Reviewed:  https://review.opendev.org/699174
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=9a6766470ef127ee5495a5b74b7156bd5a80f03c
Submitter: Zuul
Branch:    stable/train

commit 9a6766470ef127ee5495a5b74b7156bd5a80f03c
Author: Bence Romsics <email address hidden>
Date:   Wed Nov 27 17:59:15 2019 +0100

    Locate RP-tree parent by hypervisor name
    
    Previously we assumed that we can look up the resource provider (created
    by nova) to be used as the parent of the agent and physical NIC resource
    provider tree by the name set in the config option DEFAULT.host. This
    assumption was wrong.
    
    While nova-compute's DEFAULT.host and neutron-agent's DEFAULT.host
    must match for port binding to work, the root resource provider created
    by nova does not belong to the compute host (where nova-compute runs)
    but it belongs to the compute nodes (i.e. hypervisors). Actually there
    may be multiple compute nodes managed by a single nova-compute (think
    of ironic). Plus the value of DEFAULT.host and the compute node's ID
    may be different even when nova-compute manages a hypervisor on the
    same host because of various deployment considerations. For example
    when tripleo does not manage the undercloud (so a libvirt hypervisor
    returns the plain hostname), but the same tripleo enforces it's host
    naming conventions in nova's and neutron's DEFAULT.host settings.
    
    This change enables neutron to use the hypervisor name to locate the
    root of the resource provider tree.
    
    We introduce a new configuration option for
    
    (1) ovs-agent: resource_provider_hypervisors, for example:
    
    [ovs]
    bridge_mappings = physnet0:br-physnet0,...
    resource_provider_bandwidths = br-physnet0:10000000:10000000,...
    resource_provider_hypervisors = br-physnet0:hypervisor0,...
    
    (2) sriov-agent: resource_provider_hypervisors, for example:
    
    [sriov_nic]
    bridge_mappings = physnet1:ens5,...
    resource_provider_bandwidths = ens5:10000000:10000000,...
    resource_provider_hypervisors = ens5:hypervisor1,...
    
    For both agents 'resource_provider_hypervisors' values default to
    socket.gethostname() for each key in resource_provider_bandwidths.
    
    We try to not block later developments in which one neutron
    agent may manage devices on multiple hosts. That's why we allow
    the each physdev to be associated with a different hypervisor.
    
    But here we do not try to solve the problem that the natural physdev
    identifiers may not be unique accross multiple hosts. We leave solving
    this problem to whoever wants to implement an agent handling devices of
    multiple hosts.
    
    (3) We extend report_state message's configurations field alike:
    
    {
    'bridge_mappings': {'physnet0': 'br-physnet0'},
    'resource_provider_bandwidths': {
        'br-physnet0': {'egress': 10000000, 'ingress': 10000000}},
    'resource_provider_hypervisors': {'br-physnet0': 'hypervisor0'},
    ...
    }
    
    (4) In neutron-server we use
    report_state.configurations.resource_provider_hypervisors.PHYSDEV
    when selecting parent resource provider for agent and physdev
    RP-tree. When not available in the message we fall back to using
    report_state.host as before.
    
    Since we only changed the free-format configurations field of the
    report_state message rpc version is not bumped and we expect this
    change to be backported to stein and train.
    
    Removed unapplicable TODO notes from backport.
    
    Change-Id: I9b08a3a9c20b702b745b41d4885fb5120fd665ce
    Closes-Bug: #1853840
    (cherry picked from commit 258eebea71b1cac37badf429a90d5cf57e4c455c)