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https://github.com/phoban01/cue-flux-controller

A Kubernetes controller for CUE via Flux
https://github.com/phoban01/cue-flux-controller

controller cuelang flux fluxcd gitops gitops-toolkit kubernetes kubernetes-operator operator

Last synced: about 2 months ago
JSON representation

A Kubernetes controller for CUE via Flux

Host: GitHub
URL: https://github.com/phoban01/cue-flux-controller
Owner: phoban01
License: apache-2.0
Created: 2022-02-07T17:37:56.000Z (almost 3 years ago)
Default Branch: main
Last Pushed: 2023-11-22T10:55:09.000Z (about 1 year ago)
Last Synced: 2024-08-03T01:12:45.472Z (5 months ago)
Topics: controller, cuelang, flux, fluxcd, gitops, gitops-toolkit, kubernetes, kubernetes-operator, operator
Language: Go
Homepage:
Size: 474 KB
Stars: 69
Watchers: 6
Forks: 8
Open Issues: 1
Metadata Files:
- Readme: README.md
- License: LICENSE

Awesome Lists containing this project

awesome-cue - cue-flux-controller - A Kubernetes controller for CUE via Flux. (Projects)

README

# cue-controller

[![report](https://goreportcard.com/badge/github.com/phoban01/cue-flux-controller)](https://goreportcard.com/report/github.com/phoban01/cue-flux-controller)
[![license](https://img.shields.io/github/license/phoban01/cue-flux-controller.svg)](https://github.com/fluxcd/cue-flux-controller/blob/main/LICENSE)
[![release](https://img.shields.io/github/release/phoban01/cue-flux-controller/all.svg)](https://github.com/phoban01/cue-flux-controller/releases)

The cue-controller is an experimental Kubernetes controller for the CUE language. It integrates with Flux using the GitOps Toolkit and enables building GitOps pipelines directly in CUE.

The cue-controller is **heavily** based on the codebase for [kustomize-controller](https://github.com/fluxcd/kustomize-controller) and will aim for feature parity insofar as it makes sense to do so.

Use cases:
- GitOps Kubernetes resources using pure CUE, CUE+yaml or yaml alone
- Validate CUE or yaml with policies written in CUE
- Manage applications and infrastructure using modules & packages
- Single policy language to rule them all: write policy for local development, CI and last-mile in CUE

### Development Roadmap: Phase 1
- [x] Build CUE instances from a source repository
- [x] Specify the CUE working directory and module root
- [x] Specify the CUE expression(s) from which the instance will build
- [x] Set CUE tags and tag variables for the instance
- [x] Specify module root, package and directory variables for CUE instance
- [x] Apply manifests from a CUE instance
- [x] Impersonation via ServiceAccount
- [x] Remote cluster access via kubeconfig
- [x] Prune Kubernetes resources removed from the CUE source
- [x] Support for non-CUE files
- [x] Policy-mode (use CUE only for schema validation, with configurable failure modes)
- [x] Validation failure notifications (via notification controller)
- [x] Dependency ordering using `dependsOn`
- [x] Health checks for deployed workloads
- [x] Gate deployments using CUE expressions
- [ ] Support for decrypting secrets with Mozilla SOPS

Specifications:
* [API](docs/api/v1alpha1/cue.md)

For more on CUE visit: https://cuelang.org/
For more on Flux visit: https://fluxcd.io/

## Examples

Checkout https://github.com/phoban01/cuedemo for examples and patterns of using the cue-controller to build GitOps pipelines.

## Usage

The cue-controller requires that you already have the [GitOps toolkit](https://fluxcd.io/docs/components/)
controllers installed in your cluster. Visit [https://fluxcd.io/docs/get-started/](https://fluxcd.io/docs/get-started/) for information on getting started if you are new to `flux`.

### Installation

To install the latest release of the controller execute the following:
```bash
RELEASE=$(gh release list -R phoban01/cue-flux-controller -L 1 | awk '{print $1}')
RELEASE_MANIFESTS=https://github.com/phoban01/cue-flux-controller/releases/download/$RELEASE
kubectl apply -f "$RELEASE_MANIFESTS/cue-controller.crds.yaml"
kubectl apply -f "$RELEASE_MANIFESTS/cue-controller.rbac.yaml"
kubectl apply -f "$RELEASE_MANIFESTS/cue-controller.deployment.yaml"
```

This will install the cue-controller in the `flux-system` namespace.

### Usage
#### Define a Git repository source

Create a source object that points to a Git repository containing Kubernetes manifests and a Cue module:

```yaml
apiVersion: source.toolkit.fluxcd.io/v1beta1
kind: GitRepository
metadata:
name: cuedemo
namespace: default
spec:
interval: 5m
url: https://github.com/phoban01/cuedemo
ref:
branch: main
```

#### Define a CueInstance

Create a `CueInstance` resource that references the `GitRepository` source previously defined. The `CueInstance` specifies the module root and the expression we wish to build.

```yaml
apiVersion: cue.contrib.flux.io/v1alpha1
kind: CueInstance
metadata:
name: podinfo
namespace: default
spec:
interval: 5m
root: "./examples/podinfo"
expressions:
- out
tags:
- name: hpa
prune: true
sourceRef:
kind: GitRepository
name: cuedemo
```

Verify that the resources have been deployed:

```bash
kubectl -n default get sa,po,svc,hpa -l app=podinfo
```

Should return similar to the following:
```bash
NAME SECRETS AGE
serviceaccount/podinfo 1 10s

NAME READY STATUS RESTARTS AGE
pod/podinfo-59b967cb85-vd42l 1/1 Running 0 11s

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/podinfo ClusterIP 10.96.171.221 9898/TCP 5s

NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/podinfo Deployment/podinfo /500Mi, /75% 1 4 1 10s
```