e2c89f777d
* Introduced new class Workflow that manages life-cycle of running workflows and is responsible for managing workflow persistent state * Moved all workflow level logic to workflow handler and Workflow class * Changed semantics if how workflows start errors are handled. Previously, in case of invalid user input Mistral engine would store information about error in "state_info" field of workflow execution and bubble up an exception to the user. This approach was incorrect for a number of reasons including broken semantics: if an exception was raised due to invalid input it's normal to expect that system state has not changed. After this refactoring, engine only raises an exception in case of bad user input. That way behavior is consistent with the idea of exceptional situations. * Fixed unit tests in according to the previous point * Fixed a number of logical issues in tests. For example, in test_default_engine.py we expected one type of errors (e.g. env not found) but effectively received another one (invalid input). Partially implements: blueprint mistral-engine-error-handling Change-Id: I09070411fd833df8284cb80db69b8401a40eb6fe
125 lines
3.4 KiB
Python
125 lines
3.4 KiB
Python
# Copyright 2016 - Nokia Networks.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from oslo_log import log as logging
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import traceback as tb
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from mistral.db.v2 import api as db_api
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from mistral.db.v2.sqlalchemy import models as db_models
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from mistral.engine import workflows
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from mistral import exceptions as exc
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from mistral.workflow import states
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LOG = logging.getLogger(__name__)
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def start_workflow(wf_identifier, wf_input, desc, params):
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wf = workflows.Workflow(
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db_api.get_workflow_definition(wf_identifier)
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)
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wf.start(wf_input, desc=desc, params=params)
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return wf.wf_ex
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def stop_workflow(wf_ex, state, msg=None):
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wf = workflows.Workflow(
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db_api.get_workflow_definition(wf_ex.workflow_id),
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wf_ex=wf_ex
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)
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# In this case we should not try to handle possible errors. Instead,
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# we need to let them pop up since the typical way of failing objects
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# doesn't work here. Failing a workflow is the same as stopping it
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# with ERROR state.
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wf.stop(state, msg)
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def fail_workflow(wf_ex, msg=None):
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stop_workflow(wf_ex, states.ERROR, msg)
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def on_task_complete(task_ex):
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wf_ex = task_ex.workflow_execution
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wf = workflows.Workflow(
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db_api.get_workflow_definition(wf_ex.workflow_id),
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wf_ex=wf_ex
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)
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try:
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wf.on_task_complete(task_ex)
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except exc.MistralException as e:
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msg = (
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"Failed to handle task completion [wf_ex=%s, task_ex=%s]: %s\n%s"
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% (wf_ex, task_ex, e, tb.format_exc())
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)
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LOG.error(msg)
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fail_workflow(wf.wf_ex, msg)
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def pause_workflow(wf_ex, msg=None):
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wf = workflows.Workflow(
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db_api.get_workflow_definition(wf_ex.workflow_id),
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wf_ex=wf_ex
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)
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wf.set_state(states.PAUSED, msg)
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def rerun_workflow(wf_ex, task_ex, reset=True, env=None):
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if wf_ex.state == states.PAUSED:
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return wf_ex.get_clone()
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wf = workflows.Workflow(
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db_api.get_workflow_definition(wf_ex.workflow_id),
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wf_ex=wf_ex
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)
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wf.rerun(task_ex, reset=reset, env=env)
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def resume_workflow(wf_ex, env=None):
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if not states.is_paused_or_idle(wf_ex.state):
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return wf_ex.get_clone()
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wf = workflows.Workflow(
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db_api.get_workflow_definition(wf_ex.workflow_id),
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wf_ex=wf_ex
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)
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wf.resume(env=env)
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def set_workflow_state(wf_ex, state, msg=None):
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if states.is_completed(state):
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stop_workflow(wf_ex, state, msg)
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elif states.is_paused(state):
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pause_workflow(wf_ex, msg)
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else:
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raise exc.MistralError(
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'Invalid workflow state [wf_ex=%s, state=%s]' % (wf_ex, state)
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)
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def lock_workflow_execution(wf_ex_id):
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# Locks a workflow execution using the db_api.acquire_lock function.
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# The method expires all session objects and returns the up-to-date
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# workflow execution from the DB.
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return db_api.acquire_lock(db_models.WorkflowExecution, wf_ex_id)
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