通过heat创建stack的代码流程分析heat stack-create
谭献
Heat-api发送RPC请求
Heat/api/openstack/v1/stacks.py
@util.policy_enforce
def create(self, req, body):
"""Create a new stack."""
data = InstantiationData(body)
args = self.prepare_args(data)
result = self.rpc_client.create_stack(
req.context,
data.stack_name(),
data.template(),
data.environment(),
data.files(),
args,
environment_files=data.environment_files())
formatted_stack = stacks_view.format_stack(
req,
{rpc_api.STACK_ID: result}
)
return {'stack': formatted_stack}
Heat/rpc/client.py
def create_stack(self, ctxt, stack_name, template, params, files,
args, environment_files=None):
"""Creates a new stack using the template provided.
Note that at this stage the template has already been fetched from the
heat-api process if using a template-url.
:param ctxt: RPC context.
:param stack_name: Name of the stack you want to create.
:param template: Template of stack you want to create.
:param params: Stack Input Params/Environment
:param files: files referenced from the environment.
:param args: Request parameters/args passed from API
:param environment_files: optional ordered list of environment file
names included in the files dict
:type environment_files: list or None
"""
return self._create_stack(ctxt, stack_name, template, params, files,
args, environment_files=environment_files)
def _create_stack(self, ctxt, stack_name, template, params, files,
args, environment_files=None,
owner_id=None, nested_depth=0, user_creds_id=None,
stack_user_project_id=None, parent_resource_name=None):
"""Internal interface for engine-to-engine communication via RPC.
Allows some additional options which should not be exposed to users via
the API:
:param owner_id: parent stack ID for nested stacks
:param nested_depth: nested depth for nested stacks
:param user_creds_id: user_creds record for nested stack
:param stack_user_project_id: stack user project for nested stack
:param parent_resource_name: the parent resource name
"""
return self.call(
ctxt, self.make_msg('create_stack', stack_name=stack_name,
template=template,
params=params, files=files,
environment_files=environment_files,
args=args, owner_id=owner_id,
nested_depth=nested_depth,
user_creds_id=user_creds_id,
stack_user_project_id=stack_user_project_id,
parent_resource_name=parent_resource_name),
version='1.23')
最终RPC请求由heat-engine接收，真正有来创建stack的操作是由stack.create()来完成的。
Heat/engine/service.py
def create_stack(self, cnxt, stack_name, template, params, files,
args, environment_files=None,
owner_id=None, nested_depth=0, user_creds_id=None,
stack_user_project_id=None, parent_resource_name=None):
"""Create a new stack using the template provided.
Note that at this stage the template has already been fetched from the
heat-api process if using a template-url.
:param cnxt: RPC context.
:param stack_name: Name of the stack you want to create.
:param template: Template of stack you want to create.
:param params: Stack Input Params
:param files: Files referenced from the template
:param args: Request parameters/args passed from API
:param environment_files: optional ordered list of environment file
names included in the files dict
:type environment_files: list or None
:param owner_id: parent stack ID for nested stacks, only expected when
called from another heat-engine (not a user option)
:param nested_depth: the nested depth for nested stacks, only expected
when called from another heat-engine
:param user_creds_id: the parent user_creds record for nested stacks
:param stack_user_project_id: the parent stack_user_project_id for
nested stacks
:param parent_resource_name: the parent resource name
"""
LOG.info(_LI('Creating stack %s'), stack_name)
# 创建一个新的porject,之所以会新建一个独立的project，
#而不是直接用发起创建stack操作的project
#应该是从权限控制角度考虑,通过新的project只能访问相关software_config资源.
#通过分析stack.create_stack_user_project_id，其实际上是就是调用了keystone
#client的相关接口创建了一个新project.
def _create_stack_user(stack):
if not stack.stack_user_project_id:
try:
stack.create_stack_user_project_id()
except exception.AuthorizationFailure as ex:
stack.state_set(stack.action, stack.FAILED,
six.text_type(ex))
def _stack_create(stack):
# Create/Adopt a stack, and create the periodic task if successful
if stack.adopt_stack_data:
stack.adopt()
elif stack.status != stack.FAILED:
# 真正做事情的地方，些处调用的是heat/engine/stack.py中的create函数。
stack.create()
if (stack.action in (stack.CREATE, stack.ADOPT)
and stack.status == stack.COMPLETE):
if self.stack_watch:
# Schedule a periodic watcher task for this stack
self.stack_watch.start_watch_task(stack.id, cnxt)
else:
LOG.info(_LI("Stack create failed, status %s"), stack.status)
convergence = cfg.CONF.convergence_engine
# 对heat 模板进行验证。
stack = self._parse_template_and_validate_stack(
cnxt, stack_name, template, params, files, environment_files,
args, owner_id, nested_depth, user_creds_id,
stack_user_project_id, convergence, parent_resource_name)
self.resource_enforcer.enforce_stack(stack)
#把stack的信息写入数据库。
stack_id = stack.store()
if cfg.CONF.reauthentication_auth_method == 'trusts':
stack = parser.Stack.load(
cnxt, stack_id=stack_id, use_stored_context=True)
# 创建一个新的user.
_create_stack_user(stack)
if convergence:
action = stack.CREATE
if stack.adopt_stack_data:
action = stack.ADOPT
stack.thread_group_mgr = self.thread_group_mgr
stack.converge_stack(template=stack.t, action=action)
else:
self.thread_group_mgr.start_with_lock(cnxt, stack, self.engine_id,
_stack_create, stack)
return dict(stack.identifier())
接下来看一下stack.create() heat/engine/stack.py
注意其中的TaskRunner这个类及其回调函数self.stack_task。
在heat中，TaskRunner被广泛使用，用创建诸如create, update, suspend等的操作。
TaskRunner的构造参数中定义了，这个Task将执行的函数，对stack所涉及的资源执行的action，即创建。
最后调度这个Task运行，运行的过程是执行self.stack_task函数
@profiler.trace('Stack.create', hide_args=False)
@reset_state_on_error
def create(self):
"""Create the stack and all of the resources."""
def rollback():
if not self.disable_rollback and self.state == (self.CREATE,
self.FAILED):
self.delete(action=self.ROLLBACK)
self._store_resources()
# 因为我们是调用heat stack-create，所以这里是self.stack_task;如果我们调用的是
# heat stack-update,那么此处应该是self.update_task.
# 对于stack的其它操作，如suspend,resume,snapshot等是self.stack_task.具体的可以
#看一下heat/engine/stack.py中的代码。
creator = scheduler.TaskRunner(
self.stack_task, action=self.CREATE,
reverse=False, post_func=rollback,
error_wait_time=cfg.CONF.error_wait_time)
#此处将调用TaskRunner中的__call__()方法。在此__call__()方法中，self.stack_task
# 将会被执行。
creator(timeout=self.timeout_secs())
TaskRunner这个类定义在了heat/engine/scheduler.py中。
Heat engine中比较重要的几个文件就是scheduler.py, service.py, stack.py, resource,py, stack_lock.py, update.py
Scheduler.py中的两个类比较重要：
TaskRunner: 对stack的任何操作， 最开始都是以TaskRunner来封装的。
DependencyTaskGroup: 一个Task中可能会有许多步骤(step)来完，实现task的循环执行主要依靠这个类
与wrappertask这个装饰器及配合yield来共同完成的。
Service.py中主要定义了三个类：
EngineService:
EngineListenerService:
ThreadGroupManager: 实现把对stack的操作放到子线程中执行。
这个stack_task有三个重要的点：
scheduler.wrappertask进行了装饰，意味这task需要处理subtask
scheduler.DependencyTaskGroup，构造该对象，即拓扑结构的图，该图上的每个节点都是一个资源，即资源上执行的task，即stack_task的子任务
yield action_task()，这是yield关键字的使用，有yield之后，函数就成为一个对象了，那么直接调用stack_task不会执行该函数，而是返回一个迭代器对象
下面来看stack_task()， 同时注意所用的装饰器。
@scheduler.wrappertask
def stack_task(self, action, reverse=False, post_func=None,
error_wait_time=None,
aggregate_exceptions=False, pre_completion_func=None):
"""A task to perform an action on the stack.
All of the resources are traversed in forward or reverse dependency
order.
:param action: action that should be executed with stack resources
:param reverse: define if action on the resources need to be executed
in reverse order (resources - first and then res dependencies )
:param post_func: function that need to be executed after
action complete on the stack
:param error_wait_time: time to wait before cancelling all execution
threads when an error occurred
:param aggregate_exceptions: define if exceptions should be aggregated
:param pre_completion_func: function that need to be executed right
before action completion. Uses stack ,action, status and reason as
input parameters
"""
LOG.debug("Jeffrey: stack.stack_task")
try:
lifecycle_plugin_utils.do_pre_ops(self.context, self,
None, action)
except Exception as e:
self.state_set(action, self.FAILED, e.args[0] if e.args else
'Failed stack pre-ops: %s' % six.text_type(e))
if callable(post_func):
post_func()
return
self.state_set(action, self.IN_PROGRESS,
'Stack %s started' % action)
stack_status = self.COMPLETE
reason = 'Stack %s completed successfully' % action
action_method = action.lower()
# If a local _$action_kwargs function exists, call it to get the
# action specific argument list, otherwise an empty arg list
handle_kwargs = getattr(self,
'_%s_kwargs' % action_method,
lambda x: {})
@functools.wraps(getattr(resource.Resource, action_method))
def resource_action(r):
# Find e.g resource.create and call it
handle = getattr(r, action_method)
LOG.debug("Jeffrey: stack.stack_task.resource_action: handle=%s" % handle)
#此处实际上就是调用了资源对应的handler函数，比如handle_create()
# 这些handle_Xxaction()函数在定义资源的时候已经实现，具体实例可以参看：
# heat/engine/resources/openstack/nova/server.py
return handle(**handle_kwargs(r))
action_task = scheduler.DependencyTaskGroup(
self.dependencies,
resource_action,
reverse,
error_wait_time=error_wait_time,
aggregate_exceptions=aggregate_exceptions)
try:
LOG.debug("Jeffrey: stack.stack_task.resource_action: action_task 1")
# 调用了DependcyTaskGroup的__call__()，在__call__中又调用了回调函数
# resource_action
yield action_task()
LOG.debug("Jeffrey: stack.stack_task.resource_action: action_task 1")
继续看scheduler.py中的__call__()
def __call__(self):
"""Return a co-routine which runs the task group."""
LOG.debug("Jeffrey: DependencyTaskGroup.__call__ : self._ready()=%s" % self._ready())
raised_exceptions = []
while any(six.itervalues(self._runners)):
try:
for k, r in self._ready():
LOG.debug("Jeffrey: DependencyTaskGroup.__call__.r=%s" % r)
r.start()
上面的r.start调用的是scheduler.py中的start():
这个函数主要是执行传递进来的Task，result = self._task(*self._args, **self._kwargs)不一定是去执行这个函数，就因为
yield关键字的存在导致其成为一个Generator对象了，所以下 一步有个类型判断，对于GeneratorType意味着需要一步步执行，
调用step函数。若没有yield关键字，一切正常如以往。step函数则调用与yield配合的next函数，最后在run_to_completion函数中，
循环的调用next函数，直至yield抛出StopIteration异常.注意，此处的self._task实际上是在heat/engine/stack.py中定义的stack_task()
def start(self, timeout=None):
"""Initialise the task and run its first step.
If a timeout is specified, any attempt to step the task after that
number of seconds has elapsed will result in a Timeout being
raised inside the task.
"""
assert self._runner is None, "Task already started"
assert not self._done, "Task already cancelled"
LOG.debug("Jeffrey: scheduler.TaskRunner.start")
LOG.debug('%s starting' % six.text_type(self))
if timeout is not None:
self._timeout = Timeout(self, timeout)
result = self._task(*self._args, **self._kwargs)
if isinstance(result, types.GeneratorType):
self._runner = result
self.step()
else:
self._runner = False
self._done = True
LOG.debug('%s done (not resumable)' % six.text_type(self))
def step(self):
"""Run another step of the task.
Return True if the task is complete; False otherwise.
"""
LOG.debug("Jeffrey: scheduler.TaskRunner.step: self.done()=%s" % self.done())
if not self.done():
assert self._runner is not None, "Task not started"
if self._timeout is not None and self._timeout.expired():
LOG.info(_LI('%s timed out'), six.text_type(self))
self._done = True
self._timeout.trigger(self._runner)
else:
LOG.debug('%s running' % six.text_type(self))
try:
LOG.debug("Jeffrey: scheduler.TaskRunner.step: next(self._runner)=%s" % next(self._runner))
next(self._runner)
except StopIteration:
self._done = True
LOG.debug('%s complete' % six.text_type(self))
return self._done
def run_to_completion(self, wait_time=1):
"""Run the task to completion.
The task will sleep for `wait_time` seconds between steps. To avoid
sleeping, pass `None` for `wait_time`.
"""
while not self.step():
self._sleep(wait_time)
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