Support dynamic reset of minio config (#13626)

If a given MinIO config is dynamic (can be changed without restart),
ensure that it can be reset also without restart.

Signed-off-by: Shireesh Anjal <shireesh@minio.io>

cmd/admin-handlers-config-kv.go

@@ -19,6 +19,7 @@ package cmd
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"io"
 	"net/http"
@@ -78,6 +79,22 @@ func (a adminAPIHandlers) DelConfigKVHandler(w http.ResponseWriter, r *http.Requ
 		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
 		return
 	}
+
+	dynamic := config.SubSystemsDynamic.Contains(string(kvBytes))
+	if dynamic {
+		applyDynamic(ctx, objectAPI, cfg, r, w)
+	}
+}
+
+func applyDynamic(ctx context.Context, objectAPI ObjectLayer, cfg config.Config, r *http.Request, w http.ResponseWriter) {
+	// Apply dynamic values.
+	if err := applyDynamicConfig(GlobalContext, objectAPI, cfg); err != nil {
+		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
+		return
+	}
+	globalNotificationSys.SignalService(serviceReloadDynamic)
+	// Tell the client that dynamic config was applied.
+	w.Header().Set(madmin.ConfigAppliedHeader, madmin.ConfigAppliedTrue)
 }
 
 // SetConfigKVHandler - PUT /minio/admin/v3/set-config-kv
@@ -135,14 +152,7 @@ func (a adminAPIHandlers) SetConfigKVHandler(w http.ResponseWriter, r *http.Requ
 	}
 
 	if dynamic {
-		// Apply dynamic values.
-		if err := applyDynamicConfig(GlobalContext, objectAPI, cfg); err != nil {
-			writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
-			return
-		}
-		globalNotificationSys.SignalService(serviceReloadDynamic)
-		// If all values were dynamic, tell the client.
-		w.Header().Set(madmin.ConfigAppliedHeader, madmin.ConfigAppliedTrue)
+		applyDynamic(ctx, objectAPI, cfg, r, w)
 	}
 	writeSuccessResponseHeadersOnly(w)
 }

internal/config/config.go

@@ -217,6 +217,20 @@ func (kvs KVS) Empty() bool {
 	return len(kvs) == 0
 }
 
+// Clone - returns a copy of the KVS
+func (kvs KVS) Clone() KVS {
+	return append(make(KVS, 0, len(kvs)), kvs...)
+}
+
+// GetWithDefault - returns default value if key not set
+func (kvs KVS) GetWithDefault(key string, defaultKVS KVS) string {
+	v := kvs.Get(key)
+	if len(v) == 0 {
+		return defaultKVS.Get(key)
+	}
+	return v
+}
+
 // Keys returns the list of keys for the current KVS
 func (kvs KVS) Keys() []string {
 	var keys = make([]string, len(kvs))
@@ -759,10 +773,12 @@ func (c Config) SetKVS(s string, defaultKVS map[string]KVS) (dynamic bool, err e
 		kvs.Set(Enable, EnableOn)
 	}
 
-	currKVS, ok := c[subSys][tgt]
+	var currKVS KVS
+	ck, ok := c[subSys][tgt]
 	if !ok {
-		currKVS = defaultKVS[subSys]
+		currKVS = defaultKVS[subSys].Clone()
 	} else {
+		currKVS = ck.Clone()
 		for _, kv := range defaultKVS[subSys] {
 			if _, ok = currKVS.Lookup(kv.Key); !ok {
 				currKVS.Set(kv.Key, kv.Value)

internal/config/heal/heal.go

@@ -150,15 +150,15 @@ func LookupConfig(kvs config.KVS) (cfg Config, err error) {
 	if err = config.CheckValidKeys(config.HealSubSys, kvs, DefaultKVS); err != nil {
 		return cfg, err
 	}
-	cfg.Bitrot, err = config.ParseBool(env.Get(EnvBitrot, kvs.Get(Bitrot)))
+	cfg.Bitrot, err = config.ParseBool(env.Get(EnvBitrot, kvs.GetWithDefault(Bitrot, DefaultKVS)))
 	if err != nil {
 		return cfg, fmt.Errorf("'heal:bitrotscan' value invalid: %w", err)
 	}
-	cfg.Sleep, err = time.ParseDuration(env.Get(EnvSleep, kvs.Get(Sleep)))
+	cfg.Sleep, err = time.ParseDuration(env.Get(EnvSleep, kvs.GetWithDefault(Sleep, DefaultKVS)))
 	if err != nil {
 		return cfg, fmt.Errorf("'heal:max_sleep' value invalid: %w", err)
 	}
-	cfg.IOCount, err = strconv.Atoi(env.Get(EnvIOCount, kvs.Get(IOCount)))
+	cfg.IOCount, err = strconv.Atoi(env.Get(EnvIOCount, kvs.GetWithDefault(IOCount, DefaultKVS)))
 	if err != nil {
 		return cfg, fmt.Errorf("'heal:max_io' value invalid: %w", err)
 	}

internal/config/scanner/scanner.go

@@ -95,7 +95,7 @@ func LookupConfig(kvs config.KVS) (cfg Config, err error) {
 	}
 	delay := env.Get(EnvDelayLegacy, "")
 	if delay == "" {
-		delay = env.Get(EnvDelay, kvs.Get(Delay))
+		delay = env.Get(EnvDelay, kvs.GetWithDefault(Delay, DefaultKVS))
 	}
 	cfg.Delay, err = strconv.ParseFloat(delay, 64)
 	if err != nil {
@@ -103,14 +103,14 @@ func LookupConfig(kvs config.KVS) (cfg Config, err error) {
 	}
 	maxWait := env.Get(EnvMaxWaitLegacy, "")
 	if maxWait == "" {
-		maxWait = env.Get(EnvMaxWait, kvs.Get(MaxWait))
+		maxWait = env.Get(EnvMaxWait, kvs.GetWithDefault(MaxWait, DefaultKVS))
 	}
 	cfg.MaxWait, err = time.ParseDuration(maxWait)
 	if err != nil {
 		return cfg, err
 	}
 
-	cfg.Cycle, err = time.ParseDuration(env.Get(EnvCycle, kvs.Get(Cycle)))
+	cfg.Cycle, err = time.ParseDuration(env.Get(EnvCycle, kvs.GetWithDefault(Cycle, DefaultKVS)))
 	if err != nil {
 		return cfg, err
 	}