Render a chart

Use this path for a preview endpoint, policy check, CI artifact, or GitOps generator. It reads chart inputs and returns text; it does not contact a Kubernetes cluster or create release history.

1. Install the renderer

dotnet add package HelmSharp.Chart --version 1.3.2
dotnet add package HelmSharp.Engine --version 1.3.2

The path passed to the loader must point at a chart directory containing Chart.yaml, or at a packaged chart archive.

2. Load values and render

Put the following in a console application's Program.cs, then pass the chart path as the first argument.

using HelmSharp.Chart;
using HelmSharp.Engine;

var chartPath = args.Length == 1
    ? args[0]
    : throw new ArgumentException("Pass the path to a Helm chart.");

var chart = await HelmChartLoader.LoadAsync(chartPath, CancellationToken.None);
var values = await HelmValues.BuildAsync(
    chart,
    valuesFiles: null,
    valuesContent: null,
    setValues: null,
    setFileValues: null,
    setStringValues: null,
    setJsonValues: null,
    cancellationToken: CancellationToken.None);

var renderer = new HelmTemplateRenderer(
    chart,
    releaseName: "demo",
    releaseNamespace: "default",
    values: values);

Console.WriteLine(renderer.Render());

The code has three deliberately separate stages:

1. HelmChartLoader reads Chart.yaml, templates, default values, chart files, CRDs, and packaged dependencies.
2. HelmValues.BuildAsync produces the dictionary exposed as .Values to templates.
3. HelmTemplateRenderer supplies release context and evaluates the templates. Render() returns manifests; RenderNotes() returns NOTES.txt separately when the caller needs it.

3. Add a values file or override

Supply one or more values files in order. A later file wins when both files set the same key.

var values = await HelmValues.BuildAsync(
    chart,
    valuesFiles: ["values.base.yaml", "values.production.yaml"],
    valuesContent: null,
    setValues: new Dictionary<string, string> { ["image.tag"] = "1.25.3" },
    setFileValues: null,
    setStringValues: null,
    setJsonValues: null,
    cancellationToken: cancellationToken);

Read Values and overrides before accepting these inputs from users. It explains precedence, string preservation, JSON values, and the difference between a file path and --set-file content.

4. Decide whether to move up a level

Stay on this API when the output belongs to your application. Move to HelmClient.TemplateAsync when a command-style CommandResult is easier for your interface, and to UpgradeInstallAsync only when the application is also responsible for applying the result.

If an existing chart renders differently from Helm, check the compatibility contract and the template-function matrix. Use HelmCompare to inspect a concrete difference.