Deprecate --v2-deprecation and schedule to remove it in 3.8

server/config/v2_deprecation.go

@@ -17,47 +17,50 @@ package config
 type V2DeprecationEnum string
 
 const (
-	// No longer supported in v3.6
+	// V2Depr0NotYet means v2store isn't deprecated yet.
+	// Default in v3.5, and no longer supported in v3.6.
 	V2Depr0NotYet = V2DeprecationEnum("not-yet")
-	// No longer supported in v3.6
-	//
-	// Deprecated: Please use V2Depr0NotYet.
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2Depr0NotYet.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_0_NOT_YET = V2Depr0NotYet
-	// Default in v3.6.  Meaningful v2 state is not allowed.
-	// The V2 files are maintained for v3.5 rollback.
 
-	V2Depr1WriteOnly = V2DeprecationEnum("write-only")
+	// V2Depr1WriteOnly means only writing v2store is allowed.
 	// Default in v3.6.  Meaningful v2 state is not allowed.
 	// The V2 files are maintained for v3.5 rollback.
-	//
-	// Deprecated: Please use V2Depr1WriteOnly.
+	V2Depr1WriteOnly = V2DeprecationEnum("write-only")
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2Depr1WriteOnly.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_1_WRITE_ONLY = V2Depr1WriteOnly
 
-	// V2store is WIPED if found !!!
+	// V2Depr1WriteOnlyDrop means v2store is WIPED if found !!!
+	// Will be default in 3.7.
 	V2Depr1WriteOnlyDrop = V2DeprecationEnum("write-only-drop-data")
-	// V2store is WIPED if found !!!
-	//
-	// Deprecated: Pleae use V2Depr1WriteOnlyDrop.
+
+	// Deprecated: to be decommissioned in 3.7. Pleae use V2Depr1WriteOnlyDrop.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_1_WRITE_ONLY_DROP = V2Depr1WriteOnlyDrop
 
-	// V2store is neither written nor read. Usage of this configuration is blocking
+	// V2Depr2Gone means v2store is completely gone. The v2store is
+	// neither written nor read. Anything related to v2store will be
+	// cleaned up in v3.8. Usage of this configuration is blocking
 	// ability to rollback to etcd v3.5.
 	V2Depr2Gone = V2DeprecationEnum("gone")
-	// V2store is neither written nor read. Usage of this configuration is blocking
-	// ability to rollback to etcd v3.5.
-	//
-	// Deprecated: Please use V2Depr2Gone
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2Depr2Gone.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_2_GONE = V2Depr2Gone
 
-	// Default deprecation level.
+	// V2DeprDefault is the default deprecation level.
 	V2DeprDefault = V2Depr1WriteOnly
-	// Default deprecation level.
-	//
-	// Deprecated: Please use V2DeprDefault.
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2DeprDefault.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_DEFAULT = V2DeprDefault
 )

server/embed/config.go

@@ -459,7 +459,9 @@ type Config struct {
 	// ExperimentalStopGRPCServiceOnDefrag enables etcd gRPC service to stop serving client requests on defragmentation.
 	ExperimentalStopGRPCServiceOnDefrag bool `json:"experimental-stop-grpc-service-on-defrag"`
 
-	// V2Deprecation describes phase of API & Storage V2 support
+	// V2Deprecation describes phase of API & Storage V2 support.
+	// Deprecated and scheduled for removal in v3.8.
+	// Do not set this field for embedded use cases, as it has no effect. However, setting it will not cause any harm.
 	V2Deprecation config.V2DeprecationEnum `json:"v2-deprecation"`
 
 	// ServerFeatureGate is a server level feature gate

server/embed/etcd.go

@@ -376,6 +376,8 @@ func print(lg *zap.Logger, ec Config, sc config.ServerConfig, memberInitialized
 
 		zap.String("downgrade-check-interval", sc.DowngradeCheckTime.String()),
 		zap.Int("max-learners", sc.ExperimentalMaxLearners),
+
+		zap.String("v2-deprecation", string(ec.V2Deprecation)),
 	)
 }
 

server/etcdmain/config.go

@@ -60,6 +60,7 @@ var (
 	deprecatedFlags = map[string]string{
 		// TODO: remove in 3.7.
 		"snapshot-count": "--snapshot-count is deprecated in 3.6 and will be decommissioned in 3.7.",
+		"v2-deprecation": "--v2-deprecation is deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input.",
 	}
 )
 
@@ -74,9 +75,11 @@ type config struct {
 
 // configFlags has the set of flags used for command line parsing a Config
 type configFlags struct {
-	flagSet       *flag.FlagSet
-	clusterState  *flags.SelectiveStringValue
-	fallback      *flags.SelectiveStringValue
+	flagSet      *flag.FlagSet
+	clusterState *flags.SelectiveStringValue
+	fallback     *flags.SelectiveStringValue
+	// Deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input.
+	// TODO: remove in v3.8.
 	v2deprecation *flags.SelectiveStringsValue
 }
 
@@ -108,7 +111,7 @@ func newConfig() *config {
 	fs.StringVar(&cfg.configFile, "config-file", "", "Path to the server configuration file. Note that if a configuration file is provided, other command line flags and environment variables will be ignored.")
 	fs.Var(cfg.cf.fallback, "discovery-fallback", fmt.Sprintf("Valid values include %q", cfg.cf.fallback.Valids()))
 	fs.Var(cfg.cf.clusterState, "initial-cluster-state", "Initial cluster state ('new' when bootstrapping a new cluster or 'existing' when adding new members to an existing cluster). After successful initialization (bootstrapping or adding), flag is ignored on restarts.")
-	fs.Var(cfg.cf.v2deprecation, "v2-deprecation", fmt.Sprintf("v2store deprecation stage: %q. ", cfg.cf.v2deprecation.Valids()))
+	fs.Var(cfg.cf.v2deprecation, "v2-deprecation", fmt.Sprintf("v2store deprecation stage: %q. Deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input.", cfg.cf.v2deprecation.Valids()))
 
 	fs.BoolVar(&cfg.printVersion, "version", false, "Print the version and exit.")
 	// ignored
@@ -161,9 +164,8 @@ func (cfg *config) parse(arguments []string) error {
 		err = cfg.configFromCmdLine()
 	}
 
-	if cfg.ec.V2Deprecation == "" {
-		cfg.ec.V2Deprecation = cconfig.V2DeprDefault
-	}
+	// `V2Deprecation` (--v2-deprecation) is deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input.
+	cfg.ec.V2Deprecation = cconfig.V2DeprDefault
 
 	cfg.ec.WarningUnaryRequestDuration, perr = cfg.parseWarningUnaryRequestDuration()
 	if perr != nil {

server/etcdmain/help.go

@@ -169,12 +169,12 @@ Clustering:
   --auto-compaction-mode 'periodic'
     Interpret 'auto-compaction-retention' one of: periodic|revision. 'periodic' for duration based retention, defaulting to hours if no time unit is provided (e.g. '5m'). 'revision' for revision number based retention.
   --v2-deprecation '` + string(cconfig.V2DeprDefault) + `'
-    Phase of v2store deprecation. Allows to opt-in for higher compatibility mode.
+    Phase of v2store deprecation. Deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input.
     Supported values:
       'not-yet'                // Issues a warning if v2store have meaningful content (default in v3.5)
-      'write-only'             // Custom v2 state is not allowed (planned default in v3.6)
-      'write-only-drop-data'   // Custom v2 state will get DELETED !
-      'gone'                   // v2store is not maintained any longer. (planned default in v3.7)
+      'write-only'             // Custom v2 state is not allowed (default in v3.6)
+      'write-only-drop-data'   // Custom v2 state will get DELETED ! (planned default in v3.7)
+      'gone'                   // v2store is not maintained any longer. (planned to cleanup anything related to v2store in v3.8)
 
 Security:
   --cert-file ''

tests/e2e/etcd_config_test.go

@@ -666,17 +666,67 @@ func TestEtcdTLSVersion(t *testing.T) {
 func TestEtcdDeprecatedFlags(t *testing.T) {
 	e2e.SkipInShortMode(t)
 
-	proc, err := e2e.SpawnCmd(
-		[]string{
-			e2e.BinPath.Etcd,
-			"--name", "e1",
-			"--snapshot-count=100",
-		}, nil,
-	)
-	require.NoError(t, err)
-	require.NoError(t, e2e.WaitReadyExpectProc(context.TODO(), proc, []string{"--snapshot-count is deprecated in 3.6 and will be decommissioned in 3.7"}))
-	require.NoError(t, proc.Stop())
+	commonArgs := []string{
+		e2e.BinPath.Etcd,
+		"--name", "e1",
+	}
 
-	proc.Wait() // ensure the port has been released
-	proc.Close()
+	testCases := []struct {
+		name        string
+		args        []string
+		expectedMsg string
+	}{
+		{
+			name:        "snapshot-count",
+			args:        append(commonArgs, "--snapshot-count=100"),
+			expectedMsg: "--snapshot-count is deprecated in 3.6 and will be decommissioned in 3.7",
+		},
+		{
+			name:        "v2-deprecation",
+			args:        append(commonArgs, "--v2-deprecation", "write-only-drop-data"),
+			expectedMsg: "--v2-deprecation is deprecated and scheduled for removal in v3.8. The default value is enforced, ignoring user input",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			proc, err := e2e.SpawnCmd(
+				tc.args, nil,
+			)
+			require.NoError(t, err)
+			require.NoError(t, e2e.WaitReadyExpectProc(context.TODO(), proc, []string{tc.expectedMsg}))
+			require.NoError(t, proc.Stop())
+
+			proc.Wait() // ensure the port has been released
+			proc.Close()
+		})
+	}
+}
+
+// TestV2DeprecationEnforceDefaultValue verifies that etcd enforces the default V2Deprecation level
+// and ignores users input.
+func TestV2DeprecationEnforceDefaultValue(t *testing.T) {
+	e2e.SkipInShortMode(t)
+
+	commonArgs := []string{
+		e2e.BinPath.Etcd,
+		"--name", "e1",
+	}
+
+	validV2DeprecationLevels := []string{"write-only", "write-only-drop-data", "gone"}
+	expectedDeprecationLevelMsg := `"v2-deprecation":"write-only"`
+
+	for _, optionLevel := range validV2DeprecationLevels {
+		t.Run(optionLevel, func(t *testing.T) {
+			proc, err := e2e.SpawnCmd(
+				append(commonArgs, "--v2-deprecation", optionLevel), nil,
+			)
+			require.NoError(t, err)
+			require.NoError(t, e2e.WaitReadyExpectProc(context.TODO(), proc, []string{expectedDeprecationLevelMsg}))
+			require.NoError(t, proc.Stop())
+
+			proc.Wait() // ensure the port has been released
+			proc.Close()
+		})
+	}
 }