From a4bdf249dbfb0f35e0a35dad6a38db371b126800 Mon Sep 17 00:00:00 2001
From: Matthew Holt <mholt@users.noreply.github.com>
Date: Fri, 28 Jun 2019 15:39:41 -0600
Subject: Caddy 2 gets a CLI! And admin endpoint is now configurable via JSON

---
 admin.go            |  51 ++++++++++++-
 caddy.go            |   2 +
 cmd/caddy/main.go   |   1 -
 cmd/commands.go     | 205 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 cmd/main.go         |  88 ++++++++++++++++++++++
 cmd/proc_posix.go   |  16 ++++
 cmd/proc_windows.go |  15 ++++
 cmd/run.go          |  26 -------
 8 files changed, 374 insertions(+), 30 deletions(-)
 create mode 100644 cmd/commands.go
 create mode 100644 cmd/main.go
 create mode 100644 cmd/proc_posix.go
 create mode 100644 cmd/proc_windows.go
 delete mode 100644 cmd/run.go

diff --git a/admin.go b/admin.go
index cacdfd0..3ed9bf4 100644
--- a/admin.go
+++ b/admin.go
@@ -22,12 +22,47 @@ var (
 	cfgEndptSrvMu sync.Mutex
 )
 
-// StartAdmin starts Caddy's administration endpoint.
-func StartAdmin(addr string) error {
+// AdminConfig configures the admin endpoint.
+type AdminConfig struct {
+	Listen string `json:"listen,omitempty"`
+}
+
+// DefaultAdminConfig is the default configuration
+// for the administration endpoint.
+var DefaultAdminConfig = &AdminConfig{
+	Listen: "localhost:2019",
+}
+
+// StartAdmin starts Caddy's administration endpoint,
+// bootstrapping it with an optional configuration
+// in the format of JSON bytes. It opens a listener
+// resource. When no longer needed, StopAdmin should
+// be called.
+func StartAdmin(initialConfigJSON []byte) error {
 	cfgEndptSrvMu.Lock()
 	defer cfgEndptSrvMu.Unlock()
 
-	ln, err := net.Listen("tcp", addr)
+	adminConfig := DefaultAdminConfig
+	if len(initialConfigJSON) > 0 {
+		var config *Config
+		err := json.Unmarshal(initialConfigJSON, &config)
+		if err != nil {
+			return fmt.Errorf("unmarshaling bootstrap config: %v", err)
+		}
+		if config != nil && config.Admin != nil {
+			adminConfig = config.Admin
+		}
+		if cfgEndptSrv != nil {
+			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+			defer cancel()
+			err := cfgEndptSrv.Shutdown(ctx)
+			if err != nil {
+				return fmt.Errorf("shutting down old admin endpoint: %v", err)
+			}
+		}
+	}
+
+	ln, err := net.Listen("tcp", adminConfig.Listen)
 	if err != nil {
 		return err
 	}
@@ -60,6 +95,16 @@ func StartAdmin(addr string) error {
 
 	go cfgEndptSrv.Serve(ln)
 
+	log.Println("Caddy 2 admin endpoint listening on", adminConfig.Listen)
+
+	if len(initialConfigJSON) > 0 {
+		err := Load(bytes.NewReader(initialConfigJSON))
+		if err != nil {
+			return fmt.Errorf("loading initial config: %v", err)
+		}
+		log.Println("Caddy 2 serving initial configuration")
+	}
+
 	return nil
 }
 
diff --git a/caddy.go b/caddy.go
index f8f6e45..1655948 100644
--- a/caddy.go
+++ b/caddy.go
@@ -136,6 +136,8 @@ type App interface {
 
 // Config represents a Caddy configuration.
 type Config struct {
+	Admin *AdminConfig `json:"admin,omitempty"`
+
 	StorageRaw json.RawMessage `json:"storage,omitempty"`
 	storage    certmagic.Storage
 
diff --git a/cmd/caddy/main.go b/cmd/caddy/main.go
index 463b1b9..bbb4956 100644
--- a/cmd/caddy/main.go
+++ b/cmd/caddy/main.go
@@ -5,7 +5,6 @@ import (
 
 	// this is where modules get plugged in
 	_ "github.com/caddyserver/caddy/modules/caddyhttp"
-	_ "github.com/caddyserver/caddy/modules/caddyhttp/caddylog"
 	_ "github.com/caddyserver/caddy/modules/caddyhttp/encode"
 	_ "github.com/caddyserver/caddy/modules/caddyhttp/encode/brotli"
 	_ "github.com/caddyserver/caddy/modules/caddyhttp/encode/gzip"
diff --git a/cmd/commands.go b/cmd/commands.go
new file mode 100644
index 0000000..4745af7
--- /dev/null
+++ b/cmd/commands.go
@@ -0,0 +1,205 @@
+package caddycmd
+
+import (
+	"crypto/rand"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/caddyserver/caddy"
+	"github.com/mitchellh/go-ps"
+)
+
+func cmdStart() (int, error) {
+	startCmd := flag.NewFlagSet("start", flag.ExitOnError)
+	startCmdConfigFlag := startCmd.String("config", "", "Configuration file")
+	startCmd.Parse(os.Args[2:])
+
+	// open a listener to which the child process will connect when
+	// it is ready to confirm that it has successfully started
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return 1, fmt.Errorf("opening listener for success confirmation: %v", err)
+	}
+	defer ln.Close()
+
+	// craft the command with a pingback address and with a
+	// pipe for its stdin, so we can tell it our confirmation
+	// code that we expect so that some random port scan at
+	// the most unfortunate time won't fool us into thinking
+	// the child succeeded (i.e. the alternative is to just
+	// wait for any connection on our listener, but better to
+	// ensure it's the process we're expecting - we can be
+	// sure by giving it some random bytes and having it echo
+	// them back to us)
+	cmd := exec.Command(os.Args[0], "run", "--pingback", ln.Addr().String())
+	if *startCmdConfigFlag != "" {
+		cmd.Args = append(cmd.Args, "--config", *startCmdConfigFlag)
+	}
+	stdinpipe, err := cmd.StdinPipe()
+	if err != nil {
+		return 1, fmt.Errorf("creating stdin pipe: %v", err)
+	}
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	// generate the random bytes we'll send to the child process
+	expect := make([]byte, 32)
+	_, err = rand.Read(expect)
+	if err != nil {
+		return 1, fmt.Errorf("generating random confirmation bytes: %v", err)
+	}
+
+	// begin writing the confirmation bytes to the child's
+	// stdin; use a goroutine since the child hasn't been
+	// started yet, and writing sychronously would result
+	// in a deadlock
+	go func() {
+		stdinpipe.Write(expect)
+		stdinpipe.Close()
+	}()
+
+	// start the process
+	err = cmd.Start()
+	if err != nil {
+		return 1, fmt.Errorf("starting caddy process: %v", err)
+	}
+
+	// there are two ways we know we're done: either
+	// the process will connect to our listener, or
+	// it will exit with an error
+	success, exit := make(chan struct{}), make(chan error)
+
+	// in one goroutine, we await the success of the child process
+	go func() {
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				log.Println(err)
+				break
+			}
+			err = handlePingbackConn(conn, expect)
+			if err == nil {
+				close(success)
+				break
+			}
+			log.Println(err)
+		}
+	}()
+
+	// in another goroutine, we await the failure of the child process
+	go func() {
+		err = cmd.Wait() // don't send on this line! Wait blocks, but send starts before it unblocks
+		exit <- err      // sending on separate line ensures select won't trigger until after Wait unblocks
+	}()
+
+	// when one of the goroutines unblocks, we're done and can exit
+	select {
+	case <-success:
+		fmt.Println("Successfully started Caddy")
+	case err := <-exit:
+		return 1, fmt.Errorf("caddy process exited with error: %v", err)
+	}
+
+	return 0, nil
+}
+
+func cmdRun() (int, error) {
+	runCmd := flag.NewFlagSet("run", flag.ExitOnError)
+	runCmdConfigFlag := runCmd.String("config", "", "Configuration file")
+	runCmdPingbackFlag := runCmd.String("pingback", "", "Echo confirmation bytes to this address on success")
+	runCmd.Parse(os.Args[2:])
+
+	// if a config file was specified for bootstrapping
+	// the server instance, load it now
+	var config []byte
+	if *runCmdConfigFlag != "" {
+		var err error
+		config, err = ioutil.ReadFile(*runCmdConfigFlag)
+		if err != nil {
+			return 1, fmt.Errorf("reading config file: %v", err)
+		}
+	}
+
+	// start the admin endpoint along with any initial config
+	err := caddy.StartAdmin(config)
+	if err != nil {
+		return 0, fmt.Errorf("starting caddy administration endpoint: %v", err)
+	}
+	defer caddy.StopAdmin()
+
+	// if we are to report to another process the successful start
+	// of the server, do so now by echoing back contents of stdin
+	if *runCmdPingbackFlag != "" {
+		confirmationBytes, err := ioutil.ReadAll(os.Stdin)
+		if err != nil {
+			return 1, fmt.Errorf("reading confirmation bytes from stdin: %v", err)
+		}
+		conn, err := net.Dial("tcp", *runCmdPingbackFlag)
+		if err != nil {
+			return 1, fmt.Errorf("dialing confirmation address: %v", err)
+		}
+		defer conn.Close()
+		_, err = conn.Write(confirmationBytes)
+		if err != nil {
+			return 1, fmt.Errorf("writing confirmation bytes to %s: %v", *runCmdPingbackFlag, err)
+		}
+	}
+
+	select {}
+}
+
+func cmdStop() (int, error) {
+	processList, err := ps.Processes()
+	if err != nil {
+		return 1, fmt.Errorf("listing processes: %v", err)
+	}
+	thisProcName := filepath.Base(os.Args[0])
+	var found bool
+	for _, p := range processList {
+		// the process we're looking for should have the same name but different PID
+		if p.Executable() == thisProcName && p.Pid() != os.Getpid() {
+			found = true
+			fmt.Printf("pid=%d\n", p.Pid())
+			fmt.Printf("Graceful stop...")
+			if err := gracefullyStopProcess(p.Pid()); err != nil {
+				return 1, err
+			}
+		}
+	}
+	if !found {
+		return 1, fmt.Errorf("Caddy is not running")
+	}
+	fmt.Println(" success")
+	return 0, nil
+}
+
+func cmdVersion() (int, error) {
+	goModule := getGoBuildModule()
+	if goModule.Sum != "" {
+		// a build with a known version will also have a checksum
+		fmt.Printf("%s (%s)\n", goModule.Version, goModule.Sum)
+	} else {
+		fmt.Println(goModule.Version)
+	}
+	return 0, nil
+}
+
+func cmdListModules() (int, error) {
+	for _, m := range caddy.Modules() {
+		fmt.Println(m)
+	}
+	return 0, nil
+}
+
+func cmdEnviron() (int, error) {
+	for _, v := range os.Environ() {
+		fmt.Println(v)
+	}
+	return 0, nil
+}
diff --git a/cmd/main.go b/cmd/main.go
new file mode 100644
index 0000000..b9baf84
--- /dev/null
+++ b/cmd/main.go
@@ -0,0 +1,88 @@
+package caddycmd
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"runtime/debug"
+)
+
+// Main executes the main function of the caddy command.
+func Main() {
+	if len(os.Args) <= 1 {
+		fmt.Println(usageString())
+		return
+	}
+
+	subcommand, ok := commands[os.Args[1]]
+	if !ok {
+		fmt.Printf("%q is not a valid command\n", os.Args[1])
+		os.Exit(2)
+	}
+
+	if exitCode, err := subcommand(); err != nil {
+		log.Println(err)
+		os.Exit(exitCode)
+	}
+}
+
+// commandFunc is a function that executes
+// a subcommand. It returns an exit code and
+// any associated error.
+type commandFunc func() (int, error)
+
+var commands = map[string]commandFunc{
+	"start":        cmdStart,
+	"stop":         cmdStop,
+	"run":          cmdRun,
+	"version":      cmdVersion,
+	"list-modules": cmdListModules,
+	"environ":      cmdEnviron,
+}
+
+func usageString() string {
+	buf := new(bytes.Buffer)
+	buf.WriteString("usage: caddy <command> [<args>]")
+	flag.CommandLine.SetOutput(buf)
+	flag.CommandLine.PrintDefaults()
+	return buf.String()
+}
+
+// handlePingbackConn reads from conn and ensures it matches
+// the bytes in expect, or returns an error if it doesn't.
+func handlePingbackConn(conn net.Conn, expect []byte) error {
+	defer conn.Close()
+	confirmationBytes, err := ioutil.ReadAll(io.LimitReader(conn, 32))
+	if err != nil {
+		return err
+	}
+	if !bytes.Equal(confirmationBytes, expect) {
+		return fmt.Errorf("wrong confirmation: %x", confirmationBytes)
+	}
+	return nil
+}
+
+// getGoBuildModule returns the build info of Caddy
+// from debug.BuildInfo (requires Go modules). If
+// no version information is available, a non-nil
+// value will still be returned, but with an
+// unknown version.
+func getGoBuildModule() *debug.Module {
+	bi, ok := debug.ReadBuildInfo()
+	if ok {
+		// The recommended way to build Caddy involves
+		// creating a separate main module, which
+		// TODO: track related Go issue: https://github.com/golang/go/issues/29228
+		for _, mod := range bi.Deps {
+			if mod.Path == "github.com/mholt/caddy" {
+				return mod
+			}
+		}
+	}
+	return &debug.Module{Version: "unknown"}
+}
diff --git a/cmd/proc_posix.go b/cmd/proc_posix.go
new file mode 100644
index 0000000..6b71d1a
--- /dev/null
+++ b/cmd/proc_posix.go
@@ -0,0 +1,16 @@
+// +build !windows
+
+package caddycmd
+
+import (
+	"fmt"
+	"syscall"
+)
+
+func gracefullyStopProcess(pid int) error {
+	err := syscall.Kill(pid, syscall.SIGINT)
+	if err != nil {
+		return fmt.Errorf("kill: %v", err)
+	}
+	return nil
+}
diff --git a/cmd/proc_windows.go b/cmd/proc_windows.go
new file mode 100644
index 0000000..8b1bf23
--- /dev/null
+++ b/cmd/proc_windows.go
@@ -0,0 +1,15 @@
+package caddycmd
+
+import (
+	"fmt"
+	"os/exec"
+	"strconv"
+)
+
+func gracefullyStopProcess(pid int) error {
+	cmd := exec.Command("taskkill", "/pid", strconv.Itoa(pid))
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("taskkill: %v", err)
+	}
+	return nil
+}
diff --git a/cmd/run.go b/cmd/run.go
deleted file mode 100644
index 703e119..0000000
--- a/cmd/run.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package caddycmd
-
-import (
-	"flag"
-	"log"
-
-	"github.com/caddyserver/caddy"
-)
-
-// Main executes the main function of the caddy command.
-func Main() {
-	flag.Parse()
-
-	err := caddy.StartAdmin(*listenAddr)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer caddy.StopAdmin()
-
-	log.Println("Caddy 2 admin endpoint listening on", *listenAddr)
-
-	select {}
-}
-
-// TODO: for dev only
-var listenAddr = flag.String("listen", ":1234", "The admin endpoint listener address")
-- 
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