Function Render

pkg/engine/engine.go:1580–1669

Render executes the rendering of templates based on the provided options. nolint:funlen,gocritic // funlen: 75-line linear dispatch over (Full ? FullConfigProcess : ApplyPatches) with per-branch cluster-meta hydration and per-mode serialisation; splitting either branch would scatter the shared Fail

(ctx context.Context, c *client.Client, opts Options)

//
//nolint:funlen,gocritic // funlen: 75-line linear dispatch over (Full ? FullConfigProcess : ApplyPatches) with per-branch cluster-meta hydration and per-mode serialisation; splitting either branch would scatter the shared FailIfMultiNodes/loadValues/SerializeConfiguration steps across helpers without simplifying control flow. hugeParam: Options is the package's public configuration carrier; passing by pointer would propagate across pkg/commands and external consumers.
func Render(ctx context.Context, c *client.Client, opts Options) ([]byte, error) {
	// Validate TalosVersion early so malformed values surface a user-friendly
	// error instead of an opaque "semverCompare: invalid semantic version" from
	// inside template rendering.
	if opts.TalosVersion != "" {
		_, err := config.ParseContractFromVersion(opts.TalosVersion)
		if err != nil {
			return nil, errors.Wrap(err, "invalid talos-version")
		}
	}

	// Gather facts and enable lookup options
	if !opts.Offline {
		cmdName := opts.CommandName
		if cmdName == "" {
			cmdName = cmdNameTalm
		}

		err := helpers.FailIfMultiNodes(ctx, cmdName)
		if err != nil {
			return nil, errors.Wrap(err, "checking node selector")
		}

		helmEngine.LookupFunc = newLookupFunction(ctx, c, cmdName, opts.TalosEndpoints)
	}

	// Require at least one template before loading and rendering the chart.
	// Rendering it first would be wasted (the output is discarded when no
	// template is selected) and, worse, the render fires live lookups whose
	// "connection refused" then masks the real problem: the operator forgot
	// --file / --template. Fail fast with the actionable error instead. This
	// runs after the online multi-node guard, which is a cheaper precondition
	// with no network I/O.
	if len(opts.TemplateFiles) == 0 {
		return nil, errors.New("templates are not set for the command: please use `--file` or `--template` flag")
	}

	chartPath, err := os.Getwd()
	if err != nil {
		return nil, errors.Wrap(err, "resolving working directory")
	}

	if opts.Root != "" {
		chartPath = opts.Root
	}

	chrt, err := loader.LoadDir(chartPath)
	if err != nil {
		return nil, errors.Wrapf(err, "loading chart from %q", chartPath)
	}

	values, err := loadValues(opts)
	if err != nil {
		return nil, err
	}

	rootValues := map[string]any{
		helmKeyValues:   mergeMaps(chrt.Values, values),