dagger-helm/dagger.go

package daggerhelm

import (
	"context"
	"errors"
	"fmt"
	"log"
	"os"
	"path"
	"text/template"

	"dagger.io/dagger"
)

const CONTAINER_IMAGE = "docker.io/alpine/k8s:1.26.3"

func Compile(
	ctx context.Context,
	client *dagger.Client,
	chartPath string,
	valuesFilePath string,
) (*dagger.Directory, error) {

	chart := client.Host().Directory(chartPath)

	tmpdir := os.TempDir()
	tmpdir = path.Join(tmpdir, "helm-dagger")
	err := os.MkdirAll(tmpdir, 0755)
	if err != nil {
		return nil, fmt.Errorf("failed to create tmpdir: %v", err)
	}
	tmpvalues, err := os.CreateTemp(tmpdir, "")
	if err != nil {
		return nil, fmt.Errorf("could not create a tempdir. err: %v", err)
	}

	if _, err := os.Stat(valuesFilePath); errors.Is(err, os.ErrNotExist) {
		return nil, fmt.Errorf("the values file does not exist: %v", err)
	}

	contents, err := os.ReadFile(valuesFilePath)
	if err != nil {
		return nil, fmt.Errorf("failed to read values file: %v", err)
	}

	tmpl, err := template.New(valuesFilePath).Delims("[[", "]]").Parse(string(contents))
	if err != nil {
		return nil, fmt.Errorf("failed to build template for values.yaml, err: %v", err)
	}
	err = tmpl.Execute(tmpvalues, struct{}{})
	if err != nil {
		return nil, fmt.Errorf("failed to execute template. err: %v", err)
	}

	err = tmpvalues.Sync()
	if err != nil {
		return nil, fmt.Errorf("failed to write to tmpfile. err: %v", err)
	}

	files, err := os.ReadDir(tmpdir)
	if err != nil {
		return nil, fmt.Errorf("failed to read tmpdir. err: %v", err)
	}

	valuesFileDirPath := tmpdir
	valuesFileRelativePath := files[0].Name()
	log.Println(valuesFileRelativePath)
	valuesFile := client.Host().Directory(valuesFileDirPath).File(valuesFileRelativePath)

	helmoutput := client.Container().
		From(CONTAINER_IMAGE).
		WithWorkdir("/mnt").
		WithDirectory("chart", chart).
		WithFile("chart/values.yaml", valuesFile).
		WithWorkdir("/mnt/chart").
		WithExec([]string{"helm", "template", ".", "--output-dir", "/mnt/output"})
	if exitCode, err := helmoutput.ExitCode(ctx); err != nil || exitCode != 0 {
		return nil, fmt.Errorf("failed to render helm chart: %v", err)
	}

	return helmoutput.Directory("/mnt/output"), nil
}