BREAKING: hide functions:config:* commands by default

[taeold]

We'll gate all mutating functions:config:* commands behind the new legacyRuntimeConfigCommands experiment. We'll keep functions:config:{get,export} available for inspection.

Includes some minor refactoring to align deprecation message across all surfaces.

$ firebase functions:config:set FOO=bar

Error: DEPRECATION NOTICE: Action required before March 2026

The functions.config() API and the Cloud Runtime Config service are deprecated. Deploys that rely on functions.config() will fail once Runtime Config shuts down in March 2026.

The legacy functions:config:* CLI commands are deprecated and will be removed before March 2026.

Migrate configuration to the Firebase Functions params APIs:

  import { defineJsonSecret } from "firebase-functions/params";

  const config = defineJsonSecret("RUNTIME_CONFIG");

  exports.myFunction = functions
    .runWith({ secrets: [config] })
    .https.onRequest((req, res) => {
      const apiKey = config.value().service.key;
      // ...
    });

To convert existing runtime config values, try the interactive migration command:

  firebase functions:config:export

Learn more: https://firebase.google.com/docs/functions/config-env#migrate-config

To run this legacy command temporarily, run the following command and try again:

  firebase experiments:enable legacyRuntimeConfigCommands

[gemini-code-assist]

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 new experiment flag, legacyRuntimeConfigCommands, to gate access to several functions:config:* commands, specifically those that modify configuration and the export command. This change is part of the ongoing deprecation of the functions.config() API and the underlying Cloud Runtime Config service, aiming to guide users towards newer Firebase Functions params APIs. The update also centralizes and refines the deprecation warning messages presented to users when interacting with these legacy features.

Highlights

• Command Gating: The mutating functions:config:* commands (clone, set, unset) and the functions:config:export command are now guarded by a new experiment flag, legacyRuntimeConfigCommands.
• Experiment Default State: The legacyRuntimeConfigCommands experiment is enabled by default, meaning the gated commands remain accessible unless the experiment is explicitly disabled. This behavior contradicts the pull request title's assertion of hiding commands by default.
• Deprecation Warning Centralization: The logic for logging functions.config() deprecation warnings has been centralized within src/functionsConfig.ts and updated with more comprehensive migration guidance for users.
• Experiment Renaming: The previous experiment flag dangerouslyAllowFunctionsConfig has been replaced by the new legacyRuntimeConfigCommands.
• functions:config:get Accessibility: The functions:config:get command remains fully accessible and does not require the legacyRuntimeConfigCommands experiment flag to be enabled.

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[gemini-code-assist]

Code Review

This pull request introduces a breaking change by hiding the functions:config:* commands behind the legacyRuntimeConfigCommands experiment, while keeping functions:config:{get,export} available. It also refactors the deprecation message for consistency. The review focuses on the correctness of the changes, particularly around the experiment flag and the deprecation warnings.