Add @vercel/static-config (vercel#6897)

.eslintignore

@@ -16,3 +16,4 @@ packages/node/src/bridge.ts
 packages/node/test/fixtures
 packages/node-bridge/bridge.js
 packages/node-bridge/launcher.js
+packages/static-config/test/fixtures

packages/static-config/.eslintignore

@@ -0,0 +1 @@
+test/fixtures

packages/static-config/.gitignore

@@ -0,0 +1 @@
+/dist

packages/static-config/package.json

@@ -0,0 +1,42 @@
+{
+  "name": "@vercel/static-config",
+  "version": "0.0.0",
+  "license": "MIT",
+  "main": "./dist/index",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/vercel/vercel.git",
+    "directory": "packages/static-config"
+  },
+  "scripts": {
+    "build": "tsc",
+    "test-unit": "jest",
+    "prepublishOnly": "tsc"
+  },
+  "files": [
+    "dist"
+  ],
+  "dependencies": {
+    "ajv": "8.6.3",
+    "json-schema-to-ts": "1.6.4",
+    "ts-morph": "12.0.0"
+  },
+  "devDependencies": {
+    "@types/jest": "27.0.2",
+    "@types/node": "*"
+  },
+  "jest": {
+    "preset": "ts-jest",
+    "globals": {
+      "ts-jest": {
+        "diagnostics": false,
+        "isolatedModules": true
+      }
+    },
+    "verbose": false,
+    "testEnvironment": "node",
+    "testMatch": [
+      "<rootDir>/test/**/*.test.ts"
+    ]
+  }
+}

packages/static-config/src/index.ts

@@ -0,0 +1,120 @@
+import {
+  Project,
+  SourceFile,
+  SyntaxKind,
+  NodeFlags,
+  ObjectLiteralExpression,
+  Node,
+  ArrayLiteralExpression,
+} from 'ts-morph';
+import Ajv from 'ajv';
+import { FromSchema, JSONSchema } from 'json-schema-to-ts';
+
+const ajv = new Ajv();
+
+export const BaseFunctionConfigSchema = {
+  type: 'object',
+  properties: {
+    runtime: { type: 'string' },
+    memory: { type: 'number' },
+    maxDuration: { type: 'number' },
+    regions: {
+      type: 'array',
+      items: { type: 'string' },
+    },
+  },
+} as const;
+
+export type BaseFunctionConfig = FromSchema<typeof BaseFunctionConfigSchema>;
+
+export function getConfig<
+  T extends JSONSchema = typeof BaseFunctionConfigSchema
+>(project: Project, sourcePath: string, schema?: T): FromSchema<T> | null {
+  const sourceFile = project.addSourceFileAtPath(sourcePath);
+  const configNode = getConfigNode(sourceFile);
+  if (!configNode) return null;
+  const config = getValue(configNode);
+  // @ts-ignore
+  return validate(schema || BaseFunctionConfigSchema, config);
+}
+
+function validate<T>(schema: T, data: any): FromSchema<T> {
+  const isValid = ajv.compile(schema);
+  if (!isValid(data)) {
+    // TODO: better error message
+    throw new Error('Invalid data');
+  }
+  return data as FromSchema<T>;
+}
+
+function getConfigNode(sourceFile: SourceFile) {
+  return sourceFile
+    .getDescendantsOfKind(SyntaxKind.ObjectLiteralExpression)
+    .find(objectLiteral => {
+      // Make sure the object is assigned to "config"
+      const varDec = objectLiteral.getParentIfKind(
+        SyntaxKind.VariableDeclaration
+      );
+      if (varDec?.getName() !== 'config') return false;
+
+      // Make sure assigned with `const`
+      const varDecList = varDec.getParentIfKind(
+        SyntaxKind.VariableDeclarationList
+      );
+      const isConst = (varDecList?.getFlags() ?? 0) & NodeFlags.Const;
+      if (!isConst) return false;
+
+      // Make sure it is exported
+      const exp = varDecList?.getParentIfKind(SyntaxKind.VariableStatement);
+      if (!exp?.isExported()) return false;
+
+      return true;
+    });
+}
+
+function getValue(valueNode: Node): unknown {
+  if (Node.isStringLiteral(valueNode)) {
+    return eval(valueNode.getText());
+  } else if (Node.isNumericLiteral(valueNode)) {
+    return Number(valueNode.getText());
+  } else if (Node.isTrueLiteral(valueNode)) {
+    return true;
+  } else if (Node.isFalseLiteral(valueNode)) {
+    return false;
+  } else if (Node.isNullLiteral(valueNode)) {
+    return null;
+  } else if (Node.isArrayLiteralExpression(valueNode)) {
+    return getArray(valueNode);
+  } else if (Node.isObjectLiteralExpression(valueNode)) {
+    return getObject(valueNode);
+  } else if (
+    Node.isIdentifier(valueNode) &&
+    valueNode.getText() === 'undefined'
+  ) {
+    return undefined;
+  }
+  throw new Error(
+    `Unhandled type: "${valueNode.getKindName()}" ${valueNode.getText()}`
+  );
+}
+
+function getObject(obj: ObjectLiteralExpression): unknown {
+  const rtn: { [v: string]: unknown } = {};
+  for (const prop of obj.getProperties()) {
+    if (!Node.isPropertyAssignment(prop)) continue;
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    const [nameNode, _colon, valueNode] = prop.getChildren();
+    const name = nameNode.getText();
+    rtn[name] = getValue(valueNode);
+  }
+  return rtn;
+}
+
+function getArray(arr: ArrayLiteralExpression): unknown {
+  const elementNodes = arr.getElements();
+  const rtn = new Array(elementNodes.length);
+  for (let i = 0; i < elementNodes.length; i++) {
+    rtn[i] = getValue(elementNodes[i]);
+  }
+  return rtn;
+}

packages/static-config/test/fixtures/deno.ts

@@ -0,0 +1,11 @@
+import ms from 'https://denopkg.com/TooTallNate/ms';
+import { readerFromStreamReader } from 'https://deno.land/std@0.107.0/io/streams.ts';
+
+export const config = {
+  runtime: 'deno',
+  location: 'https://example.com/page',
+};
+
+export default async ({ request }: Deno.RequestEvent) => {
+  return new Response('Hello from Deno');
+};

packages/static-config/test/fixtures/invalid-schema.js

@@ -0,0 +1,3 @@
+export const config = {
+  runtime: 0,
+};

packages/static-config/test/fixtures/no-config.js

@@ -0,0 +1 @@
+export const foo = 'bar';

packages/static-config/test/fixtures/node.js

@@ -0,0 +1,10 @@
+import fs from 'fs';
+
+export const config = {
+  runtime: 'node',
+  memory: 1024,
+};
+
+export default function (req, res) {
+  res.end('Hi from Node');
+}

packages/static-config/test/index.test.ts

@@ -0,0 +1,53 @@
+import { join } from 'path';
+import { Project } from 'ts-morph';
+import { getConfig } from '../src';
+
+describe('getConfig()', () => {
+  it('should parse config from Node.js file', () => {
+    const project = new Project();
+    const sourcePath = join(__dirname, 'fixtures/node.js');
+    const config = getConfig(project, sourcePath);
+    expect(config).toMatchInlineSnapshot(`
+      Object {
+        "memory": 1024,
+        "runtime": "node",
+      }
+    `);
+  });
+
+  it('should parse config from Deno file', () => {
+    const project = new Project();
+    const sourcePath = join(__dirname, 'fixtures/deno.ts');
+    const config = getConfig(project, sourcePath, {
+      type: 'object',
+      properties: {
+        location: { type: 'string' },
+      },
+    } as const);
+    expect(config).toMatchInlineSnapshot(`
+      Object {
+        "location": "https://example.com/page",
+        "runtime": "deno",
+      }
+    `);
+  });
+
+  it('should return `null` when no config was exported', () => {
+    const project = new Project();
+    const sourcePath = join(__dirname, 'fixtures/no-config.js');
+    const config = getConfig(project, sourcePath);
+    expect(config).toBeNull();
+  });
+
+  it('should throw an error upon schema validation failure', () => {
+    const project = new Project();
+    const sourcePath = join(__dirname, 'fixtures/invalid-schema.js');
+    let err;
+    try {
+      getConfig(project, sourcePath);
+    } catch (_err) {
+      err = _err;
+    }
+    expect(err.message).toEqual('Invalid data');
+  });
+});

packages/static-config/test/tsconfig.json

@@ -0,0 +1,4 @@
+{
+  "extends": "../tsconfig.json",
+  "include": ["*.test.ts"]
+}

packages/static-config/tsconfig.json

@@ -0,0 +1,16 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "esModuleInterop": true,
+    "lib": ["esnext"],
+    "target": "es2018",
+    "module": "commonjs",
+    "outDir": "dist",
+    "sourceMap": true,
+    "declaration": true,
+    "moduleResolution": "node",
+    "typeRoots": ["./@types", "./node_modules/@types"]
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules"]
+}