Embed Helm chart templates in CLI

[ndhanushkodi]

Changes proposed in this PR:

• Make the helm charts directory a go module where the helm chart files are embedded into an exported variable
• Import the variable into the CLI to embed it at compilation time. The replace directive makes it so that you don't need to bump the dependency on changes to the charts files.
• New functions to read those local templates and load the install from there

How I've tested this PR:

• unit tests and ran CLI smoke tests (CLI smoke tests #743) with this binary

How I expect reviewers to test this PR:

• review

Checklist:

• Tests added
• CHANGELOG entry added

  HashiCorp engineers only, community PRs should not add a changelog entry.
  Entries should use present tense (e.g. Add support for...)

[t-eckert]

You could wrap this behavior in a separate function to reduce code duplication.

func readChart(chartDirName, fileName) (*chartFile, error) {
        bytes, err = chart.ReadFile(fmt.Sprintf("%s/%s", chartDirName, fileName))
	if err != nil {
		return nil, err
	}
	return &loader.BufferedFile{
		Name: fileName,
		Data: bytes,
	}
}

[lkysow]

I took a stab at a fun refactor using Thomas's suggestion and using filepath.Rel to do the removal of charts/:

func ReadChartFiles(chart embed.FS, chartDirName string) ([]*loader.BufferedFile, error) {
	var chartFiles []*loader.BufferedFile

	// Load Chart.yaml and values.yaml first.
	for _, f := range []string{chartFileName, valuesFileName} {
		buffered, err := readFile(chart, filepath.Join(chartDirName, f), chartDirName)
		if err != nil {
			return nil, err
		}
		chartFiles = append(chartFiles, buffered)
	}

	// Now load everything under templates/.
	dirs, err := chart.ReadDir(filepath.Join(chartDirName, templatesDirName))
	if err != nil {
		return nil, err
	}
	for _, dir := range dirs {
		if dir.IsDir() {
			// We only need to package up files.
			continue
		}

		buffered, err := readFile(chart, filepath.Join(chartDirName, templatesDirName, dir.Name()), chartDirName)
		if err != nil {
			return nil, err
		}
		chartFiles = append(chartFiles, buffered)
	}

	return chartFiles, nil
}

func readFile(chart embed.FS, f string, basePath string) (*loader.BufferedFile, error) {
	bytes, err := chart.ReadFile(f)
	if err != nil {
		return nil, err
	}
	rel, err := filepath.Rel(basePath, f)
	if err != nil {
		return nil, err
	}
	return &loader.BufferedFile{
		Name: rel,
		Data: bytes,
	}, nil
}

[lkysow]

Could definitely be cleaned up but might be a nice change.

[ndhanushkodi]

Great suggestion @t-eckert and thanks for giving it a shot Luke, it pretty much looks good to me that way. I ended up only changing a few variable names from what it looks like here

[t-eckert]

This looks great! I had some stylistic nits, but nothing major. You are doing great with this!

[lkysow]

Nice work!

For future selves: Nitya and I discussed instead of doing this, pinning the chart version that helm downloads using version/version.go. This would reduce the complexity here but this work has the nice effect that there are no external calls to Helm/repositories and that everything is packaged up in the compiled binary so based on that we decided to continue with this approach.

[lkysow]

I took a stab at a fun refactor using Thomas's suggestion and using filepath.Rel to do the removal of charts/:

func ReadChartFiles(chart embed.FS, chartDirName string) ([]*loader.BufferedFile, error) {
	var chartFiles []*loader.BufferedFile

	// Load Chart.yaml and values.yaml first.
	for _, f := range []string{chartFileName, valuesFileName} {
		buffered, err := readFile(chart, filepath.Join(chartDirName, f), chartDirName)
		if err != nil {
			return nil, err
		}
		chartFiles = append(chartFiles, buffered)
	}

	// Now load everything under templates/.
	dirs, err := chart.ReadDir(filepath.Join(chartDirName, templatesDirName))
	if err != nil {
		return nil, err
	}
	for _, dir := range dirs {
		if dir.IsDir() {
			// We only need to package up files.
			continue
		}

		buffered, err := readFile(chart, filepath.Join(chartDirName, templatesDirName, dir.Name()), chartDirName)
		if err != nil {
			return nil, err
		}
		chartFiles = append(chartFiles, buffered)
	}

	return chartFiles, nil
}

func readFile(chart embed.FS, f string, basePath string) (*loader.BufferedFile, error) {
	bytes, err := chart.ReadFile(f)
	if err != nil {
		return nil, err
	}
	rel, err := filepath.Rel(basePath, f)
	if err != nil {
		return nil, err
	}
	return &loader.BufferedFile{
		Name: rel,
		Data: bytes,
	}, nil
}

[lkysow]

Could definitely be cleaned up but might be a nice change.

[lkysow]

🎉 super cool!