OASert

OASert is a high-performance Rust library for runtime validation of HTTP requests against OpenAPI 3.x specifications. It provides a comprehensive suite of tools for traversing, validating, and caching OpenAPI document structures to ensure strict compliance with defined API contracts during request processing.

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Core Capabilities

• Comprehensive Request Validation
  Performs rigorous validation of HTTP request elements (payloads, headers, query parameters, path parameters) against OpenAPI v3.x specifications, ensuring complete compliance with defined schemas.

• High-Performance Validator Caching
  Implements a thread-safe, concurrent caching infrastructure powered by DashMap (v7.0) that minimizes redundant validator instantiations and optimizes memory usage.

• Advanced Specification Traversal
  Provides sophisticated algorithms for navigating complex OpenAPI documents, with robust handling of nested $ref references through pointer resolution and circular reference detection.

• Validation Error Reporting
  Detailed error reporting with specific categories like missing properties, invalid types, or unsupported schema versions.

• Supports OpenAPI Drafts
  Includes support for both OpenAPI 3.0.x (Draft 4) and OpenAPI 3.1.x (Draft 2020–12).

• Supports Partial Validation Allows for partial validation of requests (i.e. validate headers, validate scopes, validate body, etc.)

• Runtime Agnostic Does not depend on any specific runtime and can be dropped in where needed (i.e., hyper, aws lambda, etc.)

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Installation

Add OASert to your Cargo.toml:

[dependencies]
oasert = "0.1.1"

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Basic Usage

Initializing the Validator

1. Parse your OpenAPI specification into a serde_json::Value.
2. Create an OpenApiPayloadValidator using the parsed specification.
3. Pass incoming requests to the validator

See a full example using hyper here See a full example using AWS Lambda here

Components

1. ValidatorCache

Efficient caching mechanism for validators to avoid repeated instantiations.

• Insert or retrieve validators dynamically.
• Clear the cache when needed.
• Automatically create validators for specific IDs if not cached.

2. OpenApiTraverser

Utility class to traverse OpenAPI specifications with support for:

• Resolving $ref pointers.
• Fetching required or optional specification nodes.
• Handling complex paths and parameters.

3. OpenApiTypes

Type mapping utility to convert OpenAPI types (string, boolean, etc.) into native Rust types.

4. Error Handling

Comprehensive error handling for:

• Missing parameters or fields.
• Unsupported specification versions.
• Invalid schema values or types.