Comment 5 for bug 1715463

Reviewed: https://review.openstack.org/501359
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=0b4a021e4224981e83dca67e7519458f9939f3cd
Submitter: Zuul
Branch: master

commit 0b4a021e4224981e83dca67e7519458f9939f3cd
Author: Erik Berg <email address hidden>
Date: Wed Sep 6 18:38:29 2017 +0000

    Fix binary name

    Before an upgrade, we have these type of entries in the db.

    MariaDB [nova]> SELECT id, host, `binary`, deleted, version FROM services;
    +----+--------------+--------------------+---------+---------+
    | id | host | binary | deleted | version |
    +----+--------------+--------------------+---------+---------+
    | 5 | r1-n-os-api | nova-osapi_compute | 0 | 16 |
    | 21 | r1-n-m-api | nova-metadata | 0 | 16 |

    The wsgi files we run basically boil down to something like

      NAME=metadata
      return wsgi_app.init_application(NAME)

    In the wsgi_app.py we see this function

      service_ref = objects.Service.get_by_host_and_binary(ctxt, host, name)

    Which results in a really big query, which again comes down to

      SELECT host, `binary` FROM services
        WHERE host = 'r1-n-m-api' AND `binary` == 'metadata'

    No results. service_ref is set to None. Carry on.

      if service_ref:
        #Nope.
      else:
        try:
          ...
          service_obj.host = host
          service_obj.binary = 'nova-%s' % name
          service_obj.create()

    Which results in a INSERT statement something like this;

      INSERT INTO services(host, `binary`, report_count, disabled, deleted, version)
        VALUES ('r1-n-m-api', 'nova-metadata', 0, 0, 0, 22)

      ERROR 1062 (23000): Duplicate entry 'r1-n-m-api-nova-metadata-0' for key 'uniq_services0host0binary0deleted'

    So the first suggested fix is to prepend 'nova-' to the name, and make both
    queries ask for 'nova-metadata'. There's also a check that it doesn't start
    with 'nova-', incase someone decides to prepend 'nova-' to the NAME= in the
    wsgi-file. Which migth be a litte overkill, but just a safeguard none the less.

    Change-Id: I58cf9a0115a98c78e5d2fb57c41c13ba6fac0fad
    Closes-bug: 1715463