Add Kubernetes TlsSecret

Relates to https://gitlab.com/gitlab-org/gitlab/issues/33559

lib/gitlab/kubernetes/tls_secret.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Kubernetes
+    class TlsSecret
+      attr_reader :name, :cert, :key, :namespace_name
+
+      def initialize(name, cert, key, namespace_name)
+        @name = name
+        @cert = cert
+        @key = key
+        @namespace_name = namespace_name
+      end
+
+      def generate
+        ::Kubeclient::Resource.new(
+          type: tls_secret_type,
+          metadata: metadata,
+          data: data
+        )
+      end
+
+      private
+
+      def tls_secret_type
+        'kubernetes.io/tls'
+      end
+
+      def metadata
+        {
+          name: name,
+          namespace: namespace_name
+        }
+      end
+
+      def data
+        {
+          'tls.crt': Base64.strict_encode64(cert),
+          'tls.key': Base64.strict_encode64(key)
+        }
+      end
+    end
+  end
+end

spec/lib/gitlab/kubernetes/tls_secret_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Kubernetes::TlsSecret do
+  let(:secret) { described_class.new(name, cert, key, namespace) }
+  let(:name) { 'example-name' }
+  let(:cert) { 'example-cert' }
+  let(:key) { 'example-key' }
+  let(:namespace) { 'example-namespace' }
+
+  let(:data) do
+    {
+      'tls.crt': Base64.strict_encode64(cert),
+      'tls.key': Base64.strict_encode64(key)
+    }
+  end
+
+  describe '#generate' do
+    subject { secret.generate }
+
+    let(:resource) do
+      ::Kubeclient::Resource.new(
+        type: 'kubernetes.io/tls',
+        metadata: { name: name, namespace: namespace },
+        data: data
+      )
+    end
+
+    it { is_expected.to eq(resource) }
+  end
+end