Optionally enable websocket compression

.config/example.yml

@@ -421,3 +421,7 @@ checkActivityPubGetSignature: false
   # How long to save each log entry before deleting it.
   # Default: 2592000000 (1 week)
   #maxAge: 2592000000
+
+# Transparently compress every websocket message on clients that support it.
+# Trades server CPU usage for reduced bandwidth usage and a faster frontend on the client.
+websocketCompression: false

packages/backend/src/config.ts

@@ -136,6 +136,8 @@ type Source = {
 		preSave?: boolean;
 		maxAge?: number;
 	};
+
+	websocketCompression?: boolean;
 };
 
 export type Config = {
@@ -252,6 +254,8 @@ export type Config = {
 		preSave: boolean;
 		maxAge: number;
 	};
+
+	websocketCompression?: boolean;
 };
 
 export type FulltextSearchProvider = 'sqlLike' | 'sqlPgroonga' | 'meilisearch' | 'sqlTsvector';
@@ -400,6 +404,7 @@ export function loadConfig(): Config {
 			preSave: config.activityLogging?.preSave ?? false,
 			maxAge: config.activityLogging?.maxAge ?? (1000 * 60 * 60 * 24 * 30),
 		},
+		websocketCompression: config.websocketCompression,
 	};
 }
 

packages/backend/src/server/api/StreamingApiServerService.ts

@@ -26,6 +26,7 @@ import MainStreamConnection from './stream/Connection.js';
 import { ChannelsService } from './stream/ChannelsService.js';
 import type * as http from 'node:http';
 import type { IEndpointMeta } from './endpoints.js';
+import type {Config} from "@/config.js";
 
 @Injectable()
 export class StreamingApiServerService {
@@ -49,6 +50,9 @@ export class StreamingApiServerService {
 		private channelFollowingService: ChannelFollowingService,
 		private rateLimiterService: SkRateLimiterService,
 		private loggerService: LoggerService,
+
+		@Inject(DI.config)
+		private config: Config,
 	) {
 	}
 
@@ -74,6 +78,7 @@ export class StreamingApiServerService {
 	public attach(server: http.Server): void {
 		this.#wss = new WebSocket.WebSocketServer({
 			noServer: true,
+			perMessageDeflate: this.config.websocketCompression ?? false,
 		});
 
 		server.on('upgrade', async (request, socket, head) => {