depot_deploy: graceful handling of missing content

This patch improves the error handling for the case where the depot
lacks the content of the to-be-deployed pkg. Instead of infinitely
reattempting to obtain blueprints for such content, the deploy tool
prints a single message.

repos/gems/src/app/depot_deploy/child.h

@@ -61,6 +61,11 @@ class Depot_deploy::Child : public List_model<Child>::Element
 		Binary_name _binary_name { };
 		Config_name _config_name { };
 
+		/*
+		 * Set if the depot query for the child's blueprint failed.
+		 */
+		bool _pkg_incomplete = false;
+
 		bool _configured() const
 		{
 			return _pkg_xml.constructed()
@@ -122,6 +127,9 @@ class Depot_deploy::Child : public List_model<Child>::Element
 
 			/* import new start node */
 			_start_xml.construct(_alloc, start_node);
+
+			/* reset error state, attempt to obtain the blueprint again */
+			_pkg_incomplete = false;
 		}
 
 		void apply_blueprint(Xml_node pkg)
@@ -144,9 +152,24 @@ class Depot_deploy::Child : public List_model<Child>::Element
 			_pkg_xml.construct(_alloc, pkg);
 		}
 
+		void mark_as_incomplete(Xml_node missing)
+		{
+			/* print error message only once */
+			if(_pkg_incomplete)
+				return;
+
+			Archive::Path const path = missing.attribute_value("path", Archive::Path());
+			if (path != _blueprint_pkg_path)
+				return;
+
+			error(path, " incomplete or missing");
+
+			_pkg_incomplete = true;
+		}
+
 		void gen_query(Xml_generator &xml) const
 		{
-			if (_configured())
+			if (_configured() || _pkg_incomplete)
 				return;
 
 			xml.node("blueprint", [&] () {

repos/gems/src/app/depot_deploy/main.cc

@@ -73,6 +73,10 @@ class Depot_deploy::Children
 			blueprint.for_each_sub_node("pkg", [&] (Xml_node pkg) {
 				_children.for_each([&] (Child &child) {
 					child.apply_blueprint(pkg); }); });
+
+			blueprint.for_each_sub_node("missing", [&] (Xml_node missing) {
+				_children.for_each([&] (Child &child) {
+					child.mark_as_incomplete(missing); }); });
 		}
 
 		void gen_start_nodes(Xml_generator &xml, Xml_node common)

repos/gems/src/app/depot_query/main.cc

@@ -273,8 +273,8 @@ struct Depot_query::Main
 					catch (Xml_generator::Buffer_exceeded) {
 						throw; /* handled by 'generate' */ }
 					catch (...) {
-						warning("could not obtain blueprint for '", pkg, "'");
-					}
+						xml.node("missing", [&] () {
+							xml.attribute("path", pkg); }); }
 				});
 			});
 		}