BREAKING: Break TS build that uses functions.config() #1757

taeold · 2025-10-30T01:56:58Z

Type out functions.config() API. Use of functions.config() API should now cause a BUILD error at compile time.

import * as functions from "firebase-functions";
import {onRequest} from "firebase-functions/https";
import * as logger from "firebase-functions/logger";

const cfg = functions.config()

export const helloWorld = onRequest((request, response) => {
  logger.info("Hello logs!", cfg);
  response.send("Hello from Firebase!");
});

$ npm run build

> build
> tsc

src/index.ts:5:23 - error TS2349: This expression is not callable.
  Type 'never' has no call signatures.

5 const cfg = functions.config()
                        ~~~~~~


Found 1 error in src/index.ts:5

gemini-code-assist · 2025-10-30T01:57:11Z

Summary of Changes

Hello @taeold, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant breaking change by modifying the TypeScript definition of the functions.config() API. The primary goal is to enforce the deprecation of this API at compile time, preventing its accidental use and directing developers towards the recommended environment parameters module. This ensures that projects using firebase-functions v7 or later will encounter a build error if they have not yet migrated away from functions.config(), thereby promoting adherence to the new configuration management practices.

Highlights

Breaking Change: The functions.config() API is now explicitly typed as never in TypeScript, causing a compile-time build error if used.
Compile-Time Enforcement: This change ensures that any usage of the deprecated functions.config() will result in a build error, guiding developers to migrate to environment parameters.
Runtime Behavior: The runtime behavior remains consistent: calling functions.config() will still throw an error with a clear migration message.

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Code Review

This pull request introduces a breaking change to make functions.config() cause a TypeScript build error upon use. This is achieved by re-typing config as never, which correctly prevents its usage in TypeScript projects at compile time. The runtime behavior is preserved, where a call to config will throw an informative error, which is beneficial for JavaScript users. The accompanying test changes are also correct, using @ts-expect-error to acknowledge the new compile-time error while still verifying the runtime error. The implementation is clever and effectively achieves the stated goal. The changes look good.

jhuleatt

I love this attention to detail to make config deprecation as clear as possible!

jhuleatt · 2025-10-30T13:48:13Z

src/v1/config.ts

      "Migration guide: https://firebase.google.com/docs/functions/config-env#migrate-config"
  );
-}
+}) as unknown as never;


What does adding in the as unknown do? I tried removing it in the TS playground and it doesn't seem to change anything

iiuc as unknown basically erases types before and I think I needed to do it to ultimately cast this type as never to prevent tsc from complaining. let me double check to confirm!

Confirmed that this isn't necessary. Great catch!

* BREAKING: Upgrade TypeScript to v5.9.3 (#1746) Upgrades from TypeScript v4.3.5 to v5.9.3. All tests pass successfully. * BREAKING: Drop Node.js 14/16 support, require Node.js >=18 (#1747) * BREAKING: Drop Node.js 14/16 support, require Node.js >=18 - Update package.json engines to require Node.js >=18.0.0 - Upgrade @types/node from v14 to v18 - Update TypeScript target from ES2019 to ES2022 - Add useDefineForClassFields: false for backward compatibility - Update CI/CD workflows to test Node.js 18, 20, 22, and 24 - Set default CI/CD Node.js version to 24 - Update integration test documentation * BREAKING: remove functions.config() implementation (#1748) Replace functions.config() implementation with an error that provides clear migration guidance to the params module. This removes the deprecated API as planned for the next major release while helping developers migrate. The error message directs users to: https://firebase.google.com/docs/functions/config-env#migrate-config * chore: migrate to ESLint v9 and Flat Config (#1753) Upgraded eslint to v9 and replaced the legacy .eslintrc.js with the new eslint.config.js format. Applied minor fixes to 4 files (renaming unused catch variables to _e and one small refactor) to satisfy slightly stricter baseline rules from updated plugins. Mostly doing this due to our upgrade in TS to latest v5 version which the old versions of eslint ts plugins no longer support. * chore: enable esModuleInterop (#1751) * feat: add async error handling to onRequest (#1755) BREAKING CHANGE: Unhandled errors in async onRequest handlers now immediately return a 500 Internal Server Error instead of hanging until timeout. This may affect clients relying on 504 Gateway Timeout for retry logic. * BREAKING: Break TS build that uses functions.config() (#1757) Type out `functions.config()` API. Use of `functions.config()` API should now cause a BUILD error at compile time. ```ts import * as functions from "firebase-functions"; import {onRequest} from "firebase-functions/https"; import * as logger from "firebase-functions/logger"; const cfg = functions.config() export const helloWorld = onRequest((request, response) => { logger.info("Hello logs!", cfg); response.send("Hello from Firebase!"); }); ``` ```bash $ npm run build > build > tsc src/index.ts:5:23 - error TS2349: This expression is not callable. Type 'never' has no call signatures. 5 const cfg = functions.config() ~~~~~~ Found 1 error in src/index.ts:5 ``` * Add Firebase Data Connect v2 support (#1727) * Add Firebase Data Connect v2 support * Export dataconnect * Fix export * Rename Extract to VarName, since Extract is a built in type * Include auth context in event payload * Stronger typing for data connect params * Fix formatting and address comments * Apply another suggestion * Add region and fix bug in which event.service, event.connector, event.operation gets populated * Remove locations/... segment * Address comments * Fix linter * feat: enable ESM support via dual-publishing (#1750) - Configure tsdown to build both CJS and ESM outputs. - Update package.json exports to support both 'require' and 'import'. - Fix type hygiene issues by using explicit 'export type'. - Update protos/update.sh to generate ESM version of compiledFirestore and fix its imports for Node.js compatibility. - Configure build aliases to handle relative paths to protos correctly in both CJS and ESM builds. - Add packaging integration test to CI. ~Note: I enabled `esModuleInterop` in tsconfig.release.json to support default imports from CommonJS modules (like cors), which is required for proper ESM interop. This caused some chain-effect that required updating several unit tests and source files to use default imports for other CJS dependencies (e.g., fs, nock, jsonwebtoken) to align with the new compiler configuration.~ Fixed in #1751. * lock down permission per GitHub alert. * update lint rule to enforce prettier rules. * chore: update CHANGELOG for v7.0.0 * format. --------- Co-authored-by: Lisa Jian <[email protected]>

BREAKING: Break TS build that uses functions.config()

dce72c6

github-project-automation bot added this to [Cloud] Extensions + Functions Oct 30, 2025

gemini-code-assist bot reviewed Oct 30, 2025

View reviewed changes

jhuleatt approved these changes Oct 30, 2025

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github-project-automation bot moved this to Approved [PR] in [Cloud] Extensions + Functions Oct 30, 2025

Simplify as never cast.

7d7a3bd

taeold merged commit 337b47d into next Oct 30, 2025
19 checks passed

github-project-automation bot moved this from Approved [PR] to Done in [Cloud] Extensions + Functions Oct 30, 2025

taeold deleted the deprecate-config-ts branch October 30, 2025 16:54

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BREAKING: Break TS build that uses functions.config() #1757

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taeold commented Oct 30, 2025 •

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taeold commented Oct 30, 2025 •

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