agent: enable enable_central_service_config by default (#8746)

.changelog/8746.txt

@@ -0,0 +1,3 @@
+```release-note:breaking-change
+agent: The `enable_central_service_config` option now defaults to true.
+```

agent/agent_endpoint_test.go

@@ -2694,7 +2694,7 @@ func TestAgent_UpdateCheck_ACLDeny(t *testing.T) {
 func TestAgent_RegisterService(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService(t, "")
+		testAgent_RegisterService(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2780,7 +2780,7 @@ func testAgent_RegisterService(t *testing.T, extraHCL string) {
 func TestAgent_RegisterService_ReRegister(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ReRegister(t, "")
+		testAgent_RegisterService_ReRegister(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2856,7 +2856,7 @@ func testAgent_RegisterService_ReRegister(t *testing.T, extraHCL string) {
 func TestAgent_RegisterService_ReRegister_ReplaceExistingChecks(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ReRegister_ReplaceExistingChecks(t, "")
+		testAgent_RegisterService_ReRegister_ReplaceExistingChecks(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2931,7 +2931,7 @@ func testAgent_RegisterService_ReRegister_ReplaceExistingChecks(t *testing.T, ex
 func TestAgent_RegisterService_TranslateKeys(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ACLDeny(t, "")
+		testAgent_RegisterService_ACLDeny(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3147,7 +3147,7 @@ func testAgent_RegisterService_TranslateKeys(t *testing.T, extraHCL string) {
 func TestAgent_RegisterService_ACLDeny(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ACLDeny(t, "")
+		testAgent_RegisterService_ACLDeny(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3197,7 +3197,7 @@ func testAgent_RegisterService_ACLDeny(t *testing.T, extraHCL string) {
 func TestAgent_RegisterService_InvalidAddress(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_UnmanagedConnectProxy(t, "")
+		testAgent_RegisterService_InvalidAddress(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3241,7 +3241,7 @@ func testAgent_RegisterService_InvalidAddress(t *testing.T, extraHCL string) {
 func TestAgent_RegisterService_UnmanagedConnectProxy(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_UnmanagedConnectProxy(t, "")
+		testAgent_RegisterService_UnmanagedConnectProxy(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3375,7 +3375,7 @@ func testCreatePolicy(t *testing.T, a *TestAgent, name, rules string) string {
 func TestAgent_RegisterServiceDeregisterService_Sidecar(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterServiceDeregisterService_Sidecar(t, "")
+		testAgent_RegisterServiceDeregisterService_Sidecar(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3871,7 +3871,7 @@ func testAgent_RegisterServiceDeregisterService_Sidecar(t *testing.T, extraHCL s
 func TestAgent_RegisterService_UnmanagedConnectProxyInvalid(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_UnmanagedConnectProxyInvalid(t, "")
+		testAgent_RegisterService_UnmanagedConnectProxyInvalid(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3914,7 +3914,7 @@ func testAgent_RegisterService_UnmanagedConnectProxyInvalid(t *testing.T, extraH
 func TestAgent_RegisterService_ConnectNative(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ConnectNative(t, "")
+		testAgent_RegisterService_ConnectNative(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3959,7 +3959,7 @@ func testAgent_RegisterService_ConnectNative(t *testing.T, extraHCL string) {
 func TestAgent_RegisterService_ScriptCheck_ExecDisable(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ScriptCheck_ExecDisable(t, "")
+		testAgent_RegisterService_ScriptCheck_ExecDisable(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -4005,7 +4005,7 @@ func testAgent_RegisterService_ScriptCheck_ExecDisable(t *testing.T, extraHCL st
 func TestAgent_RegisterService_ScriptCheck_ExecRemoteDisable(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RegisterService_ScriptCheck_ExecRemoteDisable(t, "")
+		testAgent_RegisterService_ScriptCheck_ExecRemoteDisable(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()

agent/agent_test.go

@@ -255,7 +255,7 @@ func TestAgent_ReconnectConfigWanDisabled(t *testing.T) {
 func TestAgent_AddService(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_AddService(t, "")
+		testAgent_AddService(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -451,7 +451,7 @@ func testAgent_AddService(t *testing.T, extraHCL string) {
 func TestAgent_AddServices_AliasUpdateCheckNotReverted(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_AddServices_AliasUpdateCheckNotReverted(t, "")
+		testAgent_AddServices_AliasUpdateCheckNotReverted(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -669,7 +669,7 @@ func TestAgent_CheckAliasRPC(t *testing.T) {
 func TestAgent_AddServiceNoExec(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_AddServiceNoExec(t, "")
+		testAgent_AddServiceNoExec(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -711,7 +711,7 @@ func testAgent_AddServiceNoExec(t *testing.T, extraHCL string) {
 func TestAgent_AddServiceNoRemoteExec(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_AddServiceNoRemoteExec(t, "")
+		testAgent_AddServiceNoRemoteExec(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -977,7 +977,7 @@ func TestAddServiceIPv6TaggedSet(t *testing.T) {
 func TestAgent_RemoveService(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RemoveService(t, "")
+		testAgent_RemoveService(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -1088,7 +1088,7 @@ func testAgent_RemoveService(t *testing.T, extraHCL string) {
 func TestAgent_RemoveServiceRemovesAllChecks(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_RemoveServiceRemovesAllChecks(t, "")
+		testAgent_RemoveServiceRemovesAllChecks(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2009,7 +2009,7 @@ func TestAgent_updateTTLCheck(t *testing.T) {
 func TestAgent_PersistService(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_PersistService(t, "")
+		testAgent_PersistService(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2108,7 +2108,7 @@ func testAgent_PersistService(t *testing.T, extraHCL string) {
 func TestAgent_persistedService_compat(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_persistedService_compat(t, "")
+		testAgent_persistedService_compat(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2162,7 +2162,7 @@ func testAgent_persistedService_compat(t *testing.T, extraHCL string) {
 func TestAgent_PurgeService(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_PurgeService(t, "")
+		testAgent_PurgeService(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2217,7 +2217,7 @@ func testAgent_PurgeService(t *testing.T, extraHCL string) {
 func TestAgent_PurgeServiceOnDuplicate(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_PurgeServiceOnDuplicate(t, "")
+		testAgent_PurgeServiceOnDuplicate(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2501,7 +2501,7 @@ func TestAgent_unloadChecks(t *testing.T) {
 func TestAgent_loadServices_token(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_loadServices_token(t, "")
+		testAgent_loadServices_token(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2531,7 +2531,7 @@ func testAgent_loadServices_token(t *testing.T, extraHCL string) {
 func TestAgent_loadServices_sidecar(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_loadServices_sidecar(t, "")
+		testAgent_loadServices_sidecar(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2572,7 +2572,7 @@ func testAgent_loadServices_sidecar(t *testing.T, extraHCL string) {
 func TestAgent_loadServices_sidecarSeparateToken(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_loadServices_sidecarSeparateToken(t, "")
+		testAgent_loadServices_sidecarSeparateToken(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2611,7 +2611,7 @@ func testAgent_loadServices_sidecarSeparateToken(t *testing.T, extraHCL string)
 func TestAgent_loadServices_sidecarInheritMeta(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_loadServices_sidecarInheritMeta(t, "")
+		testAgent_loadServices_sidecarInheritMeta(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2655,7 +2655,7 @@ func testAgent_loadServices_sidecarInheritMeta(t *testing.T, extraHCL string) {
 func TestAgent_loadServices_sidecarOverrideMeta(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_loadServices_sidecarOverrideMeta(t, "")
+		testAgent_loadServices_sidecarOverrideMeta(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2703,7 +2703,7 @@ func testAgent_loadServices_sidecarOverrideMeta(t *testing.T, extraHCL string) {
 func TestAgent_unloadServices(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_unloadServices(t, "")
+		testAgent_unloadServices(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -2905,7 +2905,7 @@ func TestAgent_Service_NoReap(t *testing.T) {
 func TestAgent_AddService_restoresSnapshot(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_AddService_restoresSnapshot(t, "")
+		testAgent_AddService_restoresSnapshot(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()
@@ -3399,7 +3399,7 @@ func TestAgent_ReloadConfigOutgoingRPCConfig(t *testing.T) {
 func TestAgent_ReloadConfigAndKeepChecksStatus(t *testing.T) {
 	t.Run("normal", func(t *testing.T) {
 		t.Parallel()
-		testAgent_ReloadConfigAndKeepChecksStatus(t, "")
+		testAgent_ReloadConfigAndKeepChecksStatus(t, "enable_central_service_config = false")
 	})
 	t.Run("service manager", func(t *testing.T) {
 		t.Parallel()

agent/config/default.go

@@ -45,6 +45,7 @@ func DefaultSource() Source {
 		disable_host_node_id = true
 		disable_remote_exec = true
 		domain = "consul."
+		enable_central_service_config = true
 		encrypt_verify_incoming = true
 		encrypt_verify_outgoing = true
 		log_level = "INFO"

agent/config/runtime_test.go

@@ -4686,7 +4686,7 @@ func TestFullConfig(t *testing.T) {
 			},
 			"enable_acl_replication": true,
 			"enable_agent_tls_for_checks": true,
-			"enable_central_service_config": true,
+			"enable_central_service_config": false,
 			"enable_debug": true,
 			"enable_script_checks": true,
 			"enable_local_script_checks": true,
@@ -5351,7 +5351,7 @@ func TestFullConfig(t *testing.T) {
 			}
 			enable_acl_replication = true
 			enable_agent_tls_for_checks = true
-			enable_central_service_config = true
+			enable_central_service_config = false
 			enable_debug = true
 			enable_script_checks = true
 			enable_local_script_checks = true
@@ -6106,7 +6106,7 @@ func TestFullConfig(t *testing.T) {
 		DiscardCheckOutput:                     true,
 		DiscoveryMaxStale:                      5 * time.Second,
 		EnableAgentTLSForChecks:                true,
-		EnableCentralServiceConfig:             true,
+		EnableCentralServiceConfig:             false,
 		EnableDebug:                            true,
 		EnableRemoteScriptChecks:               true,
 		EnableLocalScriptChecks:                true,

agent/routine-leak-checker/leak_test.go

@@ -77,7 +77,6 @@ func setupPrimaryServer(t *testing.T) *agent.TestAgent {
 	   server = true
 		datacenter = "primary"
 		primary_datacenter = "primary"
-		enable_central_service_config = true
 		
 		connect {
 			enabled = true

agent/service_manager_test.go

@@ -17,7 +17,7 @@ import (
 func TestServiceManager_RegisterService(t *testing.T) {
 	require := require.New(t)
 
-	a := NewTestAgent(t, "enable_central_service_config = true")
+	a := NewTestAgent(t, "")
 	defer a.Shutdown()
 
 	testrpc.WaitForLeader(t, a.RPC, "dc1")
@@ -64,7 +64,7 @@ func TestServiceManager_RegisterService(t *testing.T) {
 func TestServiceManager_RegisterSidecar(t *testing.T) {
 	require := require.New(t)
 
-	a := NewTestAgent(t, "enable_central_service_config = true")
+	a := NewTestAgent(t, "")
 	defer a.Shutdown()
 
 	testrpc.WaitForLeader(t, a.RPC, "dc1")
@@ -151,7 +151,7 @@ func TestServiceManager_RegisterSidecar(t *testing.T) {
 func TestServiceManager_RegisterMeshGateway(t *testing.T) {
 	require := require.New(t)
 
-	a := NewTestAgent(t, "enable_central_service_config = true")
+	a := NewTestAgent(t, "")
 	defer a.Shutdown()
 
 	testrpc.WaitForLeader(t, a.RPC, "dc1")
@@ -207,7 +207,7 @@ func TestServiceManager_RegisterMeshGateway(t *testing.T) {
 func TestServiceManager_RegisterTerminatingGateway(t *testing.T) {
 	require := require.New(t)
 
-	a := NewTestAgent(t, "enable_central_service_config = true")
+	a := NewTestAgent(t, "")
 	defer a.Shutdown()
 
 	testrpc.WaitForLeader(t, a.RPC, "dc1")
@@ -268,7 +268,7 @@ func TestServiceManager_PersistService_API(t *testing.T) {
 	require := require.New(t)
 
 	// Launch a server to manage the config entries.
-	serverAgent := NewTestAgent(t, `enable_central_service_config = true`)
+	serverAgent := NewTestAgent(t, "")
 	defer serverAgent.Shutdown()
 	testrpc.WaitForLeader(t, serverAgent.RPC, "dc1")
 
@@ -293,7 +293,6 @@ func TestServiceManager_PersistService_API(t *testing.T) {
 
 	// Now launch a single client agent
 	cfg := `
-	    enable_central_service_config = true
 		server = false
 		bootstrap = false
 	`
@@ -481,7 +480,7 @@ func TestServiceManager_PersistService_ConfigFiles(t *testing.T) {
 	t.Parallel()
 
 	// Launch a server to manage the config entries.
-	serverAgent := NewTestAgent(t, `enable_central_service_config = true`)
+	serverAgent := NewTestAgent(t, "")
 	defer serverAgent.Shutdown()
 	testrpc.WaitForLeader(t, serverAgent.RPC, "dc1")
 
@@ -526,7 +525,6 @@ func TestServiceManager_PersistService_ConfigFiles(t *testing.T) {
 	`
 
 	cfg := `
-	    enable_central_service_config = true
 		server = false
 		bootstrap = false
 	` + serviceSnippet

test/integration/connect/envoy/case-centralconf/config_entries.hcl

@@ -1,4 +1,3 @@
-enable_central_service_config = true
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-resolver-dc-failover-gateways-none/primary/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "service-defaults"

test/integration/connect/envoy/case-cfg-resolver-dc-failover-gateways-remote/primary/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "service-defaults"

test/integration/connect/envoy/case-cfg-resolver-defaultsubset/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-resolver-features/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-resolver-subset-onlypassing/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-resolver-svc-failover/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-resolver-svc-redirect-http/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-resolver-svc-redirect-tcp/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-router-features/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-cfg-splitter-features/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "proxy-defaults"

test/integration/connect/envoy/case-ingress-gateway-grpc/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind     = "service-defaults"

test/integration/connect/envoy/case-ingress-gateway-http/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap = [
     {

test/integration/connect/envoy/case-ingress-gateway-multiple-services/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap = [
     {

test/integration/connect/envoy/case-ingress-gateway-simple/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "ingress-gateway"

test/integration/connect/envoy/case-ingress-gateway-tls/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap = [
     {

test/integration/connect/envoy/case-ingress-mesh-gateways-resolver/primary/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "ingress-gateway"

test/integration/connect/envoy/case-terminating-gateway-hostnames/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "terminating-gateway"

test/integration/connect/envoy/case-terminating-gateway-simple/config_entries.hcl

@@ -1,5 +1,3 @@
-enable_central_service_config = true
-
 config_entries {
   bootstrap {
     kind = "terminating-gateway"

website/pages/docs/agent/options.mdx

@@ -1464,6 +1464,7 @@ Valid time units are 'ns', 'us' (or 'µs'), 'ms', 's', 'm', 'h'."
 
 - `enable_central_service_config` When set, the Consul agent will look for any centralized service
   configurations that match a registering service instance. If it finds any, the agent will merge the centralized defaults with the service instance configuration. This allows for things like service protocol or proxy configuration to be defined centrally and inherited by any affected service registrations.
+  This defaults to `false` in versions of Consul prior to 1.9.0, and defaults to `true` in Consul 1.9.0 and later.
 
 - `enable_debug` When set, enables some additional debugging features. Currently, this is only used to
   access runtime profiling HTTP endpoints, which are available with an `operator:read` ACL regardless of the value of `enable_debug`.

website/pages/docs/upgrading/upgrade-specific.mdx

@@ -15,6 +15,11 @@ provided for their upgrades as a result of new features or changed behavior.
 This page is used to document those details separately from the standard
 upgrade flow.
 
+## Consul 1.9.0
+
+The [`enable_central_service_config`](/docs/agent/options#enable_central_service_config)
+configuration now defaults to `true`.
+
 ## Consul 1.8.0
 
 The [`acl_enforce_version_8`](/docs/agent/options#acl_enforce_version_8)