Remove polylith/API mode (#2967)

This removes most of the code used for polylith/API mode.

This removes the `/api` internal endpoints entirely. 

Binary size change roughly 5%: 
```
51437560 Feb 13 10:15 dendrite-monolith-server # old
48759008 Feb 13 10:15 dendrite-monolith-server # new
```

4 files changed, 1 insertions, 148 deletions

diff --git a/appservice/appservice.go b/appservice/appservice.go
index 753850de..b950a821 100644
--- a/appservice/appservice.go
+++ b/appservice/appservice.go
@@ -21,14 +21,12 @@ import (
 	"sync"
 	"time"
 
-	"github.com/gorilla/mux"
 	"github.com/sirupsen/logrus"
 
 	"github.com/matrix-org/gomatrixserverlib"
 
 	appserviceAPI "github.com/matrix-org/dendrite/appservice/api"
 	"github.com/matrix-org/dendrite/appservice/consumers"
-	"github.com/matrix-org/dendrite/appservice/inthttp"
 	"github.com/matrix-org/dendrite/appservice/query"
 	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/setup/base"
@@ -36,11 +34,6 @@ import (
 	userapi "github.com/matrix-org/dendrite/userapi/api"
 )
 
-// AddInternalRoutes registers HTTP handlers for internal API calls
-func AddInternalRoutes(router *mux.Router, queryAPI appserviceAPI.AppServiceInternalAPI, enableMetrics bool) {
-	inthttp.AddRoutes(queryAPI, router, enableMetrics)
-}
-
 // NewInternalAPI returns a concerete implementation of the internal API. Callers
 // can call functions directly on the returned API or via an HTTP interface using AddInternalRoutes.
 func NewInternalAPI(
diff --git a/appservice/appservice_test.go b/appservice/appservice_test.go
index 83c551fe..9e9940cd 100644
--- a/appservice/appservice_test.go
+++ b/appservice/appservice_test.go
@@ -10,12 +10,8 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/gorilla/mux"
-
 	"github.com/matrix-org/dendrite/appservice"
 	"github.com/matrix-org/dendrite/appservice/api"
-	"github.com/matrix-org/dendrite/appservice/inthttp"
-	"github.com/matrix-org/dendrite/internal/httputil"
 	"github.com/matrix-org/dendrite/roomserver"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/test"
@@ -132,23 +128,7 @@ func TestAppserviceInternalAPI(t *testing.T) {
 		usrAPI := userapi.NewInternalAPI(base, &base.Cfg.UserAPI, nil, nil, rsAPI, nil)
 		asAPI := appservice.NewInternalAPI(base, usrAPI, rsAPI)
 
-		// Finally execute the tests
-		t.Run("HTTP API", func(t *testing.T) {
-			router := mux.NewRouter().PathPrefix(httputil.InternalPathPrefix).Subrouter()
-			appservice.AddInternalRoutes(router, asAPI, base.EnableMetrics)
-			apiURL, cancel := test.ListenAndServe(t, router, false)
-			defer cancel()
-
-			asHTTPApi, err := inthttp.NewAppserviceClient(apiURL, &http.Client{})
-			if err != nil {
-				t.Fatalf("failed to create HTTP client: %s", err)
-			}
-			runCases(t, asHTTPApi)
-		})
-
-		t.Run("Monolith", func(t *testing.T) {
-			runCases(t, asAPI)
-		})
+		runCases(t, asAPI)
 	})
 }
 
diff --git a/appservice/inthttp/client.go b/appservice/inthttp/client.go
deleted file mode 100644
index f7f16487..00000000
--- a/appservice/inthttp/client.go
+++ /dev/null
@@ -1,84 +0,0 @@
-package inthttp
-
-import (
-	"context"
-	"errors"
-	"net/http"
-
-	"github.com/matrix-org/dendrite/appservice/api"
-	"github.com/matrix-org/dendrite/internal/httputil"
-)
-
-// HTTP paths for the internal HTTP APIs
-const (
-	AppServiceRoomAliasExistsPath = "/appservice/RoomAliasExists"
-	AppServiceUserIDExistsPath    = "/appservice/UserIDExists"
-	AppServiceLocationsPath       = "/appservice/locations"
-	AppServiceUserPath            = "/appservice/users"
-	AppServiceProtocolsPath       = "/appservice/protocols"
-)
-
-// httpAppServiceQueryAPI contains the URL to an appservice query API and a
-// reference to a httpClient used to reach it
-type httpAppServiceQueryAPI struct {
-	appserviceURL string
-	httpClient    *http.Client
-}
-
-// NewAppserviceClient creates a AppServiceQueryAPI implemented by talking
-// to a HTTP POST API.
-// If httpClient is nil an error is returned
-func NewAppserviceClient(
-	appserviceURL string,
-	httpClient *http.Client,
-) (api.AppServiceInternalAPI, error) {
-	if httpClient == nil {
-		return nil, errors.New("NewRoomserverAliasAPIHTTP: httpClient is <nil>")
-	}
-	return &httpAppServiceQueryAPI{appserviceURL, httpClient}, nil
-}
-
-// RoomAliasExists implements AppServiceQueryAPI
-func (h *httpAppServiceQueryAPI) RoomAliasExists(
-	ctx context.Context,
-	request *api.RoomAliasExistsRequest,
-	response *api.RoomAliasExistsResponse,
-) error {
-	return httputil.CallInternalRPCAPI(
-		"RoomAliasExists", h.appserviceURL+AppServiceRoomAliasExistsPath,
-		h.httpClient, ctx, request, response,
-	)
-}
-
-// UserIDExists implements AppServiceQueryAPI
-func (h *httpAppServiceQueryAPI) UserIDExists(
-	ctx context.Context,
-	request *api.UserIDExistsRequest,
-	response *api.UserIDExistsResponse,
-) error {
-	return httputil.CallInternalRPCAPI(
-		"UserIDExists", h.appserviceURL+AppServiceUserIDExistsPath,
-		h.httpClient, ctx, request, response,
-	)
-}
-
-func (h *httpAppServiceQueryAPI) Locations(ctx context.Context, request *api.LocationRequest, response *api.LocationResponse) error {
-	return httputil.CallInternalRPCAPI(
-		"ASLocation", h.appserviceURL+AppServiceLocationsPath,
-		h.httpClient, ctx, request, response,
-	)
-}
-
-func (h *httpAppServiceQueryAPI) User(ctx context.Context, request *api.UserRequest, response *api.UserResponse) error {
-	return httputil.CallInternalRPCAPI(
-		"ASUser", h.appserviceURL+AppServiceUserPath,
-		h.httpClient, ctx, request, response,
-	)
-}
-
-func (h *httpAppServiceQueryAPI) Protocols(ctx context.Context, request *api.ProtocolRequest, response *api.ProtocolResponse) error {
-	return httputil.CallInternalRPCAPI(
-		"ASProtocols", h.appserviceURL+AppServiceProtocolsPath,
-		h.httpClient, ctx, request, response,
-	)
-}
diff --git a/appservice/inthttp/server.go b/appservice/inthttp/server.go
deleted file mode 100644
index b70fad67..00000000
--- a/appservice/inthttp/server.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package inthttp
-
-import (
-	"github.com/gorilla/mux"
-
-	"github.com/matrix-org/dendrite/appservice/api"
-	"github.com/matrix-org/dendrite/internal/httputil"
-)
-
-// AddRoutes adds the AppServiceQueryAPI handlers to the http.ServeMux.
-func AddRoutes(a api.AppServiceInternalAPI, internalAPIMux *mux.Router, enableMetrics bool) {
-	internalAPIMux.Handle(
-		AppServiceRoomAliasExistsPath,
-		httputil.MakeInternalRPCAPI("AppserviceRoomAliasExists", enableMetrics, a.RoomAliasExists),
-	)
-
-	internalAPIMux.Handle(
-		AppServiceUserIDExistsPath,
-		httputil.MakeInternalRPCAPI("AppserviceUserIDExists", enableMetrics, a.UserIDExists),
-	)
-
-	internalAPIMux.Handle(
-		AppServiceProtocolsPath,
-		httputil.MakeInternalRPCAPI("AppserviceProtocols", enableMetrics, a.Protocols),
-	)
-
-	internalAPIMux.Handle(
-		AppServiceLocationsPath,
-		httputil.MakeInternalRPCAPI("AppserviceLocations", enableMetrics, a.Locations),
-	)
-
-	internalAPIMux.Handle(
-		AppServiceUserPath,
-		httputil.MakeInternalRPCAPI("AppserviceUser", enableMetrics, a.User),
-	)
-}