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OPA C# SDK

[!IMPORTANT] The documentation for this SDK lives at https://docs.styra.com/sdk, with reference documentation available at https://styrainc.github.io/opa-csharp

You can use the Styra OPA SDK to connect to Open Policy Agent and Enterprise OPA deployments.

SDK Installation

Nuget

dotnet add package Styra.Opa

SDK Example Usage (high-level)

All the code examples that follow assume that the high-level SDK module has been imported, and that an OpaClient instance was created:

using Styra.Opa;


private string serverURL = "http://opa-host:8181";
private string path = "authz/allow";
private OpaClient opa;

opa = new OPAClient(serverURL);

var input = new Dictionary<string, object>() {
    { "user", "alice" },
    { "action", "read" },
    {"resource", "/finance/reports/fy2038_budget.csv"},
};

// (local variable) bool allowed
var allowed = await opa.check("authz/allow", input);
// (local variable) violations List<string>?
var violations = await opa.evaluate<List<string>>("authz/violations", input);

// Normal true/false cases...
if (allowed) {
    // ...
} else {
    Console.WriteLine("Violations: " + violations);
}

Input types

The check and evaluate methods are overloaded for most standard JSON types, which include the following variants for the input parameter:

Result Types

OpaClient.check

For the check method, the output type is always bool.

OpaClient.evaluate<T>

For the evaluate method, the output type is configurable using generics, as shown in the example below.

string path = "authz/accounts/max_limit";

double maxLimit
try {
    maxLimit = opa.evaluate<double?>(path, "example");
}
catch (OpaException) {
    maxLimit = 0.0f;
}

Nullable types are also allowed for output types, and if an error occurs during evaluation, a null result will be returned to the caller.

string path = "authz/accounts/max_limit";

double? maxLimit = opa.evaluate<double?>(path, "example");

If the selected return type <T> is possible to deserialize from the returned JSON, evaluate<T> will attempt to populate the variable with the value(s) present.

public struct AuthzStatus
{
    public AuthzStatus(bool allowed)
    {
        Allowed = allowed;
    }

    public double Allowed { get; }

    public override string ToString() => $"Application authorized: {Allowed}";
}

var input = new Dictionary<string, object>() {
    { "user", "alice" },
    { "action", "read" },
};

AuthzStatus status;
try {
    status = opa.evaluate<AuthzStatus>(path, input);
}
catch (OpaException) {
    status = new AuthzStatus(false);
}

[!NOTE] For low-level SDK usage, see the sections below.

OPA OpenAPI SDK (low-level)

Summary

For more information about the API: Enterprise OPA documentation

Table of Contents

• SDK Installation
• SDK Example Usage
• Available Resources and Operations
• Error Handling
• Server Selection
• Authentication

SDK Example Usage

Example 1

using Styra.Opa.OpenApi;
using Styra.Opa.OpenApi.Models.Requests;
using Styra.Opa.OpenApi.Models.Components;
using System.Collections.Generic;

var sdk = new OpaApiClient(bearerAuth: "<YOUR_BEARER_TOKEN_HERE>");

var res = await sdk.ExecuteDefaultPolicyWithInputAsync(
    input: Input.CreateNumber(
        4963.69D
    ),
    pretty: false,
    acceptEncoding: Styra.Opa.OpenApi.Models.Components.GzipAcceptEncoding.Gzip
);

// handle response

Example 2

using Styra.Opa.OpenApi;
using Styra.Opa.OpenApi.Models.Requests;
using Styra.Opa.OpenApi.Models.Components;
using System.Collections.Generic;

var sdk = new OpaApiClient(bearerAuth: "<YOUR_BEARER_TOKEN_HERE>");

ExecutePolicyWithInputRequest req = new ExecutePolicyWithInputRequest() {
    Path = "app/rbac",
    RequestBody = new ExecutePolicyWithInputRequestBody() {
        Input = Input.CreateBoolean(
            false
        ),
    },
};

var res = await sdk.ExecutePolicyWithInputAsync(req);

// handle response

Example 3

using Styra.Opa.OpenApi;
using Styra.Opa.OpenApi.Models.Requests;
using Styra.Opa.OpenApi.Models.Components;
using System.Collections.Generic;

var sdk = new OpaApiClient(bearerAuth: "<YOUR_BEARER_TOKEN_HERE>");

ExecuteBatchPolicyWithInputRequest req = new ExecuteBatchPolicyWithInputRequest() {
    Path = "app/rbac",
    RequestBody = new ExecuteBatchPolicyWithInputRequestBody() {
        Inputs = new Dictionary<string, Input>() {
            { "key", Input.CreateStr(
                "<value>"
            ) },
        },
    },
};

var res = await sdk.ExecuteBatchPolicyWithInputAsync(req);

// handle response

Available Resources and Operations

OpaApiClient SDK

• ExecuteDefaultPolicyWithInput - Execute the default decision given an input
• ExecutePolicy - Execute a policy
• ExecutePolicyWithInput - Execute a policy given an input
• ExecuteBatchPolicyWithInput - Execute a policy given a batch of inputs
• Health - Verify the server is operational

Server Selection

Override Server URL Per-Client

The default server can also be overridden globally by passing a URL to the serverUrl: string optional parameter when initializing the SDK client instance. For example:

using Styra.Opa.OpenApi;
using Styra.Opa.OpenApi.Models.Requests;
using Styra.Opa.OpenApi.Models.Components;
using System.Collections.Generic;

var sdk = new OpaApiClient(
    serverUrl: "http://localhost:8181",
    bearerAuth: "<YOUR_BEARER_TOKEN_HERE>"
);

var res = await sdk.ExecuteDefaultPolicyWithInputAsync(
    input: Input.CreateNumber(
        4963.69D
    ),
    pretty: false,
    acceptEncoding: Styra.Opa.OpenApi.Models.Components.GzipAcceptEncoding.Gzip
);

// handle response

Error Handling

Handling errors in this SDK should largely match your expectations. All operations return a response object or throw an exception.

By default, an API error will raise a Styra.Opa.OpenApi.Models.Errors.SDKException exception, which has the following properties:

When custom error responses are specified for an operation, the SDK may also throw their associated exceptions. You can refer to respective Errors tables in SDK docs for more details on possible exception types for each operation. For example, the ExecuteDefaultPolicyWithInputAsync method throws the following exceptions:

Example

using Styra.Opa.OpenApi;
using Styra.Opa.OpenApi.Models.Requests;
using Styra.Opa.OpenApi.Models.Components;
using System.Collections.Generic;
using System;
using Styra.Opa.OpenApi.Models.Errors;

var sdk = new OpaApiClient(bearerAuth: "<YOUR_BEARER_TOKEN_HERE>");

try
{
    var res = await sdk.ExecuteDefaultPolicyWithInputAsync(
        input: Input.CreateNumber(
            4963.69D
        ),
        pretty: false,
        acceptEncoding: Styra.Opa.OpenApi.Models.Components.GzipAcceptEncoding.Gzip
    );

    // handle response
}
catch (Exception ex)
{
    if (ex is ClientError)
    {
        // Handle exception data
        throw;
    }
    else if (ex is Models.Errors.ServerError)
    {
        // Handle exception data
        throw;
    }
    else if (ex is Styra.Opa.OpenApi.Models.Errors.SDKException)
    {
        // Handle default exception
        throw;
    }
}

Authentication

Per-Client Security Schemes

This SDK supports the following security scheme globally:

To authenticate with the API the BearerAuth parameter must be set when initializing the SDK client instance. For example:

using Styra.Opa.OpenApi;
using Styra.Opa.OpenApi.Models.Requests;
using Styra.Opa.OpenApi.Models.Components;
using System.Collections.Generic;

var sdk = new OpaApiClient(bearerAuth: "<YOUR_BEARER_TOKEN_HERE>");

var res = await sdk.ExecuteDefaultPolicyWithInputAsync(
    input: Input.CreateNumber(
        4963.69D
    ),
    pretty: false,
    acceptEncoding: Styra.Opa.OpenApi.Models.Components.GzipAcceptEncoding.Gzip
);

// handle response

Community

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