diff --git a/caddy.go b/caddy.go
index 1655948f..51eab2e3 100644
--- a/caddy.go
+++ b/caddy.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"runtime/debug"
 	"strings"
 	"sync"
 	"time"
@@ -12,6 +13,28 @@ import (
 	"github.com/mholt/certmagic"
 )
 
+// Config represents a Caddy configuration.
+type Config struct {
+	Admin *AdminConfig `json:"admin,omitempty"`
+
+	StorageRaw json.RawMessage `json:"storage,omitempty"`
+	storage    certmagic.Storage
+
+	AppsRaw map[string]json.RawMessage `json:"apps,omitempty"`
+
+	// apps stores the decoded Apps values,
+	// keyed by module name.
+	apps map[string]App
+
+	cancelFunc context.CancelFunc
+}
+
+// App is a thing that Caddy runs.
+type App interface {
+	Start() error
+	Stop() error
+}
+
 // Run runs Caddy with the given config.
 func Run(newCfg *Config) error {
 	currentCfgMu.Lock()
@@ -69,7 +92,7 @@ func Run(newCfg *Config) error {
 			return err
 		}
 
-		// Load, Provision, Validate
+		// Load, Provision, Validate each app and their submodules
 		err = func() error {
 			for modName, rawMsg := range newCfg.AppsRaw {
 				val, err := ctx.LoadModule(modName, rawMsg)
@@ -112,7 +135,7 @@ func Run(newCfg *Config) error {
 	oldCfg := currentCfg
 	currentCfg = newCfg
 
-	// Stop, Cleanup
+	// Stop, Cleanup each old app
 	if oldCfg != nil {
 		for name, a := range oldCfg.apps {
 			err := a.Stop()
@@ -121,35 +144,13 @@ func Run(newCfg *Config) error {
 			}
 		}
 
-		// clean up old modules
+		// clean up all old modules
 		oldCfg.cancelFunc()
 	}
 
 	return nil
 }
 
-// App is a thing that Caddy runs.
-type App interface {
-	Start() error
-	Stop() error
-}
-
-// Config represents a Caddy configuration.
-type Config struct {
-	Admin *AdminConfig `json:"admin,omitempty"`
-
-	StorageRaw json.RawMessage `json:"storage,omitempty"`
-	storage    certmagic.Storage
-
-	AppsRaw map[string]json.RawMessage `json:"apps,omitempty"`
-
-	// apps stores the decoded Apps values,
-	// keyed by module name.
-	apps map[string]App
-
-	cancelFunc context.CancelFunc
-}
-
 // Duration is a JSON-string-unmarshable duration type.
 type Duration time.Duration
 
@@ -163,6 +164,29 @@ func (d *Duration) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+// GoModule returns the build info of this Caddy
+// build 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 GoModule() *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 == goModule {
+				return mod
+			}
+		}
+	}
+	return &debug.Module{Version: "unknown"}
+}
+
+// goModule is the name of this Go module.
+const goModule = "github.com/mholt/caddy"
+
 // CtxKey is a value type for use with context.WithValue.
 type CtxKey string
 
diff --git a/cmd/commands.go b/cmd/commands.go
index 4745af7c..3f866d10 100644
--- a/cmd/commands.go
+++ b/cmd/commands.go
@@ -10,8 +10,10 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 
 	"github.com/caddyserver/caddy"
+	"github.com/mholt/certmagic"
 	"github.com/mitchellh/go-ps"
 )
 
@@ -126,6 +128,11 @@ func cmdRun() (int, error) {
 		}
 	}
 
+	// set a fitting User-Agent for ACME requests
+	goModule := caddy.GoModule()
+	cleanModVersion := strings.TrimPrefix(goModule.Version, "v")
+	certmagic.UserAgent = "Caddy/" + cleanModVersion
+
 	// start the admin endpoint along with any initial config
 	err := caddy.StartAdmin(config)
 	if err != nil {
@@ -180,10 +187,10 @@ func cmdStop() (int, error) {
 }
 
 func cmdVersion() (int, error) {
-	goModule := getGoBuildModule()
+	goModule := caddy.GoModule()
 	if goModule.Sum != "" {
 		// a build with a known version will also have a checksum
-		fmt.Printf("%s (%s)\n", goModule.Version, goModule.Sum)
+		fmt.Printf("%s %s\n", goModule.Version, goModule.Sum)
 	} else {
 		fmt.Println(goModule.Version)
 	}
diff --git a/cmd/main.go b/cmd/main.go
index b9baf842..9cd2ae03 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -9,7 +9,6 @@ import (
 	"log"
 	"net"
 	"os"
-	"runtime/debug"
 )
 
 // Main executes the main function of the caddy command.
@@ -66,23 +65,3 @@ func handlePingbackConn(conn net.Conn, expect []byte) error {
 	}
 	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/go.mod b/go.mod
index 76585954..62e31922 100644
--- a/go.mod
+++ b/go.mod
@@ -17,6 +17,7 @@ require (
 	github.com/klauspost/compress v1.7.1-0.20190613161414-0b31f265a57b
 	github.com/klauspost/cpuid v1.2.1
 	github.com/mholt/certmagic v0.6.2-0.20190624175158-6a42ef9fe8c2
+	github.com/mitchellh/go-ps v0.0.0-20170309133038-4fdf99ab2936
 	github.com/rs/cors v1.6.0
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
 	github.com/starlight-go/starlight v0.0.0-20181207205707-b06f321544f3
diff --git a/go.sum b/go.sum
index 97cf1282..a77b794b 100644
--- a/go.sum
+++ b/go.sum
@@ -36,6 +36,8 @@ github.com/mholt/certmagic v0.6.2-0.20190624175158-6a42ef9fe8c2 h1:xKE9kZ5C8gelJ
 github.com/mholt/certmagic v0.6.2-0.20190624175158-6a42ef9fe8c2/go.mod h1:g4cOPxcjV0oFq3qwpjSA30LReKD8AoIfwAY9VvG35NY=
 github.com/miekg/dns v1.1.3 h1:1g0r1IvskvgL8rR+AcHzUA+oFmGcQlaIm4IqakufeMM=
 github.com/miekg/dns v1.1.3/go.mod h1:W1PPwlIAgtquWBMBEV9nkV9Cazfe8ScdGz/Lj7v3Nrg=
+github.com/mitchellh/go-ps v0.0.0-20170309133038-4fdf99ab2936 h1:kw1v0NlnN+GZcU8Ma8CLF2Zzgjfx95gs3/GN3vYAPpo=
+github.com/mitchellh/go-ps v0.0.0-20170309133038-4fdf99ab2936/go.mod h1:r1VsdOzOPt1ZSrGZWFoNhsAedKnEd6r9Np1+5blZCWk=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rs/cors v1.6.0 h1:G9tHG9lebljV9mfp9SNPDL36nCDxmo3zTlAf1YgvzmI=