yahoo-eng-team team mailing list archive

[Flavio Fernandes <1921491@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

While using a ml2/ovn deployment, there is no need for using RPC based DHCP, since that is
handled via ovn-controller. Still, we currently enable DhcpAgentNotifyAPI unconditionally [0], 
which seems wrong.

One side effect of that is that we periodically see the following warning log. Good news is that
this does not seem to be breaking anything.

2021-03-25 20:23:59.155 28 WARNING
neutron.scheduler.dhcp_agent_scheduler [req-d28046f6-897a-4644-a64e-
8338b81d0676 72126141799d44f6a82b803bde3ed144
b3d574eefb1b4eba88ba2b93a2b3cd21 - default default] No more DHCP agents

2021-03-25 20:23:59.158 28 WARNING
neutron.api.rpc.agentnotifiers.dhcp_rpc_agent_api [req-
d28046f6-897a-4644-a64e-8338b81d0676 72126141799d44f6a82b803bde3ed144
b3d574eefb1b4eba88ba2b93a2b3cd21 - default default] Unable to schedule
network c578ba7a-156a-4ec5-b7c9-37aeba1331d3: no agents available; will
retry on subsequent port and subnet creation events.

According to Rodolfo, we must be careful in adding a conditional to that
code, so it does not adversely affect nova.

He also points out that there is a flag that may be what we can use for this.
"""
<ralonsoh> so, IMO, we should make this conditional
<ralonsoh> (or maybe that's more complicated, we need to know that no compute is running a DHCP agent)
<ralonsoh> but be careful: we cannot disable this if we don't know any compute is not using dhcp agents
<ralonsoh> there is a flag (in master) cfg.CONF.enable_traditional_dhcp
<ralonsoh> used to enable/disable this RPC
<ralonsoh> related to the DHCP server on OVS (a new feature not merged yet)
<ralonsoh> we can implement something similar
"""

[0]:
https://github.com/openstack/neutron/blob/de3681ed3b0d0a54f0b8b59628fa50f25d5e737e/neutron/plugins/ml2/plugin.py#L325-L327

** Affects: neutron
     Importance: Medium
         Status: New

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https://bugs.launchpad.net/bugs/1921491

Title:
  ml2/ovn should not be calling
  neutron.api.rpc.agentnotifiers.dhcp_rpc_agent_api

Status in neutron:
  New

Bug description:
  While using a ml2/ovn deployment, there is no need for using RPC based DHCP, since that is
  handled via ovn-controller. Still, we currently enable DhcpAgentNotifyAPI unconditionally [0], 
  which seems wrong.

  One side effect of that is that we periodically see the following warning log. Good news is that
  this does not seem to be breaking anything.

  2021-03-25 20:23:59.155 28 WARNING
  neutron.scheduler.dhcp_agent_scheduler [req-d28046f6-897a-4644-a64e-
  8338b81d0676 72126141799d44f6a82b803bde3ed144
  b3d574eefb1b4eba88ba2b93a2b3cd21 - default default] No more DHCP
  agents

  2021-03-25 20:23:59.158 28 WARNING
  neutron.api.rpc.agentnotifiers.dhcp_rpc_agent_api [req-
  d28046f6-897a-4644-a64e-8338b81d0676 72126141799d44f6a82b803bde3ed144
  b3d574eefb1b4eba88ba2b93a2b3cd21 - default default] Unable to schedule
  network c578ba7a-156a-4ec5-b7c9-37aeba1331d3: no agents available;
  will retry on subsequent port and subnet creation events.

  According to Rodolfo, we must be careful in adding a conditional to
  that code, so it does not adversely affect nova.

  He also points out that there is a flag that may be what we can use for this.
  """
  <ralonsoh> so, IMO, we should make this conditional
  <ralonsoh> (or maybe that's more complicated, we need to know that no compute is running a DHCP agent)
  <ralonsoh> but be careful: we cannot disable this if we don't know any compute is not using dhcp agents
  <ralonsoh> there is a flag (in master) cfg.CONF.enable_traditional_dhcp
  <ralonsoh> used to enable/disable this RPC
  <ralonsoh> related to the DHCP server on OVS (a new feature not merged yet)
  <ralonsoh> we can implement something similar
  """

  [0]:
  https://github.com/openstack/neutron/blob/de3681ed3b0d0a54f0b8b59628fa50f25d5e737e/neutron/plugins/ml2/plugin.py#L325-L327

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