Altinn.Authorization.CommandLine.Azure.KeyVault 1.3.0

Altinn.Authorization.CommandLine

Altinn.Authorization.CommandLine is a small framework for building hosted command line applications. It combines System.CommandLine, Microsoft.Extensions.Hosting, dependency injection, and Spectre.Console-backed output behind a simple application builder.

Installation

Install the package with the .NET CLI:

dotnet add package Altinn.Authorization.CommandLine

Or with the NuGet Package Manager Console:

Install-Package Altinn.Authorization.CommandLine

Usage

Create a builder, register any application services, build the CliApplication, add commands, and run the application with the process arguments.

using Altinn.Authorization.CommandLine;
using Microsoft.Extensions.Logging;

var builder = CliApplication.CreateBuilder("Example command line application");
var cli = builder.Build();

cli.AddCommand("hello", "Writes a greeting", (
    [Argument] string name,
    ILogger<Program> logger) =>
{
    logger.LogInformation("Hello, {name}!", name);
});

return await cli.RunAsync(args);

Commands can also be implemented as handler types. The handler is constructed from the application service provider for each invocation and disposed after it runs.

using Altinn.Authorization.CommandLine;
using Altinn.Authorization.CommandLine.Results;
using Microsoft.Extensions.Logging;
using Spectre.Console;

var builder = CliApplication.CreateBuilder("Example command line application");
var cli = builder.Build();

cli.AddCommand<GreetCommand>("hello", "Writes a greeting");

return await cli.RunAsync(args);

internal sealed class GreetCommand(ILogger<GreetCommand> logger)
{
    public GreetingResult Invoke(
        [Option("--times", "-t")] int times = 5,
        [Argument] string message = "Hello, world!")
    {
        for (var i = 0; i < times; i++)
        {
            logger.LogInformation("Greeting: {message}", message);
        }

        return new GreetingResult(message);
    }
}

internal sealed class GreetingResult(string message)
    : ICommandResult
{
    public Task Execute(CommandInvocationContext context, CancellationToken cancellationToken = default)
    {
        context.Console.WriteLine(message);
        return Task.CompletedTask;
    }
}

Parameter Binding

Handler parameters are bound by the command handler factory:

• [Argument] binds a parameter from a command line argument.
• [Option] binds a parameter from a command line option. The default option name is --{parameterName}.
• CommandInvocationContext, CancellationToken, IConsole, ParseResult, and IServiceProvider are injected from the current invocation.
• Service parameters are resolved from dependency injection when the service provider reports that the parameter type is registered.
• Custom parameter attributes can implement IFromArgumentMetadata, IFromOptionMetadata, or IFromServiceMetadata for specialized binding.

Parameters with default values are treated as optional. Nullable parameters are also optional according to the parameter nullability metadata.

Use Microsoft.Extensions.Primitives.StringValues for whitespace-separated lists:

cli.AddCommand("deploy", "Deploy to environments", (
    [Option("--environments")] Microsoft.Extensions.Primitives.StringValues environments) =>
{
    foreach (var environment in environments)
    {
        Console.WriteLine(environment);
    }
});

--environments "test prod" and --environments test --environments prod both bind to two values. Each option occurrence consumes one token; an unquoted prod in --environments test prod remains a positional argument. Splitting handles spaces, tabs, and newlines, removes empty entries, and preserves order and duplicates. The same parsing applies to [Argument] StringValues parameters. Required lists reject empty or whitespace-only input; a parameter with = default is optional and binds to an empty list when omitted.

Return Values

Handlers can return:

• void, Task, or ValueTask.
• T, Task<T>, or ValueTask<T> when an ICommandResultHandlerResolver can resolve a handler for T.
• ICommandResult, which is executed directly.

An int result handler is registered by default and maps the returned value to the command return code.

Middleware

Commands expose a middleware pipeline through ICommandBuilder.Middleware.

cli.Middleware.Add(async (context, next, cancellationToken) =>
{
    var started = DateTimeOffset.UtcNow;
    await next(context, cancellationToken);
    var elapsed = DateTimeOffset.UtcNow - started;
    context.Console.MarkupLineInterpolated($"Completed in {elapsed.TotalMilliseconds:N0} ms");
});

Value parsing

Typed conversion uses ValueParser in Altinn.Authorization.CommandLine.Parsing. Arguments and options share this service, and it can also parse raw values without constructing a command. System.CommandLine handles tokenization, arity, and error presentation; conversion failures prevent handler invocation.

Built-in conversion supports strings, StringValues, IParsable<T> types, plain and annotated enums, nullable value types, arrays and common list interfaces, and filesystem types. A parameter default does not disable explicit-value parsing.

Configure ParsingOptions.AdditionalParsers to customize conversion. Each IValueParser exposes CanParse(Type) and a generic TryParse<T> method. Additional parsers run in list order before built-in conversion. A parser that claims a type reports invalid values through false and an error message; failures do not fall through to another parser.

ValueParsingContext exposes input values and delegation through TryParse<T>. Delegating the same type continues with the next parser. Delegating an inner type starts from the first parser, so nullable values and collection elements use the same configured conversions. ValueParser reads IOptionsMonitor<ParsingOptions> at each entry point and keeps that options instance during delegated parsing.

Environment-variable defaults

Options can fall back to an environment variable without handler code:

void Run([Option("--registry", DefaultFromEnvironment = "MY_OCI_REGISTRY")] string? registry = null)
{
    // registry is bound from the command line or the environment.
}

An explicit option wins over the environment variable; an unset, empty, or whitespace-only variable falls back to the parameter default. A required option without a parameter default requires either command-line input or an environment value. Environment values use the option's parser, including custom parsers such as StringValues whitespace splitting. Each variable supplies one token; ordinary string values retain spaces. Parse errors prevent invocation.

Factories accept a nullable DefaultValueProvider<T> for options and arguments. Use null when no default is configured, or DefaultValueProvider.FromValue(value) for a constant (including explicit null). Environment providers capture nonblank text during option resolution and defer conversion until the default is requested. For programmatic construction, pass the captured text and the parser resolved from DI:

var parser = services.GetRequiredService<ValueParser>();
var defaults = new EnvironmentValueDefaultValueProvider<string>(
    "MY_OCI_REGISTRY", registryText, parser);
var option = optionFactory.Create<string>(
    "--registry", [], "OCI registry", isRequired: true, defaults);

The non-generic DefaultValueProvider describes the provider's ValueType and color-aware help text. Bind<T>() validates compatibility during command construction and adapts compatible providers. Incompatible defaults fail before parsing. Only DefaultValueProvider<T> supplies values, through TryProvideValue; provision failures are command parse errors. An absent provider differs from a provider supplying an explicit null.

Environment help always displays [default: $NAME] instead of the captured value, even when the variable is unset. Parameter fallback values are not displayed in help; they still apply when the variable is unset, empty, or whitespace-only.

Contributing

Contributions to Altinn.Authorization.CommandLine are welcome. Open an issue for bugs or feature requests, or submit a pull request with the proposed changes.

License

Altinn.Authorization.CommandLine is licensed under the MIT License.