feat: add prometheus metrics

[jiangbo721]

Summary

Added Prometheus monitoring, users can add corresponding indicators to grafana to monitor alarms.

Tip

Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[luckylhb90]

File "dify/api/core/app/task_pipeline/workflow_cycle_manage.py", line 740, in _workflow_time_it
username = self._user.email if isinstance(self._user, Account) else self._user.name
^^^^^^^^^^^^^^^^

sqlalchemy.orm.exc.DetachedInstanceError: Instance <Account at 0x1773d2dd0> is not bound to a Session; attribute refresh operation cannot proceed (Background on this error at: https://sqlalche.me/e/20/bhk3)

2024-12-20 12:03:05,583,583 WARNING [large_language_model.py:691] 42e8fe48a1 Callback MetricsCallback on_new_chunk failed with error 'NoneType' object has no attribute 'latency'

Well done, I just need it, I tested it, some bugs, can be fixed.

[jiangbo721]

File "dify/api/core/app/task_pipeline/workflow_cycle_manage.py", line 740, in _workflow_time_it username = self._user.email if isinstance(self._user, Account) else self._user.name ^^^^^^^^^^^^^^^^

sqlalchemy.orm.exc.DetachedInstanceError: Instance <Account at 0x1773d2dd0> is not bound to a Session; attribute refresh operation cannot proceed (Background on this error at: https://sqlalche.me/e/20/bhk3)

2024-12-20 12:03:05,583,583 WARNING [large_language_model.py:691] 42e8fe48a1 Callback MetricsCallback on_new_chunk failed with error 'NoneType' object has no attribute 'latency'

Well done, I just need it, I tested it, some bugs, can be fixed.

have a try