Add helm CLI wrapper

lib/gitlab/helm.rb

+module Gitlab
+  class Helm
+    Error = Class.new(StandardError)
+
+    attr_accessor :namespace
+    attr_accessor :logger
+
+    delegate :debug, :debug?, to: :logger, allow_nil: true
+
+    def initialize(namespace, kubeconfig, logger: nil)
+      self.namespace = namespace
+      self.logger = logger
+      @kubeconfig = kubeconfig
+    end
+
+    def init!
+      prepare_env do |env|
+        helm('init', '--upgrade', env: env)
+      end
+    end
+
+    def install_or_upgrade!(app_name, chart)
+      prepare_env do |env|
+        helm('init', '--client-only', env: env)
+        helm('upgrade', '--install', '--namespace', namespace, app_name, chart, env: env)
+      end
+    end
+
+    private
+
+    def prepare_env(*args, &blk)
+      Dir.mktmpdir(['helm', namespace]) do |tmpdir|
+        kubeconfig_path = File.join(tmpdir, 'kubeconfig')
+        env = {
+           'HELM_HOME' => File.join(tmpdir, 'helm'),
+           'TILLER_NAMESPACE' => namespace,
+           'KUBECONFIG' => kubeconfig_path
+        }
+
+        File.open(kubeconfig_path, 'w') { |c| c << YAML.dump(@kubeconfig) }
+
+        debug("HELM: Running in tmpdir #{tmpdir}")
+        yield(env) if block_given?
+      end
+    end
+
+    def helm(*args, env: {})
+      Open3.popen3(env, 'helm', *args) do |_, stdout, stderr, wait_thr|
+        exit_status = wait_thr.value
+
+        stdout.readlines.each { |l| debug("HELM: #{l.chomp}") } if debug?
+
+        raise Error, stderr.read.chomp unless exit_status.success?
+      end
+    end
+  end
+end

spec/lib/gitlab/helm_spec.rb

+# coding: utf-8
+require 'spec_helper'
+
+describe Gitlab::Helm do
+  let(:namespace) { 'rails-spec' }
+  let(:kubeconfig) {}
+  let(:logger) {}
+  subject { described_class.new(namespace, kubeconfig, logger: logger)}
+
+  def mock_helm_invocation(success:, error: '')
+    stderr = StringIO.new(error)
+    process_status = double('process_status')
+    wait_thr = double('wait_thread')
+
+    expect(Open3).to receive(:popen3).at_least(:once).and_yield(StringIO.new, StringIO.new, stderr, wait_thr)
+    expect(wait_thr).to receive(:value).at_least(:once).and_return(process_status)
+    expect(process_status).to receive(:success?).at_least(:once).and_return(success)
+  end
+
+  shared_examples 'invokes helm binary' do |method, args|
+    context 'when helm binary fails' do
+      let(:error_text) { 'Something went wrong' }
+
+      before do
+        mock_helm_invocation(success: false, error: error_text)
+      end
+
+      it 'throws exception' do
+        expect { subject.send(method, *args) }.to raise_exception(Gitlab::Helm::Error, error_text)
+      end
+    end
+
+    context 'when helm binary exit-code is 0' do
+      before do
+        mock_helm_invocation(success: true)
+      end
+
+      it "doesn't raise exceptions" do
+        expect { subject.send(method, *args) }.not_to raise_exception
+      end
+    end
+  end
+
+  it { is_expected.to delegate_method(:debug).to(:logger) }
+  it { is_expected.to delegate_method(:debug?).to(:logger) }
+
+  describe '#init!' do
+    it 'invokes helm init --upgrade' do
+      expect(subject).to receive(:helm).with('init', '--upgrade', env: instance_of(Hash))
+
+      subject.init!
+    end
+
+    it_should_behave_like 'invokes helm binary', :init!, []
+  end
+
+  describe '#install_or_upgrade!' do
+    let(:app_name) { 'app_name' }
+    let(:chart) { 'stable/a_chart' }
+
+    it 'invokes helm upgrade --install --namespace namespace app_name chart' do
+      expect(subject).to receive(:helm).with('init', '--client-only', env: instance_of(Hash)).ordered.once
+      expect(subject).to receive(:helm).with('upgrade', '--install', '--namespace', namespace, app_name, chart, env: instance_of(Hash)).ordered.once
+
+      subject.install_or_upgrade!(app_name, chart)
+    end
+
+    it_should_behave_like 'invokes helm binary', :install_or_upgrade!, %w[app_name chart]
+  end
+end