Complete procedures with a way back.

Build Apache, MariaDB, PHP-FPM, TLS, application identity, database credentials, health checks, and backups as one verified stack.

Build nginx, MariaDB, PHP-FPM, TLS, isolated application paths, FastCGI safety rules, health checks, and backups.

Separate Unix identity, socket, resource limits, logs, environment, and health checks for an application instead of sharing the default pool.

Measure the current unit, add compatible filesystem and privilege restrictions, validate application paths, and roll out hardening without breaking package upgrades.

Separate CLI and FPM settings, hide unsafe disclosure, bound resources, secure sessions, centralize errors, and verify effective values through the web SAPI.

Install versioned runtimes, create distinct sockets and services, route each server block explicitly, and upgrade one application at a time.

Measure script inventory, size OPcache deliberately, choose a deployment invalidation strategy, enable observability, and prove cache health.

Align PHP, FPM, nginx or Apache, reverse-proxy, temporary storage, and application limits; then test accepted and rejected uploads.

Enable EPEL, CRB or CodeReady Builder, and the official Remi repository; switch the system PHP module to 8.5; install FPM and verify the exact runtime.

Keep the distribution PHP unchanged while adding Remi's php85 Software Collection, its FPM service, isolated configuration, and an explicit application handler.