Package Kubenix script (#62)

* Package Kubenix script

* Update changelog

* Fix hardcoded kubeconfig

* Expose generated manifest with Kubenix CLI derivation passthru

pkgs/kubenix.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+
+set -uo pipefail
+
+function _help() {
+  echo "
+  kubenix - Kubernetes management with Nix
+
+  commands:
+    ""          - run diff, prompt for confirmation, then apply
+    apply       - create resources in target cluster
+    diff        - show a diff between configured and live resources
+    render      - print resource manifests to stdout
+
+  options:
+    -h --help   - show this menu
+  "
+}
+
+function _kubectl() {
+  vals eval -fail-on-missing-key-in-map <$MANIFEST | kubectl $@
+}
+
+# if no args given, add empty string
+[ $# -eq 0 ] && set -- ""
+
+# parse arguments
+while test $# -gt 0; do
+  case "$1" in
+
+  -h | --help)
+    _help
+    exit 0
+    ;;
+
+  "")
+    _kubectl diff -f - --prune
+    if [[ $? -eq 1 ]]; then
+      read -p 'apply? [y/N]: ' response
+      [[ $response == "y" ]] && _kubectl apply -f - --prune --all
+    fi
+    shift
+    ;;
+
+  render)
+    vals eval <$MANIFEST
+    shift
+    ;;
+
+  apply | diff)
+    _kubectl $@ -f - --prune
+    shift
+    ;;
+
+  *)
+    _kubectl $@
+    shift
+    ;;
+
+  esac
+done