Instruction file imported from renderbit-technologies/WordPress-GCP-VM-Setup (.github/instructions/root-bash.instructions.md). Copyright stays with the author.

Root Bash Script Guidelines

• Treat install.sh as a thin orchestrator for setup-swap.sh and setup-wp-nginx.sh. Keep deployment logic in the setup scripts unless orchestration behavior itself is changing.
• Keep the Bash deployment path aligned with the Ansible path when shared behavior changes, unless the task is explicitly Bash-only.
• Preserve the current script shape: root check first, set -euo pipefail, readable logging, and early failure on invalid conditions.
• Follow the shell conventions from CONTRIBUTING.md: #!/bin/bash or the existing shebang style, quoted expansions, uppercase exported/global variables, and lowercase local variables.
• Prefer small, idempotent shell changes. Re-running the scripts should remain safe for swap setup, package installation, credentials reuse, WordPress bootstrap, and service configuration.

Interface Compatibility

• Preserve documented environment variable names and meanings such as DOMAIN, USE_WWW, WP_DB, WP_DB_USER, WP_DB_PASS, WP_ADMIN_PASS, MYSQL_ROOT_PASS, LE_EMAIL, ENABLE_FAIL2BAN, CONT, SWAP_SIZE, and SKIP_CERTBOT.
• Keep interactive and non-interactive flows compatible. If a variable is part of the documented interface, do not silently repurpose it or change its default behavior without updating documentation and the test harness.
• Preserve the current credential reuse model through the stored credentials file rather than regenerating secrets on every rerun.
• When adding new script inputs, make them work in both prompt-driven and environment-variable-driven execution.

Script Structure

• Keep logging and error handling consistent with the existing helper functions in the setup scripts.
• Prefer extracting shell logic into small helper functions over growing long inline blocks.
• When changing service configuration, keep script-side verification and restart behavior targeted rather than restarting everything unconditionally.
• Keep external dependencies explicit. For CI-style and local validation without public DNS, continue supporting SKIP_CERTBOT=y instead of requiring live certificate issuance.

Validation Flow

• Lint root shell scripts with ShellCheck when available.
• Validate script changes using the bash harness documented in tests/bash/README.md.
• For CI-style validation without public DNS, use the existing hosted-runner path and keep Certbot skipped through SKIP_CERTBOT=y.

Key References

• See README.md for the documented non-interactive environment variables and deployment flow.
• See CONTRIBUTING.md for shell style and testing expectations.
• See tests/bash/README.md for validation commands and harness usage.
• See .github/copilot-instructions.md for repository-wide rules that still apply alongside this file.