Config auto-save; run --resume flag; update environ output (close #2903)

Config auto-saving is on by default and can be disabled. The --environ
flag (or environ subcommand) now print more useful information from
Caddy and the runtime, including some nifty paths.

5 files changed, 94 insertions, 24 deletions

diff --git a/admin.go b/admin.go
index bf11985..7a5d0b6 100644
--- a/admin.go
+++ b/admin.go
@@ -66,6 +66,16 @@ type AdminConfig struct {
 	// will be the default value. If set but empty, no origins will
 	// be allowed.
 	Origins []string `json:"origins,omitempty"`
+
+	// Options related to configuration management.
+	Config *ConfigSettings `json:"config,omitempty"`
+}
+
+// ConfigSettings configures the, uh, configuration... and
+// management thereof.
+type ConfigSettings struct {
+	// Whether to keep a copy of the active config on disk. Default is true.
+	Persist *bool `json:"persist,omitempty"`
 }
 
 // listenAddr extracts a singular listen address from ac.Listen,
@@ -775,7 +785,11 @@ traverseLoop:
 	return nil
 }
 
-// RemoveMetaFields removes meta fields like "@id" from a JSON message.
+// RemoveMetaFields removes meta fields like "@id" from a JSON message
+// by using a simple regular expression. (An alternate way to do this
+// would be to delete them from the raw, map[string]interface{}
+// representation as they are indexed, then iterate the index we made
+// and add them back after encoding as JSON, but this is simpler.)
 func RemoveMetaFields(rawJSON []byte) []byte {
 	return idRegexp.ReplaceAllFunc(rawJSON, func(in []byte) []byte {
 		// matches with a comma on both sides (when "@id" property is
diff --git a/caddy.go b/caddy.go
index f50598e..fefe50b 100644
--- a/caddy.go
+++ b/caddy.go
@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"path"
@@ -30,6 +31,7 @@ import (
 	"time"
 
 	"github.com/mholt/certmagic"
+	"go.uber.org/zap"
 )
 
 // Config is the top (or beginning) of the Caddy configuration structure.
@@ -148,13 +150,6 @@ func changeConfig(method, path string, input []byte, forceReload bool) error {
 		}
 	}
 
-	// remove any @id fields from the JSON, which would cause
-	// loading to break since the field wouldn't be recognized
-	// (an alternate way to do this would be to delete them from
-	// rawCfg as they are indexed, then iterate the index we made
-	// and add them back after encoding as JSON)
-	newCfg = RemoveMetaFields(newCfg)
-
 	// load this new config; if it fails, we need to revert to
 	// our old representation of caddy's actual config
 	err = unsyncedDecodeAndRun(newCfg)
@@ -232,15 +227,19 @@ func indexConfigObjects(ptr interface{}, configPath string, index map[string]str
 	return nil
 }
 
-// unsyncedDecodeAndRun decodes cfgJSON and runs
-// it as the new config, replacing any other
-// current config. It does not update the raw
-// config state, as this is a lower-level function;
-// most callers will want to use Load instead.
-// A write lock on currentCfgMu is required!
+// unsyncedDecodeAndRun removes any meta fields (like @id tags)
+// from cfgJSON, decodes the result into a *Config, and runs
+// it as the new config, replacing any other current config.
+// It does NOT update the raw config state, as this is a
+// lower-level function; most callers will want to use Load
+// instead. A write lock on currentCfgMu is required!
 func unsyncedDecodeAndRun(cfgJSON []byte) error {
+	// remove any @id fields from the JSON, which would cause
+	// loading to break since the field wouldn't be recognized
+	strippedCfgJSON := RemoveMetaFields(cfgJSON)
+
 	var newCfg *Config
-	err := strictUnmarshalJSON(cfgJSON, &newCfg)
+	err := strictUnmarshalJSON(strippedCfgJSON, &newCfg)
 	if err != nil {
 		return err
 	}
@@ -258,6 +257,22 @@ func unsyncedDecodeAndRun(cfgJSON []byte) error {
 	// Stop, Cleanup each old app
 	unsyncedStop(oldCfg)
 
+	// autosave a non-nil config, if not disabled
+	if newCfg != nil &&
+		(newCfg.Admin == nil ||
+			newCfg.Admin.Config == nil ||
+			newCfg.Admin.Config.Persist == nil ||
+			*newCfg.Admin.Config.Persist) {
+		err := ioutil.WriteFile(ConfigAutosavePath, cfgJSON, 0600)
+		if err == nil {
+			Log().Info("autosaved config", zap.String("file", ConfigAutosavePath))
+		} else {
+			Log().Error("unable to autosave config",
+				zap.String("file", ConfigAutosavePath),
+				zap.Error(err))
+		}
+	}
+
 	return nil
 }
 
diff --git a/cmd/commandfuncs.go b/cmd/commandfuncs.go
index cc55df2..2d8e9d8 100644
--- a/cmd/commandfuncs.go
+++ b/cmd/commandfuncs.go
@@ -27,6 +27,7 @@ import (
 	"os"
 	"os/exec"
 	"reflect"
+	"runtime"
 	"runtime/debug"
 	"sort"
 	"strings"
@@ -141,6 +142,7 @@ func cmdStart(fl Flags) (int, error) {
 func cmdRun(fl Flags) (int, error) {
 	runCmdConfigFlag := fl.String("config")
 	runCmdConfigAdapterFlag := fl.String("adapter")
+	runCmdResumeFlag := fl.Bool("resume")
 	runCmdPrintEnvFlag := fl.Bool("environ")
 	runCmdPingbackFlag := fl.String("pingback")
 
@@ -149,14 +151,32 @@ func cmdRun(fl Flags) (int, error) {
 		printEnvironment()
 	}
 
-	// get the config in caddy's native format
-	config, err := loadConfig(runCmdConfigFlag, runCmdConfigAdapterFlag)
-	if err != nil {
-		return caddy.ExitCodeFailedStartup, err
-	}
 	// TODO: This is TEMPORARY, until the RCs
 	moveStorage()
 
+	// load the config, depending on flags
+	var config []byte
+	var err error
+	if runCmdResumeFlag {
+		config, err = ioutil.ReadFile(caddy.ConfigAutosavePath)
+		if os.IsNotExist(err) {
+			// not a bad error; just can't resume if autosave file doesn't exist
+			caddy.Log().Info("no autosave file exists", zap.String("autosave_file", caddy.ConfigAutosavePath))
+			runCmdResumeFlag = false
+		} else if err != nil {
+			return caddy.ExitCodeFailedStartup, err
+		} else {
+			caddy.Log().Info("resuming from last configuration", zap.String("autosave_file", caddy.ConfigAutosavePath))
+		}
+	}
+	// we don't use 'else' here since this value might have been changed in 'if' block; i.e. not mutually exclusive
+	if !runCmdResumeFlag {
+		config, err = loadConfig(runCmdConfigFlag, runCmdConfigAdapterFlag)
+		if err != nil {
+			return caddy.ExitCodeFailedStartup, err
+		}
+	}
+
 	// set a fitting User-Agent for ACME requests
 	goModule := caddy.GoModule()
 	cleanModVersion := strings.TrimPrefix(goModule.Version, "v")
@@ -167,9 +187,7 @@ func cmdRun(fl Flags) (int, error) {
 	if err != nil {
 		return caddy.ExitCodeFailedStartup, fmt.Errorf("loading initial config: %v", err)
 	}
-	if len(config) > 0 {
-		caddy.Log().Named("admin").Info("Caddy 2 serving initial configuration")
-	}
+	caddy.Log().Info("serving initial configuration")
 
 	// if we are to report to another process the successful start
 	// of the server, do so now by echoing back contents of stdin
diff --git a/cmd/commands.go b/cmd/commands.go
index 971d8d9..93ebeff 100644
--- a/cmd/commands.go
+++ b/cmd/commands.go
@@ -116,11 +116,15 @@ line flags.
 
 If --environ is specified, the environment as seen by the Caddy process will
 be printed before starting. This is the same as the environ command but does
-not quit after printing, and can be useful for troubleshooting.`,
+not quit after printing, and can be useful for troubleshooting.
+
+The --resume flag will override the --config flag if there is a config auto-
+save file. It is not an error if --resume is used and no autosave file exists.`,
 		Flags: func() *flag.FlagSet {
 			fs := flag.NewFlagSet("run", flag.ExitOnError)
 			fs.String("config", "", "Configuration file")
 			fs.String("adapter", "", "Name of config adapter to apply")
+			fs.Bool("resume", false, "Use saved config, if any (and prefer over --config file)")
 			fs.Bool("environ", false, "Print environment")
 			fs.String("pingback", "", "Echo confirmation bytes to this address on success")
 			return fs
diff --git a/cmd/main.go b/cmd/main.go
index ca9b914..564ef9f 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -110,6 +110,9 @@ func loadConfig(configFile, adapterName string) ([]byte, error) {
 		if err != nil {
 			return nil, fmt.Errorf("reading config file: %v", err)
 		}
+		caddy.Log().Info("using provided configuration",
+			zap.String("config_file", configFile),
+			zap.String("config_adapter", adapterName))
 	} else if adapterName == "" {
 		// as a special case when no config file or adapter
 		// is specified, see if the Caddyfile adapter is
@@ -126,6 +129,7 @@ func loadConfig(configFile, adapterName string) ([]byte, error) {
 			} else {
 				// success reading default Caddyfile
 				configFile = "Caddyfile"
+				caddy.Log().Info("using adjacent Caddyfile")
 			}
 		}
 	}
@@ -225,6 +229,21 @@ func flagHelp(fs *flag.FlagSet) string {
 }
 
 func printEnvironment() {
+	fmt.Printf("caddy.HomeDir=%s\n", caddy.HomeDir())
+	fmt.Printf("caddy.AppDataDir=%s\n", caddy.AppDataDir())
+	fmt.Printf("caddy.AppConfigDir=%s\n", caddy.AppConfigDir())
+	fmt.Printf("caddy.ConfigAutosavePath=%s\n", caddy.ConfigAutosavePath)
+	fmt.Printf("runtime.GOOS=%s\n", runtime.GOOS)
+	fmt.Printf("runtime.GOARCH=%s\n", runtime.GOARCH)
+	fmt.Printf("runtime.Compiler=%s\n", runtime.Compiler)
+	fmt.Printf("runtime.NumCPU=%d\n", runtime.NumCPU())
+	fmt.Printf("runtime.GOMAXPROCS=%d\n", runtime.GOMAXPROCS(0))
+	fmt.Printf("runtime.Version=%s\n", runtime.Version())
+	cwd, err := os.Getwd()
+	if err != nil {
+		cwd = fmt.Sprintf("<error: %v>", err)
+	}
+	fmt.Printf("os.Getwd=%s\n\n", cwd)
 	for _, v := range os.Environ() {
 		fmt.Println(v)
 	}