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Lab 3.2 use script to join hypervisor to cloud





Hi, on lab 3.2 i am getting an error when running the ./tools/disocver_hosts.sh command, here is the output below, any ideas?

An error has occurred:

Traceback (most recent call last):

  File "/opt/stack/nova/nova/cmd/manage.py", line 1863, in main

    ret = fn(*fn_args, **fn_kwargs)

  File "/opt/stack/nova/nova/cmd/manage.py", line 1583, in discover_hosts

    hosts = host_mapping_obj.discover_hosts(ctxt, cell_uuid, status_fn)

  File "/opt/stack/nova/nova/objects/host_mapping.py", line 206, in discover_hosts

    cell_mappings = objects.CellMappingList.get_all(ctxt)

  File "/usr/local/lib/python2.7/dist-packages/oslo_versionedobjects/base.py", line 184, in wrapper

    result = fn(cls, context, *args, **kwargs)

  File "/opt/stack/nova/nova/objects/cell_mapping.py", line 137, in get_all

    db_mappings = cls._get_all_from_db(context)

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 978, in wrapper

    with self._transaction_scope(context):

  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__

    return self.gen.next()

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 1028, in _transaction_scope

    context=context) as resource:

  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__

    return self.gen.next()

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 633, in _session

    bind=self.connection, mode=self.mode)

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 398, in _create_session


  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 484, in _start

    engine_args, maker_args)

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 506, in _setup_for_connection

    "No sql_connection parameter is established")

CantStartEngineError: No sql_connection parameter is established




  • serewicz
    serewicz Posts: 1,000


    The discover_hosts command was used when the an added hypervisor is not showing up after being added to the cluster. It was a bug, that may have been addressed.  Were you able to add the second node, and spin up an instance without this script?  As well, which node were you on when you ran the command, the devstack-cc or the compute-node?


  • Hamad Yousif


    I had the same issue but I realized that I was on compute-node when I ran the script. Once I returned to devstack-cc, everything went well.



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