Pier is an open-source self-hosted PaaS designed for deploying applications to private servers. The project aims to minimize resource consumption, targeting 20–40 MB of RAM usage for the main process, excluding Traefik. This contrasts with existing solutions like Coolify, which typically require between 750 MB and 1.2 GB of RAM.
The architecture relies on a single static binary written in Rust, avoiding external runtime dependencies. Configuration data is stored in a local SQLite database, eliminating the need for an external PostgreSQL instance. The frontend uses HTMX and Alpine.js to reduce JavaScript overhead, while templates and translations are embedded directly into the binary.
For multi-server setups, Pier utilizes a lightweight agent binary that handles Docker operations and reports metrics. The system manages cross-server database clusters by publishing ports in a specific range and configuring firewalls. Security is maintained by separating root-level update operations from the main panel, which runs with non-root privileges.
To handle resource-intensive builds, the platform integrates Railpack with BuildKit. Because compiling user code can require over 4 GB of RAM, the system limits parallel builds and enforces cache management policies. On hosts with less than 4 GB of RAM, the UI displays a warning to users.
