Requirements

Requirements fail a pipeline before module execution when an environment prerequisite is not satisfied. Register built-in requirements through the Require factory:

builder.AddRequirement(Require.Windows());
builder.AddRequirement(Require.EnvironmentVariable("NUGET_API_KEY"));
builder.AddRequirement(Require.Ci("Publishing can only run in CI"));

The platform shortcuts are Require.Windows(), Require.Linux(), Require.MacOS(), and Require.WindowsAdmin(). Use Require.Platform(...) for another OSPlatform value.

Require.Ci() and Require.LocalEnvironment() use the same CI definition as the OnCI and OnLocal run conditions: IBuildSystemContext.IsCI is true when a known build system is detected, or otherwise when the CI environment variable is set to a value other than false or 0.

For custom asynchronous checks, implement IPipelineRequirement or derive from PipelineRequirement, whose EvaluateAsync is abstract. Evaluation receives the pipeline cancellation token:

public sealed class HasDotNetSdkRequirement : PipelineRequirement
{
    public override async Task<RequirementDecision> EvaluateAsync(
        IPipelineContext context,
        CancellationToken cancellationToken)
    {
        var result = await context.Shell.RunAsync(
            "dotnet",
            ["--version"],
            cancellationToken: cancellationToken);

        return result.ExitCode == 0
            ? RequirementDecision.Passed
            : RequirementDecision.Failed(".NET SDK is not installed");
    }
}

For synchronous checks, return a completed task from EvaluateAsync:

public sealed class Is64BitRequirement : PipelineRequirement
{
    public override Task<RequirementDecision> EvaluateAsync(
        IPipelineContext context,
        CancellationToken cancellationToken)
        => Task.FromResult(
            Environment.Is64BitProcess
                ? RequirementDecision.Passed
                : RequirementDecision.Failed("A 64-bit process is required"));
}

Requirements run in ascending Order (default 0). Every requirement is evaluated, and all failures are reported together in one RequirementNotMetException. A requirement that throws is reported as a failure too; its exception is available through InnerExceptions.

RequirementDecision.IsSatisfied reports the outcome. Construct decisions with Passed or Failed(reason); a bool can also convert implicitly. A bare string does not imply failure.

Requirements and run conditions receive IPipelineContext, giving them the same shared capability surface as global hooks. Use IModuleContext only inside modules.

Inspect the current environment

Use context.Environment.BuildSystem.IsCI for CI detection and .IsLocal for its inverse. For a specific provider, use .Is(BuildSystem.GitHubActions) or inspect .Current. Keep OnCI, OnLocal, Require.Ci(), and Require.LocalEnvironment() when declaring run conditions or requirements.