https://github.com/slok/go-helm-template
Simple go library to run Helm template without executing Helm
https://github.com/slok/go-helm-template
go golang helm helm-chart k8s kubernetes lib library template
Last synced: 3 months ago
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Simple go library to run Helm template without executing Helm
- Host: GitHub
- URL: https://github.com/slok/go-helm-template
- Owner: slok
- License: apache-2.0
- Created: 2022-01-23T09:31:41.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2025-03-14T07:47:11.000Z (3 months ago)
- Last Synced: 2025-03-19T08:39:20.734Z (3 months ago)
- Topics: go, golang, helm, helm-chart, k8s, kubernetes, lib, library, template
- Language: Go
- Homepage:
- Size: 391 KB
- Stars: 18
- Watchers: 2
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
- Codeowners: .github/CODEOWNERS
Awesome Lists containing this project
README
# go-helm-template
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[](https://raw.githubusercontent.com/slok/go-helm-template/master/LICENSE)
[](https://github.com/slok/go-helm-template/releases/latest)
Simple, fast and easy to use Go library to run [helm template][helm-template] without the need of a [Helm] binary nor its execution as an external command.
## Features
- Simple
- Fast
- Compatible with go [`fs.FS`](https://pkg.go.dev/io/fs#FS) (Template charts from FS, embedded, memory...)
- Testable.
- No Helm binary required.
- No external command execution from Go.
- Template specific files option.
## Getting started
```golang
package main
import (
"context"
"fmt"
"testing/fstest"
"github.com/slok/go-helm-template/helm"
)
// Chart data in memory.
const (
chart = `
apiVersion: v2
name: example-memory
version: 0.1.0
`
configmap = `
apiVersion: v1
kind: ConfigMap
metadata:
name: {{ printf "%s-%s" .Chart.Name .Release.Name | trunc 63 | trimSuffix "-" }}
namespace: {{ .Release.Namespace }}
labels:
{{- with .Values.labels -}}
{{ toYaml . | nindent 4 }}
{{- end }}
data:
something: something
`
)
func main() {
ctx := context.Background()
// Create chart in memory.
chartFS := make(fstest.MapFS)
chartFS["Chart.yaml"] = &fstest.MapFile{Data: []byte(chart)}
chartFS["templates/configmap.yaml"] = &fstest.MapFile{Data: []byte(configmap)}
// Load chart.
chart, err := helm.LoadChart(ctx, chartFS)
if err != nil {
panic(err)
}
// Execute helm template.
result, err := helm.Template(ctx, helm.TemplateConfig{
Chart: chart,
ReleaseName: "test",
Namespace: "no-kube-system",
Values: map[string]interface{}{
"labels": map[string]string{
"example-from": "go-helm-template",
},
},
})
if err != nil {
panic(err)
}
fmt.Println(result)
}
```
## Examples
- [Chart unit test](./examples/chart-unit-test): An example that shows how to use the library for chart unit testing.
- [Custom](examples/custom): An example that templates a chart with custom options (e.g CRDs).
- [Embed](examples/embed): An example that renders charts embedded in the binary using [`embed.FS`][embed-fs].
- [Memory](examples/memory): An example that templates a chart from memory.
- [Simple](examples/simple): A simple way of templating a chart in the FS.
## Tradeoffs
This library doesn't support anything apart from simple `helm template`. dependencies, hooks... and similar _fancy_ features, are not supported.
## Why
One of the [Helm]'s most powerful feature (if not the most) is its template system, lots of users only use [Helm] for this usage.
Not depending on helm as a system dependency, nor requiring to execute an external command, improves the portability and performance of applications that use Helm internally.
## Some use cases
- Remove process execution for simple helm template calls.
- Control better the execution flow of rendering multiple charts.
- Embed charts in compiled binaries with [`embed.FS`][embed-fs].
- Increase Helm template speed.
- Chart unit testing.
[helm]: https://helm.sh
[helm-template]: https://helm.sh/docs/helm/helm_template/
[embed-fs]: https://pkg.go.dev/embed#FS