feat: add stream helper

.github/workflows/workflow.yml

@@ -13,12 +13,12 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        node-version: [8.17.0, '*']
+        node-version: [14.0.0, '*']
         exclude:
           - os: macOS-latest
-            node-version: 8.17.0
+            node-version: 14.0.0
           - os: windows-latest
-            node-version: 8.17.0
+            node-version: 14.0.0
       fail-fast: false
     steps:
       - name: Git checkout

package.json

@@ -66,6 +66,6 @@
     "typescript": "^4.4.4"
   },
   "engines": {
-    "node": ">=8.3.0"
+    "node": ">=14.0.0"
   }
 }

src/function/handler.ts

@@ -1,6 +1,6 @@
 import type { Context } from './context.js'
 import type { Event } from './event.js'
-import type { Response, BuilderResponse } from './response.js'
+import type { Response, BuilderResponse, StreamingResponse } from './response.js'
 
 export interface HandlerCallback<ResponseType extends Response = Response> {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -17,3 +17,7 @@ export interface BackgroundHandler<C extends Context = Context> {
 
 export type Handler = BaseHandler<Response, Context>
 export type BuilderHandler = BaseHandler<BuilderResponse, Context>
+
+export interface StreamingHandler {
+  (event: Event, context: Context): Promise<StreamingResponse>
+}

src/function/index.ts

@@ -1,6 +1,6 @@
 export { Context as HandlerContext } from './context.js'
 export { Event as HandlerEvent } from './event.js'
-export { BuilderHandler, Handler, BackgroundHandler, HandlerCallback } from './handler.js'
+export { BuilderHandler, Handler, BackgroundHandler, HandlerCallback, StreamingHandler } from './handler.js'
 export { BuilderResponse, Response as HandlerResponse } from './response.js'
 export {
   getSecrets,

src/function/response.ts

@@ -12,3 +12,7 @@ export interface Response {
 export interface BuilderResponse extends Response {
   ttl?: number
 }
+
+export interface StreamingResponse extends Omit<Response, 'body'> {
+  body?: string | NodeJS.ReadableStream
+}

src/lib/secrets_helper.ts

@@ -146,7 +146,6 @@ const findLoggedInServicesQuery = `query FindLoggedInServicesQuery {
 const getSecretsForToken = async (token: string): Promise<NetlifySecrets> => {
   const body = JSON.stringify({ query: findLoggedInServicesQuery })
 
-  // eslint-disable-next-line n/no-unsupported-features/node-builtins
   const resultBody = await graphRequest(token, new TextEncoder().encode(body))
   const result: GraphSecretsResponse = JSON.parse(resultBody)
 

src/lib/stream.ts

@@ -0,0 +1,55 @@
+import { pipeline } from 'stream'
+
+import type { Handler, HandlerEvent, HandlerContext, HandlerResponse, StreamingHandler } from '../function/index.js'
+
+declare global {
+  // eslint-disable-next-line @typescript-eslint/no-namespace
+  namespace awslambda {
+    function streamifyResponse(
+      handler: (
+        event: HandlerEvent,
+        responseStream: NodeJS.WritableStream,
+        context: HandlerContext,
+      ) => Promise<HandlerResponse>,
+    ): Handler
+  }
+}
+
+/**
+ * Enables streaming responses.
+ *
+ * @example
+ * ```
+ * const { Readable } = require('stream');
+ *
+ * export const handler = stream(async (event, context) => {
+ *   const stream = Readable.from(Buffer.from(JSON.stringify(event)))
+ *   return {
+ *     statusCode: 200,
+ *     body: stream,
+ *   }
+ * })
+ * ```
+ *
+ * @param handler
+ * @see https://ntl.fyi/streaming-func
+ */
+const stream = (handler: StreamingHandler): Handler =>
+  awslambda.streamifyResponse(async (event, responseStream, context) => {
+    const { body, ...rest } = await handler(event, context)
+
+    if (typeof body === 'undefined' || typeof body === 'string') {
+      return {
+        body,
+        ...rest,
+      }
+    }
+
+    pipeline(body, responseStream)
+
+    return {
+      ...rest,
+    }
+  })
+
+export { stream }

src/main.ts

@@ -1,3 +1,4 @@
 export { builder } from './lib/builder.js'
 export { schedule } from './lib/schedule.js'
+export { stream } from './lib/stream.js'
 export * from './function/index.js'

tsconfig.json

@@ -11,7 +11,7 @@
     // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */
 
     /* Language and Environment */
-    "target": "es5" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
+    "target": "ES2020" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
     // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
     // "jsx": "preserve",                                /* Specify what JSX code is generated. */
     // "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */