$ show bottlerocket-os/bottlerocket
Bottlerocket is a free, open-source Linux-based operating system purpose-built for hosting containers. It is designed with a strong focus on security, immutability, and reliable updates. The system is configured entirely through an API-driven settings model, with all configuration stored as key-value pairs in a filesystem datastore. It supports multiple orchestrator variants (Amazon EKS, Amazon ECS, VMware, and bare metal) and cloud platforms (AWS, VMware, bare metal), with specialized variants for NVIDIA GPUs and FIPS compliance. The architecture is a minimal, Rust-heavy OS image built via a custom build system (Twoliter). The core components include a settings datastore with serialization/deserialization, a versioned migration framework for safe upgrades/downgrades, per-variant settings plugins loaded as dynamic libraries, and a TUF-based update mechanism with A/B partition flipping. The build system produces bootable images (AMIs, OVAs, raw images) and publishes them to TUF repositories. The codebase is organized as a Cargo workspace with hundreds of small crates, each handling a specific concern (migrations, defaults, plugins, models). Key entry points include the build system (cargo make), the settings datastore library (sources/api/datastore), the migration helpers (sources/api/migration/migration-helpers), and the per-variant settings defaults (sources/settings-defaults). The repository also contains tools for local VM testing, kernel config diffing, and secure boot key generation. While the codebase is well-structured and actively maintained, it suffers from significant duplication across many similar variants (e.g., Kubernetes 1.31 through 1.37) and a large number of archived migrations, which increases maintenance burden.
The LLM identified 4 files worth highlighting for reuse:
Implements a `Key` type for the settings datastore that supports dotted hierarchical keys with quoting for special characters. Provides parsing, segment manipulation, prefix stripping, and equality/hash based on canonical form. This is a well-crafted, self-contained component that could be reused in any key-value store requiring structured keys with escaping.
Provides a library of reusable migration implementations (AddSettingsMigration, RemoveSettingsMigration, ReplaceStringMigration, ReplaceListsMigration, RestrictListsMigration, etc.) that implement the `Migration` trait. These patterns solve the common problem of evolving a key-value configuration schema across versions, and can be extracted and applied to any similar datastore with minimal adaptation.
Defines a `RetryRead` trait that provides interruption-safe reading from files or other I/O sources. The implementation retries on EINTR and handles partial reads. This is a small, focused utility that solves a recurring systems programming problem and can be reused in any Rust project that needs robust file reading.
A standalone bash script that compares Linux kernel configurations across different Bottlerocket variants, architectures, or git commits. It extracts configs from built images or source trees and produces a structured diff. This is a reusable data engineering tool for anyone managing kernel configs across multiple builds, and demonstrates non-obvious shell scripting for config analysis.