Allow resuming from a failure during the "init" phase

This also shifts build failure transitions from individual functions
in utils.py to the init module handler.

module_build_service/models.py

@@ -265,6 +265,9 @@ class ModuleBuild(MBSBase):
             # If the rebuild_strategy isn't specified, use the default
             rebuild_strategy=rebuild_strategy or conf.rebuild_strategy
         )
+        # Add a state transition to "init"
+        mbt = ModuleBuildTrace(state_time=now, state=module.state)
+        module.module_builds_trace.append(mbt)
         session.add(module)
         session.commit()
         module_build_service.messaging.publish(

module_build_service/pdc.py

@@ -132,7 +132,7 @@ def get_variant_dict(data):
             result['active'] = data['active']
 
     if not result:
-        raise ValueError("Couldn't get variant_dict from %s" % data)
+        raise RuntimeError("Couldn't get variant_dict from %s" % data)
 
     return result
 

module_build_service/scheduler/handlers/modules.py

@@ -32,7 +32,7 @@ from module_build_service.utils import (
     attempt_to_reuse_all_components,
     record_component_builds,
     get_rpm_release_from_mmd)
-from module_build_service.errors import UnprocessableEntity
+from module_build_service.errors import UnprocessableEntity, Forbidden, ValidationError
 from module_build_service.builder.KojiContentGenerator import KojiContentGenerator
 
 from requests.exceptions import ConnectionError
@@ -139,8 +139,17 @@ def init(config, session, msg):
         record_component_builds(mmd, build, session=session)
         build.modulemd = mmd.dumps()
         build.transition(conf, models.BUILD_STATES["wait"])
-    except UnprocessableEntity:
-        build.transition(conf, models.BUILD_STATES["failed"])
+    # Catch custom exceptions that we can expose to the user
+    except (UnprocessableEntity, Forbidden, ValidationError, RuntimeError) as e:
+        # Rollback changes underway
+        session.rollback()
+        build.transition(conf, models.BUILD_STATES["failed"], state_reason=str(e))
+    except Exception as e:
+        log.exception(str(e))
+        # Rollback changes underway
+        session.rollback()
+        msg = "An unknown error occurred while validating the modulemd"
+        build.transition(conf, models.BUILD_STATES["failed"], state_reason=msg)
     finally:
         session.add(build)
         session.commit()

module_build_service/utils.py

@@ -843,14 +843,7 @@ def record_component_builds(mmd, module, initial_batch=1,
 
     # Format the modulemd by putting in defaults and replacing streams that
     # are branches with commit hashes
-    try:
-        format_mmd(mmd, module.scmurl, session=session)
-    except Exception as e:
-        module.transition(conf, models.BUILD_STATES["failed"],
-                          "Failed to validate modulemd file: %s" % str(e))
-        session.add(module)
-        session.commit()
-        raise
+    format_mmd(mmd, module.scmurl, session=session)
 
     # When main_mmd is set, merge the metadata from this mmd to main_mmd,
     # otherwise our current mmd is main_mmd.
@@ -865,10 +858,7 @@ def record_component_builds(mmd, module, initial_batch=1,
                 'conflicting components: {2}'
                 .format(mmd.name, main_mmd.name,
                         ', '.join(duplicate_components)))
-            module.transition(conf, models.BUILD_STATES["failed"], error_msg)
-            session.add(module)
-            session.commit()
-            raise RuntimeError(error_msg)
+            raise UnprocessableEntity(error_msg)
         merge_included_mmd(main_mmd, mmd)
     else:
         main_mmd = mmd
@@ -979,9 +969,15 @@ def submit_module_build(username, url, mmd, scm, optional_params=None):
                 component.state = None
                 db.session.add(component)
         module.username = username
-        module.transition(conf, models.BUILD_STATES["wait"],
-                          "Resubmitted by %s" % username)
-        module.batch = 0
+        # The last transition in the trace will be "failed", but we want to determine what the
+        # state was previous to the failure.
+        prev_state = module.module_builds_trace[-2].state
+        if prev_state == models.BUILD_STATES['init']:
+            transition_to = models.BUILD_STATES['init']
+        else:
+            transition_to = models.BUILD_STATES['wait']
+            module.batch = 0
+        module.transition(conf, transition_to, "Resubmitted by %s" % username)
         log.info("Resumed existing module build in previous state %s"
                  % module.state)
     else:

module_build_service/views.py

@@ -181,6 +181,9 @@ class ModuleBuildAPI(AbstractQueryableBuildAPI):
             log.error('Invalid JSON submitted')
             raise ValidationError('Invalid JSON submitted')
 
+        if module.state == models.BUILD_STATES['failed']:
+            raise Forbidden('You can\'t cancel a failed module')
+
         if r['state'] == 'failed' \
                 or r['state'] == str(models.BUILD_STATES['failed']):
             module.transition(conf, models.BUILD_STATES["failed"],