fix: missing MaxInboundConnections field in service-defaults config entry (#14072)

* fix:  missing max_inbound_connections field in merge config

agent/consul/merge_service_config.go

@@ -159,6 +159,13 @@ func computeResolvedServiceConfig(
 			thisReply.Destination = *serviceConf.Destination
 		}
 
+		if serviceConf.MaxInboundConnections > 0 {
+			if thisReply.ProxyConfig == nil {
+				thisReply.ProxyConfig = map[string]interface{}{}
+			}
+			thisReply.ProxyConfig["max_inbound_connections"] = serviceConf.MaxInboundConnections
+		}
+
 		thisReply.Meta = serviceConf.Meta
 	}
 

agent/consul/merge_service_config_test.go

@@ -3,12 +3,59 @@ package consul
 import (
 	"testing"
 
+	"github.com/hashicorp/consul/agent/configentry"
 	"github.com/hashicorp/consul/agent/structs"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+func Test_ComputeResolvedServiceConfig(t *testing.T) {
+	type args struct {
+		scReq       *structs.ServiceConfigRequest
+		upstreamIDs []structs.ServiceID
+		entries     *configentry.ResolvedServiceConfigSet
+	}
+
+	sid := structs.ServiceID{
+		ID: "sid",
+	}
+	tests := []struct {
+		name string
+		args args
+		want *structs.ServiceConfigResponse
+	}{
+		{
+			name: "proxy with maxinboundsconnections",
+			args: args{
+				scReq: &structs.ServiceConfigRequest{
+					Name: "sid",
+				},
+				entries: &configentry.ResolvedServiceConfigSet{
+					ServiceDefaults: map[structs.ServiceID]*structs.ServiceConfigEntry{
+						sid: {
+							MaxInboundConnections: 20,
+						},
+					},
+				},
+			},
+			want: &structs.ServiceConfigResponse{
+				ProxyConfig: map[string]interface{}{
+					"max_inbound_connections": 20,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := computeResolvedServiceConfig(tt.args.scReq, tt.args.upstreamIDs,
+				false, tt.args.entries, nil)
+			require.NoError(t, err)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
 func Test_MergeServiceConfig_TransparentProxy(t *testing.T) {
 	type args struct {
 		defaults *structs.ServiceConfigResponse

agent/structs/config_entry_test.go

@@ -216,6 +216,85 @@ func testConfigEntries_ListRelatedServices_AndACLs(t *testing.T, cases []configE
 	}
 }
 
+func TestDecodeConfigEntry_ServiceDefaults(t *testing.T) {
+
+	for _, tc := range []struct {
+		name      string
+		camel     string
+		snake     string
+		expect    ConfigEntry
+		expectErr string
+	}{
+		{
+			name: "service-defaults-with-MaxInboundConnections",
+			snake: `
+				kind = "service-defaults"
+				name = "external"
+				protocol = "tcp"
+				destination {
+					addresses = [
+						"api.google.com",
+						"web.google.com"
+					]
+					port = 8080
+				}
+				max_inbound_connections = 14
+			`,
+			camel: `
+				Kind = "service-defaults"
+				Name = "external"
+				Protocol = "tcp"
+				Destination {
+					Addresses = [
+						"api.google.com",
+						"web.google.com"
+					]
+					Port = 8080
+				}
+				MaxInboundConnections = 14
+			`,
+			expect: &ServiceConfigEntry{
+				Kind:     "service-defaults",
+				Name:     "external",
+				Protocol: "tcp",
+				Destination: &DestinationConfig{
+					Addresses: []string{
+						"api.google.com",
+						"web.google.com",
+					},
+					Port: 8080,
+				},
+				MaxInboundConnections: 14,
+			},
+		},
+	} {
+		tc := tc
+
+		testbody := func(t *testing.T, body string) {
+			var raw map[string]interface{}
+			err := hcl.Decode(&raw, body)
+			require.NoError(t, err)
+
+			got, err := DecodeConfigEntry(raw)
+			if tc.expectErr != "" {
+				require.Nil(t, got)
+				require.Error(t, err)
+				requireContainsLower(t, err.Error(), tc.expectErr)
+			} else {
+				require.NoError(t, err)
+				require.Equal(t, tc.expect, got)
+			}
+		}
+
+		t.Run(tc.name+" (snake case)", func(t *testing.T) {
+			testbody(t, tc.snake)
+		})
+		t.Run(tc.name+" (camel case)", func(t *testing.T) {
+			testbody(t, tc.camel)
+		})
+	}
+}
+
 // TestDecodeConfigEntry is the 'structs' mirror image of
 // command/config/write/config_write_test.go:TestParseConfigEntry
 func TestDecodeConfigEntry(t *testing.T) {

api/config_entry.go

@@ -230,6 +230,7 @@ type ServiceConfigEntry struct {
 	ExternalSNI           string                  `json:",omitempty" alias:"external_sni"`
 	UpstreamConfig        *UpstreamConfiguration  `json:",omitempty" alias:"upstream_config"`
 	Destination           *DestinationConfig      `json:",omitempty"`
+	MaxInboundConnections int                     `json:",omitempty" alias:"max_inbound_connections"`
 	Meta                  map[string]string       `json:",omitempty"`
 	CreateIndex           uint64
 	ModifyIndex           uint64

api/config_entry_test.go

@@ -104,6 +104,7 @@ func TestAPI_ConfigEntries(t *testing.T) {
 				"foo": "bar",
 				"gir": "zim",
 			},
+			MaxInboundConnections: 5,
 		}
 
 		dest := &DestinationConfig{
@@ -144,6 +145,7 @@ func TestAPI_ConfigEntries(t *testing.T) {
 		require.Equal(t, service.Protocol, readService.Protocol)
 		require.Equal(t, service.Meta, readService.Meta)
 		require.Equal(t, service.Meta, readService.GetMeta())
+		require.Equal(t, service.MaxInboundConnections, readService.MaxInboundConnections)
 
 		// update it
 		service.Protocol = "tcp"

website/content/docs/connect/config-entries/service-defaults.mdx

@@ -687,6 +687,12 @@ represents a location outside the Consul cluster. They can be dialed directly wh
         },
       ]
     },
+    {
+      name: 'MaxInboundConnections',
+      description: 'The maximum number of concurrent inbound connections to each service instance.',
+      type: 'int: 0',
+      yaml: true,
+    },
     {
       name: 'MeshGateway',
       type: 'MeshGatewayConfig: <optional>',