3593: Another round of hardening Workbench's render_exception.

render_exception was counting on session[:user] to help render the
error page.  We recently excised that, which is turning exceptions
into 500s.  This commit restores the session user object, but uses it
only for error rendering, in keeping with the spirit of the previous
revert.  This commit also defends against more possible failure cases
in render_exception, and adds a basic test for it.

diff --git a/apps/workbench/app/controllers/application_controller.rb b/apps/workbench/app/controllers/application_controller.rb
index 222888085d9e3bb95973f2a2865c3efbb569b7f5..bbc2a825ba1d4e32681e1930619fd90a598c59e8 100644 (file)
--- a/apps/workbench/app/controllers/application_controller.rb
+++ b/apps/workbench/app/controllers/application_controller.rb
@@ -62,22 +62,31 @@ class ApplicationController < ActionController::Base
     else
       @errors = [e.to_s]
     end
-    # If the user has an active session, and the API server is available,
-    # make user information available on the error page.
+    # Make user information available on the error page, falling back to the
+    # session cache if the API server is unavailable.
     begin
       load_api_token(session[:arvados_api_token])
     rescue ArvadosApiClient::ApiError
-      load_api_token(nil)
+      unless session[:user].nil?
+        begin
+          Thread.current[:user] = User.new(session[:user])
+        rescue ArvadosApiClient::ApiError
+          # This can happen if User's columns are unavailable.  Nothing to do.
+        end
+      end
     end
-    # Preload projects trees for the template.  If that fails, set empty
+    # Preload projects trees for the template.  If that's not doable, set empty
     # trees so error page rendering can proceed.  (It's easier to rescue the
     # exception here than in a template.)
-    begin
-      build_project_trees
-    rescue ArvadosApiClient::ApiError
-      @my_project_tree ||= []
-      @shared_project_tree ||= []
+    unless current_user.nil?
+      begin
+        build_project_trees
+      rescue ArvadosApiClient::ApiError
+        # Fall back to the default-setting code later.
+      end
     end
+    @my_project_tree ||= []
+    @shared_project_tree ||= []
     render_error(err_opts)
   end
 
@@ -427,6 +436,15 @@ class ApplicationController < ActionController::Base
       false  # We may redirect to login, or not, based on the current action.
     else
       session[:arvados_api_token] = params[:api_token]
+      session[:user] = {
+        uuid: user.uuid,
+        email: user.email,
+        first_name: user.first_name,
+        last_name: user.last_name,
+        is_active: user.is_active,
+        is_admin: user.is_admin,
+        prefs: user.prefs
+      }
 
       if !request.format.json? and request.method.in? ['GET', 'HEAD']
         # Repeat this request with api_token in the (new) session

diff --git a/apps/workbench/test/functional/application_controller_test.rb b/apps/workbench/test/functional/application_controller_test.rb
index 50f990aa0bca1119c11aba9b60a5365fdd6f8811..c2828020bdca966400301c68b486b505a20c20ff 100644 (file)
--- a/apps/workbench/test/functional/application_controller_test.rb
+++ b/apps/workbench/test/functional/application_controller_test.rb
@@ -303,4 +303,22 @@ class ApplicationControllerTest < ActionController::TestCase
     get(:show, {id: "zzzzz-zzzzz-zzzzzzzzzzzzzzz"}, session_for(:admin))
     assert_response 404
   end
+
+  test "Workbench returns 4xx when API server is unreachable" do
+    # We're really testing ApplicationController's render_exception.
+    # Our primary concern is that it doesn't raise an error and
+    # return 500.
+    orig_api_server = Rails.configuration.arvados_v1_base
+    begin
+      # The URL should look valid in all respects, and avoid talking over a
+      # network.  100::/64 is the IPv6 discard prefix, so it's perfect.
+      Rails.configuration.arvados_v1_base = "https://[100::f]:1/"
+      @controller = NodesController.new
+      get(:index, {}, session_for(:active))
+      assert_includes(405..422, @response.code.to_i,
+                      "bad response code when API server is unreachable")
+    ensure
+      Rails.configuration.arvados_v1_base = orig_api_server
+    end
+  end
 end