
+		return fmt.Errorf("unable to load http guest module: %w", err)
+	}
+
+	app.httpApp = module.(*caddyhttp.App)
+	return nil
+}
+
+func (app *App) Start() error {
+	return app.httpApp.Start()
+}
+
+func (app *App) Stop() error {
+	return app.httpApp.Stop()
+}
+
+func (app *App) makeRoutes() caddyhttp.RouteList {
+	return caddyhttp.RouteList{
+		{
+			HandlersRaw: []json.RawMessage{
+				caddyconfig.JSONModuleObject(
+					app.Handler,
+					"handler",
+					"dns01proxy",
+					nil,
+				),
+				caddyconfig.JSONModuleObject(
+					caddyhttp.StaticResponse{
+						StatusCode: caddyhttp.WeakString(strconv.Itoa(
+							http.StatusNotFound,
+						)),
+					},
+					"handler",
+					"static_response",
+					nil,
+				),
+			},
+		},
+	}
+}

caddy_config.go

@@ -1,15 +1,17 @@
 package caddydns01proxy
 
 import (
-	"fmt"
-
 	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/caddyconfig"
 	"github.com/liujed/caddy-dns01proxy/jsonutil"
+	"github.com/liujed/goutil/ptr"
 )
 
 // A dns01proxy configuration file is the same as the app configuration.
 type ConfigFile = App
 
+const defaultListen = "127.0.0.1:9095"
+
 // Reads a dns01proxy configuration file and returns a corresponding Caddy
 // configuration.
 func caddyConfigFromConfigFile(path string) (*caddy.Config, error) {
@@ -18,8 +20,20 @@ func caddyConfigFromConfigFile(path string) (*caddy.Config, error) {
 		return nil, err
 	}
 
-	// TODO: generate a Caddy configuration.
-	_ = config
+	// Set default listen sockets.
+	if len(config.Listen) == 0 {
+		config.Listen = []string{defaultListen}
+	}
 
-	return nil, fmt.Errorf("implement me")
+	return &caddy.Config{
+		Admin: &caddy.AdminConfig{
+			Disabled: true,
+			Config: &caddy.ConfigSettings{
+				Persist: ptr.Of(false),
+			},
+		},
+		AppsRaw: caddy.ModuleMap{
+			"dns01proxy": caddyconfig.JSON(config, nil),
+		},
+	}, nil
 }

command.go

@@ -8,6 +8,7 @@ import (
 	"github.com/liujed/caddy-dns01proxy/flags"
 	"github.com/liujed/goutil/optionals"
 	"github.com/spf13/cobra"
+	"go.uber.org/zap"
 )
 
 // Flag definitions.
@@ -71,6 +72,19 @@ func cmdRun(fs caddycmd.Flags) (int, error) {
 		return caddy.ExitCodeFailedStartup, err
 	}
 
+	// Turn on debug logs if requested.
+	if fs.Bool(flgDebug.Name) {
+		cfg.Logging = &caddy.Logging{
+			Logs: map[string]*caddy.CustomLog{
+				"default": {
+					BaseLog: caddy.BaseLog{
+						Level: zap.DebugLevel.CapitalString(),
+					},
+				},
+			},
+		}
+	}
+
 	caddy.Log().Info(fmt.Sprintf("Starting %s", Release()))
 
 	err = caddy.Run(cfg)

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/smallstep/certificates v0.26.1
 	github.com/spf13/cobra v1.9.1
 	github.com/spf13/pflag v1.0.6
+	go.uber.org/zap v1.27.0
 )
 
 require (
@@ -99,7 +100,6 @@ require (
 	go.uber.org/automaxprocs v1.6.0 // indirect
 	go.uber.org/mock v0.5.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	go.uber.org/zap v1.27.0 // indirect
 	go.uber.org/zap/exp v0.3.0 // indirect
 	golang.org/x/crypto v0.37.0 // indirect
 	golang.org/x/crypto/x509roots/fallback v0.0.0-20250305170421-49bf5b80c810 // indirect