WebSocketEventSource

Source: src/AWS/ApiGatewayV2/WebSocketEventSource.ts

Event source connecting a WebSocket Api route to the hosting Lambda function.

At deploy time the Lambda implementation (Lambda.WebSocketEventSource) materializes the Integration, Route, and invoke Permission for the route; at runtime it dispatches matching WebSocket proxy events to the handler. Subscribe routes with onWebSocketRoute and provide Lambda.WebSocketEventSource on the hosting function.

Handling WebSocket Routes

export default MyFunction.make(
  { main: import.meta.url },
  Effect.gen(function* () {
    const api = yield* ApiGatewayV2.Api("WsApi", {
      protocolType: "WEBSOCKET",
      routeSelectionExpression: "$request.body.action",
    });
    const stage = yield* ApiGatewayV2.Stage("WsStage", {
      api,
      stageName: "prod",
      autoDeploy: true,
    });
    const connections = yield* ApiGatewayV2.ManageConnections(stage);

    yield* ApiGatewayV2.onWebSocketRoute(api, { routeKey: "$connect" }, () =>
      Effect.succeed({ statusCode: 200 }),
    );

    yield* ApiGatewayV2.onWebSocketRoute(api, { routeKey: "$default" }, (event) =>
      connections
        .postToConnection({
          ConnectionId: event.requestContext.connectionId,
          Data: `echo:${event.body ?? ""}`,
        })
        .pipe(
          Effect.asVoid,
          Effect.catchTag("GoneException", () => Effect.void),
          Effect.orDie,
        ),
    );

    return {};
  }).pipe(
    Effect.provide(
      Layer.mergeAll(
        Lambda.WebSocketEventSource,
        ApiGatewayV2.ManageConnectionsHttp,
      ),
    ),
  ),
);