open-policy-agent/swift-opa

Swift-OPA is a Swift package for evaluating Open Policy Agent IR Plans compiled from Rego policies.

The tool addresses the need to enforce policy decisions within Swift applications without external service calls. Rego is a declarative language designed for expressing authorization and other policies over structured data. Swift-OPA enables in-process evaluation by taking Rego policies, compiling them to an intermediate representation using the OPA build command with a plan target, and then evaluating those compiled plans directly within a Swift service or application. The package loads bundles from disk and executes queries against them, returning policy decisions as structured results.

Developers should choose this tool when they need to embed policy evaluation directly in a Swift application and want to avoid the latency and operational complexity of calling a remote OPA server. It suits projects where policies are known at build time and can be compiled ahead of time. The README notes that for use cases requiring metrics, logging, automatic bundle reloading over the network, and other management features, the Swift-OPA-SDK library provides a wrapper around this evaluator. The package offers optional traits to customize builds: the CLI trait can be disabled to drop the command-line tool and its dependencies, and the YAML trait can be disabled to exclude YAML builtin functions and their dependencies, allowing library-only consumers to minimize their dependency footprint.

The project maintains active engagement with reported issues, including documented limitations such as the inability to parse tar.gz files directly, requiring manual extraction before use. Development includes support for multiple optional features that can be independently toggled, indicating attention to flexibility and minimal dependency requirements for different use cases.