Build/test tools: copy the local environment configuration synchronously

[lancewillett]

Trac ticket: https://core.trac.wordpress.org/ticket/65716

Summary

On a fresh checkout, start.js begins copying .env.example asynchronously, then immediately loads .env. The read can finish first, leaving configuration values unset for that process.

This changes the initial copy to copyFileSync(), ensuring .env exists before dotenv.config() runs. Existing .env files remain untouched because COPYFILE_EXCL is preserved.

Branch behavior

The race is latent on trunk because the old-PHP authentication helper is no longer present.

On 6.9, missing LOCAL_DB_VERSION can make PHP 7.2 or 7.3 select --default-authentication-plugin=mysql_native_password. MySQL 8.4 removed this option and exits during startup.

This should be backported to 6.9 after landing on trunk.

Testing

• Confirmed a fresh trunk fixture copied and loaded .env before Docker startup.
• Reproduced the 6.9 delayed-copy path and wrong authentication option.
• Confirmed MySQL 8.4 rejects the removed option with exit code 1.
• Confirmed the patched 6.9 environment started with PHP 7.2 and healthy MySQL 8.4.
• Confirmed npm run env:install completed.

[github-actions]

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Props lancewillett, jonsurrell, lucasbustamante, mukesh27, adrianmoldovanwp.

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[Copilot]

Pull request overview

Ensures the local environment startup script reliably loads configuration on fresh checkouts by making the initial .env.example → .env creation step synchronous before dotenv.config() executes, avoiding a race that can leave env vars unset.

Changes:

• Replace async copyFile() with copyFileSync() for initial .env creation.
• Wrap the copy operation in a try/catch to preserve COPYFILE_EXCL behavior (do not overwrite existing .env).

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[sirreal]

This is good feedback. A better approach is probably to check whether the file already exists at the destination and copy if it doesn't, the try/catch should be safe to remove then, any errors that surface are useful information.

[github-actions]

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[Luc45]

Reviewing.

[Luc45]

Looks good. Fix is minimal and precise.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

tools/local-env/scripts/start.js:14

• The try/catch treats every copy failure as “.env already exists” and then continues. That can silently mask real problems (e.g. missing .env.example, permission errors), leaving the process running with an unexpected or empty configuration. Consider only swallowing the expected EEXIST error from COPYFILE_EXCL, and rethrow anything else.

try {
	copyFileSync( '.env.example', '.env', constants.COPYFILE_EXCL );
} catch ( e ) {
	console.log( '.env file already exists. .env.example was not copied.' );
}

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

tools/local-env/scripts/start.js:14

• The catch block currently treats any copyFileSync() failure as “.env already exists”. With COPYFILE_EXCL, EEXIST is expected when .env is present, but other errors (e.g. missing .env.example (ENOENT), permissions (EACCES), etc.) should be surfaced to avoid masking real setup problems. Consider only swallowing EEXIST and rethrowing other errors.

try {
	copyFileSync( '.env.example', '.env', constants.COPYFILE_EXCL );
} catch ( e ) {
	console.log( '.env file already exists. .env.example was not copied.' );
}