nixhelm

This is a collection of helm charts in a nix-digestible format.

Background

A short overview for those unfamiliar with the tools involved.

• Kubernetes applications are described by YAML manifests: deployments, services, config maps and so on. A single application usually needs a lot of them.
• Helm is a package manager for Kubernetes. A chart is a set of templated manifests plus a values.yaml of settings, which Helm renders into the YAML applied to a cluster. Charts are published to chart repositories.
• Nix builds from pinned, hash-checked inputs, so a build produces the same result on any machine. helm repo update gives no such guarantee, it moves to whatever version the repository serves at that moment.
• nixhelm stores chart versions and hashes in charts/, which makes a chart a regular nix input. Pinning nixhelm pins every chart in use. Versions are refreshed nightly, so updates arrive as commits to pull rather than at deploy time.
• nixhelm itself only provides the charts. Rendering them into manifests is done by nix-kube-generators at build time, see Usage below.

Supported chart repositories

nixhelm supports both traditional HTTP helm chart repositories and OCI-compliant registries:

• HTTP/HTTPS repositories (ChartMuseum, traditional Helm repos)
• OCI registries (GitHub Container Registry, Docker Hub, Harbor, etc.)

If your chart is hosted in a git repo, remember that you can fetch it as a flake input and pass to buildHelmChart directly.

Outputs

The flake has the following outputs:

chartsMetadata.${repo}.${chart} contains the metadata about a specific chart.

chartsDerivations.${system}.${repo}.${chart} contains the derivations producing the charts.

charts { pkgs = ... }.${repo}.${chart} a shortcut for the above that doesn't depend on the nixpkgs input and allows to specify any nixpkgs.

The charts are updated nightly.

Usage

nix build .#chartsDerivations.x86_64-linux."argoproj"."argo-cd"

This will download the Argo CD helm chart to result/.

To build a chart, you should use the kube generators from github:farcaller/nix-kube-generators, and just pass your chart to the buildHelmChart function. So for example to render the Argo CD chart:

argo = (kubelib.buildHelmChart {
  name = "argo";
  chart = (nixhelm.charts { inherit pkgs; }).argoproj.argo-cd;
  namespace = "argo";
});

If you want to use this setup within Argo CD, check out cake.

Using the cache

This repository and all the charts within are publicly cached at cachix as nixhelm. Here's how you can quickly enable it in your nix installation.

Install cachix, either without flakes:

nix-env -iA cachix -f https://cachix.org/api/v1/install

or with flakes:

nix profile install nixpkgs#cachix

Then enable the cache:

cachix use nixhelm

Alternatively, manually add this to /etc/nix/nix.conf:

substituters = https://cache.nixos.org https://nixhelm.cachix.org
trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= nixhelm.cachix.org-1:esqauAsR4opRF0UsGrA6H3gD21OrzMnBBYvJXeddjtY=

Adding new charts

Clone the repository and run the following command from within it:

nix run .#helmupdater -- init $REPO $REPO_NAME/$CHART_NAME --commit

Where REPO is the URL to the chart repository, REPO_NAME is the short name for the repository and CHART_NAME is the name of the chart in the repository.

HTTP Repository Example

If you want to add prometheus:

nix run .#helmupdater -- init "https://prometheus-community.github.io/helm-charts" prometheus-community/prometheus --commit

OCI Registry Example

For charts hosted in OCI registries, use the oci:// scheme:

nix run .#helmupdater -- init "oci://ghcr.io/myorg/charts" myorg/nginx --commit

The command will create the properly formatted commit that you can then submit as a pull request to the repo.

License

Apache-2.0