Which path should Electron use for writable files when asar is enabled in production?

Answer the Question First

When an Electron app is packaged with asar, the directory that __dirname resolves to is inside the .asar archive, which is a read‑only virtual file system. The only reliable writable location that works on all supported platforms (Windows, macOS, Linux) is the directory returned by app.getPath('userData'). Electron does not perform any automatic redirection of writes from bundled paths to a writable folder.

Why app.getPath('userData')?

• It is guaranteed to be outside the .asar archive.
• It follows the operating system’s standard for application data (e.g., %APPDATA% on Windows, ~/.config on Linux, ~/Library/Application Support on macOS).
• It is writable even in sandboxed builds, provided the sandbox entitlements allow it.

Typical Usage Pattern

const { app } = require('electron');
const path = require('path');

// Path for bundled assets (read‑only)
const assetPath = path.join(__dirname, 'assets');

// Path for user‑generated or persistent data (writable)
const userDataPath = app.getPath('userData');

// Example: writing a JSON file
const fs = require('fs');
const data = { foo: 'bar' };
fs.writeFileSync(path.join(userDataPath, 'state.json'), JSON.stringify(data));

Handling Special Cases

• Large binaries: If you need to ship large files that you intend to modify, mark them as asar.unpacked in your build config, but still write user data to userData.
• Sandboxed macOS builds: Ensure the sandbox entitlement com.apple.security.files.user-selected.read-write or a broader com.apple.security.files entitlement is present if you need write access outside userData.
• Cross‑platform consistency: Using app.getPath('userData') everywhere keeps the code path identical in development (where __dirname is writable) and production.

Verification Steps (Optional)

1. Run a packaged build with asar enabled and attempt to write to __dirname – you should see an error or silent failure.
2. Write the same file to app.getPath('userData') and confirm it appears in the expected location on Windows, macOS, and Linux.

Missing Diagnostic Detail

If you have a requirement to write directly to a file that is part of the bundle (e.g., a configuration file that must be modified after first run), consider whether that file should be moved to asar.unpacked or to userData. Let us know the specific use case so we can refine the recommendation.