Getting Started

Install nuget package

dotnet add package OpaDotNet.Wasm

Usage

To evaluate OPA policy you need to:

Add usings

using OpaDotNet.Wasm;

Load compiled policy

const string data = "{ \"world\": \"world\" }";

using var engine = OpaEvaluatorFactory.CreateFromWasm(
    File.OpenRead("data/policy.wasm")
    );

engine.SetDataFromRawJson(data);

Evaluate policy

IOpaEvaluator has several APIs for policy evaluation:

• EvaluatePredicate - Evaluates named policy with specified input. Response interpreted as simple true/false result.
• Evaluate - Evaluates named policy with specified input.
• EvaluateRaw - Evaluates named policy with specified raw JSON input.

var input = new { message = "world" };
var policyResult = engine.EvaluatePredicate(input);

Check the result

if (policyResult.Result)
{
    // We've been authorized.
}
else
{
    // Can't do that.
}

More samples here

Writing policy

See writing policy

Compiling policy

You have several options to compile rego policy into wasm module:

Consider example.rego file with the following policy:

package example

default hello = false

hello {
    x := input.message
    x == data.world
}

Manually

Either use the Compile REST API or opa build CLI tool.

For example, with OPA v0.20.5+:

opa build -t wasm -e example/hello example.rego

Which is compiling the example.rego policy file. The result will be an OPA bundle with the policy.wasm binary included. See samples for a more comprehensive example.

See opa build --help for more details.

With OpaDotNet.Compilation

You can use SDK to do compilation for you. For more information see OpaDotNet.Compilation.

OpaDotNet.Compilation.Cli

Important

You will need opa cli tool to be in your PATH or provide full path in RegoCliCompilerOptions.

dotnet add package OpaDotNet.Compilation.Cli

using OpaDotNet.Wasm;
using OpaDotNet.Compilation.Cli;

var compiler = new RegoCliCompiler();
var policyStream = await compiler.CompileFile("example.rego", new[] { "example/hello" });

// Use compiled policy.
using var engine = OpaEvaluatorFactory.CreateFromBundle(policyStream);

OpaDotNet.Compilation.Interop

dotnet add package OpaDotNet.Compilation.Interop

using OpaDotNet.Wasm;
using OpaDotNet.Compilation.Interop;

var compiler = new RegoInteropCompiler();
var policyStream = await compiler.CompileFile("example.rego", new[] { "example/hello" });

// Use compiled policy.
using var engine = OpaEvaluatorFactory.CreateFromBundle(policyStream);