What is flate?

Flux is a system for managing server infrastructure by storing configuration files in a Git repository and automatically applying them to a running cluster of servers. Engineers write files describing what software should run and how, and Flux keeps the live system in sync with those files. Working with a Flux repository normally requires several separate command-line tools installed and a live cluster to connect to. Flate is a command-line tool that lets you render, inspect, and compare Flux configuration files without any of that. It ships as a single binary: you download one file and it works. It does not need a running cluster, does not call out to external tools like kubectl or helm, and does not require a network connection once installed. All the underlying libraries for template rendering and package management are compiled directly into the binary. The tool has four main operations. Get lists the configuration groups and packaged software components in a repository. Build renders them into full configuration output. Diff compares two versions of the repository, which is particularly useful when reviewing a code change. Test runs validation checks on every resource and reports pass, fail, or skipped, similar to how a code test suite would behave. A notable feature is changed-only mode. When you provide a second path representing a baseline version of the repository, flate identifies which parts of the configuration actually changed and processes only those parts. This makes it much faster for large repositories where a single code change might touch only a small corner of the configuration tree. On real-world repositories, single-file diffs can complete in tens of milliseconds. Flate is a Go rewrite of a Python tool called flux-local and is intended for use in automated CI pipelines where speed and minimal dependencies matter. It is written in Go.