# packages/client-runtime/src/connection/driver.ts ยท gitcafe/t3code [View on GitCafe](https://git.cafe/gitcafe/t3code/blob/4d976d1fc233d3aa971fa7dcbf2e7316bfa3ac72/packages/client-runtime/src/connection/driver.ts) Repository: [gitcafe/t3code](https://git.cafe/gitcafe/t3code) Visibility: public Requested revision: 4d976d1fc233d3aa971fa7dcbf2e7316bfa3ac72 Requested commit: 4d976d1fc233d3aa971fa7dcbf2e7316bfa3ac72 Commit: 4d976d1fc233d3aa971fa7dcbf2e7316bfa3ac72 Blob: d34bc1a9ba49a4efbaae9d96c3dbc2f7b23a401f Size: 8191 bytes [Immutable source](https://git.cafe/gitcafe/t3code/blob/4d976d1fc233d3aa971fa7dcbf2e7316bfa3ac72/packages/client-runtime/src/connection/driver.ts?format=markdown) ``` import * as Context from "effect/Context"; import * as Effect from "effect/Effect"; import * as Exit from "effect/Exit"; import * as Fiber from "effect/Fiber"; import * as Layer from "effect/Layer"; import * as Scope from "effect/Scope"; import * as HttpClient from "effect/http/HttpClient"; import type { ConnectionCatalogEntry, ConnectionRoute } from "./catalog.ts"; import type { ConnectionAttemptError, ConnectionAttemptStage, PreparedConnection, } from "./model.ts"; import { ConnectionTransientError } from "./model.ts"; import * as ConnectionResolver from "./resolver.ts"; import { connectionRoutes, routeEntry, routeHttpBaseUrl } from "./routes.ts"; import * as RpcSession from "../rpc/session.ts"; import { fetchRemoteEnvironmentDescriptor } from "../environment/descriptor.ts"; export type ConnectionDriverProgress = | { readonly stage: "preparing"; } | { readonly stage: Exclude; readonly prepared: PreparedConnection; }; export interface EnvironmentConnectionLease { readonly prepared: PreparedConnection; readonly session: RpcSession.RpcSession; } /** * The result of an unauthenticated reachability check. T3 Connect and SSH * routes have no cheap check, so they are "unchecked". */ export type RouteCheck = "answered" | "silent" | "unchecked"; /** How long a direct route has to answer before it counts as unreachable from here. */ const ROUTE_CHECK_TIMEOUT_MS = 2_500; export class ConnectionDriver extends Context.Service< ConnectionDriver, { readonly connect: ( entry: ConnectionCatalogEntry, reportProgress: (progress: ConnectionDriverProgress) => Effect.Effect, ) => Effect.Effect; /** Whether a direct route answers as the entry's environment, without credentials. */ readonly checkRoute: ( entry: ConnectionCatalogEntry, route: ConnectionRoute, ) => Effect.Effect; /** * Whether a direct route answers and accepts this client's credential, * without opening a socket. Switching to a route that fails this would * drop a working connection for nothing. */ readonly preflight: ( entry: ConnectionCatalogEntry, route: ConnectionRoute, ) => Effect.Effect; } >()("@t3tools/client-runtime/connection/driver/ConnectionDriver") {} /** * Connects over the first route, in preference order, that is worth trying. * Every route is checked at once, but a route only waits for its own check, * so a reachable LAN address connects without waiting on a silent tailnet * one. A silent route is skipped on the first pass so a LAN address from * another network costs one short check, not a connection timeout. A route * that fails to connect moves on to the next: a signed-out T3 Connect must * not hide a working LAN. Silent routes are tried last, since a check is not * proof. * * The reported error is a transient one when any route failed transiently, * so the supervisor keeps retrying a route that may come back; a blocked * error is reported only when every attempted route was blocked. */ export const connectOverRoutes = Effect.fn("ConnectionDriver.connectOverRoutes")(function* ( entry: ConnectionCatalogEntry, checkRoute: (route: ConnectionRoute) => Effect.Effect, connectRoute: ( route: ConnectionRoute, ) => Effect.Effect, ) { const routes = connectionRoutes(entry); const checks = routes.length === 1 ? [] : yield* Effect.forEach(routes, (route) => Effect.forkChild(checkRoute(route))); const attemptScope = yield* Scope.Scope; let transient: ConnectionAttemptError | undefined; let blocked: ConnectionAttemptError | undefined; // Each route gets its own scope so a half-open session closes before the next try. const attempt = Effect.fnUntraced(function* (route: ConnectionRoute) { const routeScope = yield* Scope.fork(attemptScope); const result = yield* connectRoute(route).pipe( Scope.provide(routeScope), Effect.onExit((exit) => (Exit.isSuccess(exit) ? Effect.void : Scope.close(routeScope, exit))), Effect.result, ); if (result._tag === "Failure") { if (result.failure._tag === "ConnectionTransientError") transient ??= result.failure; else blocked ??= result.failure; } return result; }); const silent: Array = []; for (const [index, route] of routes.entries()) { const check = checks.length === 0 ? "unchecked" : yield* Fiber.join(checks[index]!); if (check === "silent") { silent.push(route); continue; } const result = yield* attempt(route); if (result._tag === "Success") return result.success; // An incompatible server is the same server on every route. if (result.failure.reason === "unsupported") return yield* result.failure; } for (const route of silent) { const result = yield* attempt(route); if (result._tag === "Success") return result.success; if (result.failure.reason === "unsupported") return yield* result.failure; } return yield* ( transient ?? blocked ?? new ConnectionTransientError({ reason: "endpoint-unavailable", detail: `${entry.target.label} did not answer on any saved route.`, }) ); }); /** @public Service construction is part of the canonical Effect module API. */ export const make = Effect.gen(function* () { const resolver = yield* ConnectionResolver.ConnectionResolver; const sessions = yield* RpcSession.RpcSessionFactory; const httpClient = yield* HttpClient.HttpClient; const checkRoute = (entry: ConnectionCatalogEntry, route: ConnectionRoute) => { const httpBaseUrl = routeHttpBaseUrl(route); if (httpBaseUrl === null) return Effect.succeed("unchecked"); // The descriptor is public, so this sends no credential to whatever // answers at a saved LAN address on a different network. return fetchRemoteEnvironmentDescriptor({ httpBaseUrl, timeoutMs: ROUTE_CHECK_TIMEOUT_MS, }).pipe( Effect.map((descriptor): RouteCheck => descriptor.environmentId === entry.target.environmentId ? "answered" : "silent", ), Effect.orElseSucceed((): RouteCheck => "silent"), Effect.provideService(HttpClient.HttpClient, httpClient), Effect.withSpan("ConnectionDriver.checkRoute", { attributes: { "connection.target.kind": route.target._tag }, }), ); }; const connect = Effect.fn("ConnectionDriver.connect")(function* ( entry: ConnectionCatalogEntry, reportProgress: (progress: ConnectionDriverProgress) => Effect.Effect, ) { const target = entry.target; yield* Effect.annotateCurrentSpan({ "connection.environment.id": target.environmentId, "connection.target.kind": target._tag, "connection.route.count": connectionRoutes(entry).length, }); yield* reportProgress({ stage: "preparing" }); return yield* connectOverRoutes( entry, (route) => checkRoute(entry, route), Effect.fnUntraced(function* (route) { const prepared = yield* resolver.prepare(routeEntry(entry, route)); yield* reportProgress({ stage: "opening", prepared }); const session = yield* sessions.connect(prepared); yield* reportProgress({ stage: "synchronizing", prepared }); yield* session.ready; return { prepared, session } satisfies EnvironmentConnectionLease; }), ); }); const preflight = (entry: ConnectionCatalogEntry, route: ConnectionRoute) => checkRoute(entry, route).pipe( Effect.flatMap((check) => check === "answered" ? resolver.prepare(routeEntry(entry, route)).pipe( Effect.as(true), Effect.orElseSucceed(() => false), ) : Effect.succeed(false), ), Effect.withSpan("ConnectionDriver.preflight"), ); return ConnectionDriver.of({ connect, checkRoute, preflight }); }); export const layer = Layer.effect(ConnectionDriver, make); ```