Handle errs returned with etcd properly for config init and migration (#7134)

Returning unexpected errors can cause problems for config handling,
which is what led gateway deployments with etcd to misbehave and
had stopped working properly

cmd/admin-handlers_test.go

@@ -278,7 +278,7 @@ func prepareAdminXLTestBed() (*adminXLTestBed, error) {
 
 	// Setup admin mgmt REST API handlers.
 	adminRouter := mux.NewRouter()
-	registerAdminRouter(adminRouter, true)
+	registerAdminRouter(adminRouter, true, true)
 
 	return &adminXLTestBed{
 		xlDirs:   xlDirs,

cmd/admin-router.go

@@ -31,7 +31,7 @@ type adminAPIHandlers struct {
 }
 
 // registerAdminRouter - Add handler functions for each service REST API routes.
-func registerAdminRouter(router *mux.Router, enableIAM bool) {
+func registerAdminRouter(router *mux.Router, enableConfigOps, enableIAMOps bool) {
 
 	adminAPI := adminAPIHandlers{}
 	// Admin router
@@ -73,8 +73,7 @@ func registerAdminRouter(router *mux.Router, enableIAM bool) {
 	adminV1Router.Methods(http.MethodGet).Path("/profiling/download").HandlerFunc(httpTraceAll(adminAPI.DownloadProfilingHandler))
 
 	/// Config operations
-
-	if enableIAM {
+	if enableConfigOps {
 		// Update credentials
 		adminV1Router.Methods(http.MethodPut).Path("/config/credential").HandlerFunc(httpTraceHdrs(adminAPI.UpdateAdminCredentialsHandler))
 		// Get config
@@ -86,11 +85,14 @@ func registerAdminRouter(router *mux.Router, enableIAM bool) {
 		adminV1Router.Methods(http.MethodGet).Path("/config-keys").HandlerFunc(httpTraceHdrs(adminAPI.GetConfigKeysHandler))
 		// Set config keys/values
 		adminV1Router.Methods(http.MethodPut).Path("/config-keys").HandlerFunc(httpTraceHdrs(adminAPI.SetConfigKeysHandler))
+	}
 
+	if enableIAMOps {
 		// -- IAM APIs --
 
 		// Add policy IAM
-		adminV1Router.Methods(http.MethodPut).Path("/add-canned-policy").HandlerFunc(httpTraceHdrs(adminAPI.AddCannedPolicy)).Queries("name", "{name:.*}")
+		adminV1Router.Methods(http.MethodPut).Path("/add-canned-policy").HandlerFunc(httpTraceHdrs(adminAPI.AddCannedPolicy)).Queries("name",
+			"{name:.*}")
 
 		// Add user IAM
 		adminV1Router.Methods(http.MethodPut).Path("/add-user").HandlerFunc(httpTraceHdrs(adminAPI.AddUser)).Queries("accessKey", "{accessKey:.*}")

cmd/config-migrate.go

@@ -27,7 +27,6 @@ import (
 	"github.com/minio/minio/cmd/crypto"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/auth"
-	"github.com/minio/minio/pkg/dns"
 	"github.com/minio/minio/pkg/event"
 	"github.com/minio/minio/pkg/event/target"
 	"github.com/minio/minio/pkg/iam/policy"
@@ -235,7 +234,7 @@ func purgeV1() error {
 
 	cv1 := &configV1{}
 	_, err := Load(configFile, cv1)
-	if os.IsNotExist(err) || err == dns.ErrNoEntriesFound {
+	if os.IsNotExist(err) {
 		return nil
 	} else if err != nil {
 		return fmt.Errorf("Unable to load config version ‘1’. %v", err)
@@ -2454,10 +2453,14 @@ func migrateConfigToMinioSys(objAPI ObjectLayer) (err error) {
 		}
 		// Read from deprecate file as well if necessary.
 		if _, err = Load(getConfigFile()+".deprecated", config); err != nil {
+			if !os.IsNotExist(err) {
 				return err
 			}
+			// If all else fails simply initialize the server config.
+			return newSrvConfig(objAPI)
 		}
 
+	}
 	return saveServerConfig(context.Background(), objAPI, config)
 }
 

cmd/config.go

@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
-	"os"
 	"path"
 	"runtime"
 	"strings"
@@ -160,16 +159,19 @@ func initConfig(objAPI ObjectLayer) error {
 
 	if globalEtcdClient != nil {
 		if err := checkConfigEtcd(context.Background(), globalEtcdClient, getConfigFile()); err != nil {
-			return err
-		}
+			if err == errConfigNotFound {
 				// Migrates all configs at old location.
-		if err := migrateConfig(); err != nil {
+				if err = migrateConfig(); err != nil {
 					return err
 				}
 				// Migrates etcd ${HOME}/.minio/config.json to '/config/config.json'
-		if err := migrateConfigToMinioSys(objAPI); err != nil {
+				if err = migrateConfigToMinioSys(objAPI); err != nil {
 					return err
 				}
+			} else {
+				return err
+			}
+		}
 	} else {
 		if isFile(getConfigFile()) {
 			if err := migrateConfig(); err != nil {
@@ -179,7 +181,7 @@ func initConfig(objAPI ObjectLayer) error {
 		// Migrates ${HOME}/.minio/config.json or config.json.deprecated
 		// to '<export_path>/.minio.sys/config/config.json'
 		// ignore if the file doesn't exist.
-		if err := migrateConfigToMinioSys(objAPI); err != nil && !os.IsNotExist(err) {
+		if err := migrateConfigToMinioSys(objAPI); err != nil {
 			return err
 		}
 	}
@@ -189,17 +191,6 @@ func initConfig(objAPI ObjectLayer) error {
 	// Watch config for changes and reloads them in-memory.
 	go watchConfig(objAPI, configFile, loadConfig)
 
-	if err := checkConfig(context.Background(), objAPI, configFile); err != nil {
-		if err == errConfigNotFound {
-			// Config file does not exist, we create it fresh and return upon success.
-			if err = newSrvConfig(objAPI); err != nil {
-				return err
-			}
-		} else {
-			return err
-		}
-	}
-
 	if err := migrateMinioSysConfig(objAPI); err != nil {
 		return err
 	}

cmd/gateway-main.go

@@ -155,9 +155,12 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 		registerSTSRouter(router)
 	}
 
+	enableConfigOps := globalEtcdClient != nil && gatewayName == "nas"
+	enableIAMOps := globalEtcdClient != nil
+
 	// Enable IAM admin APIs if etcd is enabled, if not just enable basic
 	// operations such as profiling, server info etc.
-	registerAdminRouter(router, globalEtcdClient != nil)
+	registerAdminRouter(router, enableConfigOps, enableIAMOps)
 
 	// Add healthcheck router
 	registerHealthCheckRouter(router)
@@ -215,7 +218,7 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 		logger.FatalIf(err, "Unable to initialize gateway backend")
 	}
 
-	if globalEtcdClient != nil && gatewayName == "nas" {
+	if enableConfigOps {
 		// Create a new config system.
 		globalConfigSys = NewConfigSys()
 
@@ -242,7 +245,7 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 
 	// Create new IAM system.
 	globalIAMSys = NewIAMSys()
-	if globalEtcdClient != nil {
+	if enableIAMOps {
 		// Initialize IAM sys.
 		_ = globalIAMSys.Init(newObject)
 	}

cmd/routers.go

@@ -105,7 +105,7 @@ func configureServerHandler(endpoints EndpointList) (http.Handler, error) {
 	registerSTSRouter(router)
 
 	// Add Admin router, all APIs are enabled in server mode.
-	registerAdminRouter(router, true)
+	registerAdminRouter(router, true, true)
 
 	// Add healthcheck router
 	registerHealthCheckRouter(router)

pkg/quick/encoding.go

@@ -31,7 +31,6 @@ import (
 	"time"
 
 	etcd "github.com/coreos/etcd/clientv3"
-	dns "github.com/minio/minio/pkg/dns"
 	yaml "gopkg.in/yaml.v2"
 )
 
@@ -160,7 +159,7 @@ func loadFileConfigEtcd(filename string, clnt *etcd.Client, v interface{}) error
 		return fmt.Errorf("unexpected error %s returned by etcd setup, please check your endpoints %s", err, clnt.Endpoints())
 	}
 	if resp.Count == 0 {
-		return dns.ErrNoEntriesFound
+		return os.ErrNotExist
 	}
 
 	for _, ev := range resp.Kvs {
@@ -173,7 +172,7 @@ func loadFileConfigEtcd(filename string, clnt *etcd.Client, v interface{}) error
 			return toUnmarshaller(filepath.Ext(filename))(fileData, v)
 		}
 	}
-	return dns.ErrNoEntriesFound
+	return os.ErrNotExist
 }
 
 // loadFileConfig unmarshals the file's content with the right