feat: initial helm integration (thanks to @matejc)

helm2json was first implemented by matejc in
https://github.com/matejc/helm2json and incorperated in this project,
big thanks to @matejc for making this possible

default.nix

@@ -29,5 +29,6 @@ let
     k8s-submodules = ./k8s/submodule.nix;
     istio = ./istio;
     testing = ./testing;
+    helm = ./helm;
   };
 in kubenix

helm/chart2json.nix

@@ -0,0 +1,51 @@
+{ stdenvNoCC, lib, kubernetes-helm, gawk, remarshal, jq }:
+
+with lib;
+
+{
+  # chart to template
+  chart
+
+  # release name
+, name
+
+  # namespace to install release into
+, namespace ? null
+
+  # values to pass to chart
+, values ? {}
+
+  # kubernetes version to template chart for
+, kubeVersion ? null }: let
+  valuesJsonFile = builtins.toFile "${name}-values.json" (builtins.toJSON values);
+in stdenvNoCC.mkDerivation {
+  name = "${name}.json";
+  buildCommand = ''
+    # template helm file and write resources to yaml
+    helm template --name "${name}" \
+      ${optionalString (kubeVersion != null) "--kube-version ${kubeVersion}"} \
+      ${optionalString (namespace != null) "--namespace ${namespace}"} \
+      ${optionalString (values != {}) "-f ${valuesJsonFile}"} \
+      ${chart} >resources.yaml
+
+    # split multy yaml file into multiple files
+    awk 'BEGIN{i=1}{line[i++]=$0}END{j=1;n=0; while (j<i) {if (line[j] ~ /^---/) n++; else print line[j] >>"resource-"n".yaml"; j++}}' resources.yaml
+
+    # join multiple yaml files in jsonl file
+    for file in ./resource-*.yaml
+    do
+      remarshal -i $file -if yaml -of json >>resources.jsonl
+    done
+
+    # convert jsonl file to json array, remove null values and write to $out
+    cat resources.jsonl | jq -Scs 'walk(
+      if type == "object" then
+        with_entries(select(.value != null))
+      elif type == "array" then
+        map(select(. != null))
+      else
+        .
+      end)' > $out
+  '';
+  nativeBuildInputs = [ kubernetes-helm gawk remarshal jq ];
+}

helm/default.nix

@@ -0,0 +1,112 @@
+{ config, lib, pkgs, kubenix, ... }:
+
+with lib;
+
+let
+  cfg = config.kubernetes.helm;
+
+  globalConfig = config;
+
+  recursiveAttrs = mkOptionType {
+    name = "recursive-attrs";
+    description = "recursive attribute set";
+    check = isAttrs;
+    merge = loc: foldl' (res: def: recursiveUpdate res def.value) {};
+  };
+
+  parseApiVersion = apiVersion: let
+    splitted = splitString "/" apiVersion;
+  in {
+    group = if length splitted == 1 then "core" else head splitted;
+    version = last splitted;
+  };
+
+  chart2json = pkgs.callPackage ./chart2json.nix {  };
+  fetchhelm = pkgs.callPackage ./fetchhelm.nix {  };
+
+in {
+  imports = [
+    kubenix.k8s
+  ];
+
+  options.kubernetes.helm = {
+    instances = mkOption {
+      description = "Attribute set of helm instances";
+      type = types.attrsOf (types.submodule ({ config, name, ... }: {
+        options = {
+          name = mkOption {
+            description = "Helm release name";
+            type = types.str;
+            default = name;
+          };
+
+          chart = mkOption {
+            description = "Helm chart to use";
+            type = types.package;
+          };
+
+          namespace = mkOption {
+            description = "Namespace to install helm chart to";
+            type = types.nullOr types.str;
+            default = null;
+          };
+
+          values = mkOption {
+            description = "Values to pass to chart";
+            type = recursiveAttrs;
+            default = {};
+          };
+
+          kubeVersion = mkOption {
+            description = "Kubernetes version to build chart for";
+            type = types.str;
+            default = globalConfig.kubernetes.version;
+          };
+
+          overrides = mkOption {
+            description = "Overrides to apply to all chart resources";
+            type = types.listOf types.unspecified;
+            default = [];
+          };
+
+          overrideNamespace = mkOption {
+            description = "Whether to apply namespace override";
+            type = types.bool;
+            default = true;
+          };
+
+          objects = mkOption {
+            description = "Generated kubernetes objects";
+            type = types.listOf types.attrs;
+            default = [];
+          };
+        };
+
+        config.overrides = mkIf (config.overrideNamespace && config.namespace != null) [{
+          metadata.namespace = mkDefault config.namespace;
+        }];
+
+        config.objects = importJSON (chart2json {
+          inherit (config) chart name namespace values kubeVersion;
+        });
+      }));
+    };
+  };
+
+  # include helper helm methods as args
+  config._module.args.helm = {
+    fetch = fetchhelm;
+    chart2json = chart2json;
+  };
+
+  config.kubernetes.api = mkMerge (flatten (mapAttrsToList (_: instance:
+    map (object: let
+      apiVersion = parseApiVersion object.apiVersion;
+      name = object.metadata.name;
+    in {
+      "${apiVersion.group}"."${apiVersion.version}".${object.kind}."${name}" = mkMerge ([
+        object
+      ] ++ instance.overrides);
+    }) instance.objects
+  ) cfg.instances));
+}

helm/fetchhelm.nix

@@ -0,0 +1,48 @@
+{ stdenvNoCC, lib, kubernetes-helm, cacert }:
+
+let
+  cleanName = name: lib.replaceStrings ["/"] ["-"] name;
+
+in {
+  # name of the chart
+  chart
+
+  # chart url to fetch from custom location
+, chartUrl ? null
+
+  # version of the chart
+, version ? null
+
+# chart hash
+, sha256
+
+# whether to extract chart
+, untar ? true
+
+# use custom charts repo
+, repo ? null
+
+# pass --verify to helm chart
+, verify ? false
+
+# pass --devel to helm chart
+, devel ? false }: stdenvNoCC.mkDerivation {
+  name = "${cleanName chart}-${if version == null then "dev" else version}";
+
+  buildCommand = ''
+    export HOME="$PWD"
+    helm init --client-only >/dev/null
+    ${if repo == null then "" else "helm repo add repository ${repo}"}
+    helm fetch -d ./chart \
+      ${if untar then "--untar" else ""} \
+      ${if version == null then "" else "--version ${version}"} \
+      ${if devel then "--devel" else ""} \
+      ${if verify then "--verify" else ""} \
+      ${if chartUrl == null then (if repo == null then chart else "repository/${chart}") else chartUrl}
+    cp -r chart/*/ $out
+  '';
+  outputHashMode = "recursive";
+  outputHashAlgo = "sha256";
+  outputHash = sha256;
+  nativeBuildInputs = [ kubernetes-helm cacert ];
+}

helm/test.nix

@@ -0,0 +1,43 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+let
+  fetchhelm = pkgs.callPackage ./fetchhelm.nix {  };
+  chart2json = pkgs.callPackage ./chart2json.nix {  };
+in rec {
+  postgresql-chart = fetchhelm {
+    chart = "stable/postgresql";
+    version = "0.18.1";
+    sha256 = "1p3gfmaakxrqb4ncj6nclyfr5afv7xvcdw95c6qyazfg72h3zwjn";
+  };
+
+  istio-chart = fetchhelm {
+    chart = "istio";
+    version = "1.1.0";
+    repo = "https://storage.googleapis.com/istio-release/releases/1.1.0-rc.0/charts";
+    sha256 = "0ippv2914hwpsb3kkhk8d839dii5whgrhxjwhpb9vdwgji5s7yfl";
+  };
+
+  istio-official-chart = pkgs.fetchgit {
+    url = "https://github.com/fyery-chen/istio-helm";
+    rev = "47e235e775314daeb88a3a53689ed66c396ecd3f";
+    sha256 = "190sfyvhdskw6ijy8cprp6hxaazn7s7mg5ids4snshk1pfdg2q8h";
+  };
+
+  postgresql-json = chart2json {
+    name = "postgresql";
+    chart = postgresql-chart;
+    values = {
+      networkPolicy.enabled = true;
+    };
+  };
+
+  istio-json = chart2json {
+    name = "istio";
+    chart = istio-chart;
+  };
+
+  istio-official-json = chart2json {
+    name = "istio-official";
+    chart = "${istio-official-chart}/istio-official";
+  };
+}

tests/default.nix

@@ -32,6 +32,7 @@ let
           ./k8s/1.13/crd.nix
           ./k8s/submodule.nix
           ./k8s/defaults.nix
+          ./helm/simple.nix
           ./istio/bookinfo.nix
           ./submodules/simple.nix
           ./submodules/defaults.nix

tests/helm/simple.nix

@@ -0,0 +1,40 @@
+{ config, test, kubenix, k8s, helm, ... }:
+
+with k8s;
+
+let
+  corev1 = config.kubernetes.api.core.v1;
+  appsv1beta2 = config.kubernetes.api.apps.v1beta2;
+in {
+  imports = [
+    kubenix.helm
+  ];
+
+  test = {
+    name = "helm-simple";
+    description = "Simple k8s testing wheter name, apiVersion and kind are preset";
+    assertions = [{
+      message = "should have generated resources";
+      assertion =
+        appsv1beta2.StatefulSet ? "app-psql-postgreql" &&
+        corev1.ConfigMap ? "app-psql-postgresql-init-scripts" &&
+        corev1.Secret ? "app-psql-postgresql" &&
+        corev1.Service ? "app-psql-postgresql-headless" ;
+    } {
+      message = "should have namespace defined";
+      assertion =
+        appsv1beta2.StatefulSet.app-psql-postgresql.metadata.namespace == "test-namespace";
+    }];
+  };
+
+  kubernetes.api.namespaces.test-namespace = {};
+
+  kubernetes.helm.instances.app-psql = {
+    namespace = "test-namespace";
+    chart = helm.fetch {
+      chart = "stable/postgresql";
+      version = "3.0.0";
+      sha256 = "0icnnpcqvf1hqn7fc9niyifd0amlm9jfrx3iks0y360rk8wndbch";
+    };
+  };
+}