1 files changed, 58 insertions, 0 deletions
diff --git a/lib/gitlab/kubernetes/default_namespace.rb b/lib/gitlab/kubernetes/default_namespace.rb
new file mode 100644
index 00000000000..c95362b024b
--- /dev/null
+++ b/lib/gitlab/kubernetes/default_namespace.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Kubernetes
+    class DefaultNamespace
+      attr_reader :cluster, :project
+
+      delegate :platform_kubernetes, to: :cluster
+
+      ##
+      # Ideally we would just use an environment record here instead of
+      # passing a project and name/slug separately, but we need to be able
+      # to look up namespaces before the environment has been persisted.
+      def initialize(cluster, project:)
+        @cluster = cluster
+        @project = project
+      end
+
+      def from_environment_name(name)
+        from_environment_slug(generate_slug(name))
+      end
+
+      def from_environment_slug(slug)
+        default_platform_namespace(slug) || default_project_namespace(slug)
+      end
+
+      private
+
+      def default_platform_namespace(slug)
+        return unless platform_kubernetes&.namespace.present?
+
+        if cluster.managed? && cluster.namespace_per_environment?
+          "#{platform_kubernetes.namespace}-#{slug}"
+        else
+          platform_kubernetes.namespace
+        end
+      end
+
+      def default_project_namespace(slug)
+        namespace_slug = "#{project.path}-#{project.id}".downcase
+
+        if cluster.namespace_per_environment?
+          namespace_slug += "-#{slug}"
+        end
+
+        Gitlab::NamespaceSanitizer.sanitize(namespace_slug)
+      end
+
+      ##
+      # Environment slug can be predicted given an environment
+      # name, so even if the environment isn't persisted yet we
+      # still know what to look for.
+      def generate_slug(name)
+        Gitlab::Slug::Environment.new(name).generate
+      end
+    end
+  end
+end