Add crawler delay config + dynamic config values (#11018)

pkg/env/env.go

@@ -24,10 +24,19 @@ import (
 
 var (
 	privateMutex sync.RWMutex
+	lockEnvMutex sync.Mutex
 	envOff       bool
 )
 
+// LockSetEnv locks modifications to environment.
+// Call returned function to unlock.
+func LockSetEnv() func() {
+	lockEnvMutex.Lock()
+	return lockEnvMutex.Unlock
+}
+
 // SetEnvOff - turns off env lookup
+// A global lock above this MUST ensure that
 func SetEnvOff() {
 	privateMutex.Lock()
 	defer privateMutex.Unlock()

pkg/madmin/config-kv-commands.go

@@ -50,11 +50,19 @@ func (adm *AdminClient) DelConfigKV(ctx context.Context, k string) (err error) {
 	return nil
 }
 
+const (
+	// ConfigAppliedHeader is the header indicating whether the config was applied without requiring a restart.
+	ConfigAppliedHeader = "x-minio-config-applied"
+
+	// ConfigAppliedTrue is the value set in header if the config was applied.
+	ConfigAppliedTrue = "true"
+)
+
 // SetConfigKV - set key value config to server.
-func (adm *AdminClient) SetConfigKV(ctx context.Context, kv string) (err error) {
+func (adm *AdminClient) SetConfigKV(ctx context.Context, kv string) (restart bool, err error) {
 	econfigBytes, err := EncryptData(adm.getSecretKey(), []byte(kv))
 	if err != nil {
-		return err
+		return false, err
 	}
 
 	reqData := requestData{
@@ -67,14 +75,14 @@ func (adm *AdminClient) SetConfigKV(ctx context.Context, kv string) (err error)
 
 	defer closeResponse(resp)
 	if err != nil {
-		return err
+		return false, err
 	}
 
 	if resp.StatusCode != http.StatusOK {
-		return httpRespToErrorResponse(resp)
+		return false, httpRespToErrorResponse(resp)
 	}
 
-	return nil
+	return resp.Header.Get(ConfigAppliedHeader) != ConfigAppliedTrue, nil
 }
 
 // GetConfigKV - returns the key, value of the requested key, incoming data is encrypted.