openstack/openstack-manuals
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Move DHCP HA section to Networking Guide

Browse Source 
In order to support better all networking documentation.
This sub-section has been moved to the Netwoking Guide and properly
backported to Mitaka.
https://review.openstack.org/#/c/323528/

Change-Id: I9b83ad6f7540a679fdc07cde7eeddb29696823c4
This commit is contained in:
Edgar Magana 2016-05-31 22:12:00 -07:00
parent 0bed31d994
commit 5a3901e36b
2 changed files with 2 additions and 482 deletions
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Scalable and highly available DHCP agents
=========================================
This section describes how to use the agent management (alias agent) and
scheduler (alias agent_scheduler) extensions for DHCP agents
scalability and HA.
.. note::
Use the :command:`neutron ext-list` client command to check if these
extensions are enabled:
.. code-block:: console
$ neutron ext-list -c name -c alias
+-----------------+--------------------------+
| alias | name |
+-----------------+--------------------------+
| agent_scheduler | Agent Schedulers |
| binding | Port Binding |
| quotas | Quota management support |
| agent | agent |
| provider | Provider Network |
| router | Neutron L3 Router |
| lbaas | Load Balancing service |
| extraroute | Neutron Extra Route |
+-----------------+--------------------------+
.. figure:: figures/demo_multiple_dhcp_agents.png
There will be three hosts in the setup.
.. list-table::
:widths: 25 50
:header-rows: 1
* - Host
- Description
* - OpenStack controller host - controlnod
- Runs the Networking, Identity, and Compute services that are required
to deploy VMs. The node must have at least one network interface that
is connected to the Management Network. Note that ``nova-network`` should
not be running because it is replaced by Neutron.
* - HostA
- Runs ``nova-compute``, the Neutron L2 agent and DHCP agent
* - HostB
- Same as HostA
**Hosts for demo**
Configuration
~~~~~~~~~~~~~
**controlnode: neutron server**
#. Neutron configuration file ``/etc/neutron/neutron.conf``:
.. code-block:: ini
[DEFAULT]
core_plugin = linuxbridge
rabbit_host = controlnode
allow_overlapping_ips = True
host = controlnode
agent_down_time = 5
#. Update the plug-in configuration file
``/etc/neutron/plugins/linuxbridge/linuxbridge_conf.ini``:
.. code-block:: ini
[vlans]
tenant_network_type = vlan
network_vlan_ranges = physnet1:1000:2999
[database]
connection = mysql://root:root@127.0.0.1:3306/neutron_linux_bridge
retry_interval = 2
[linux_bridge]
physical_interface_mappings = physnet1:eth0
**HostA and HostB: L2 agent**
#. Neutron configuration file ``/etc/neutron/neutron.conf``:
.. code-block:: ini
[DEFAULT]
rabbit_host = controlnode
rabbit_password = openstack
# host = HostB on hostb
host = HostA
#. Update the plug-in configuration file
``/etc/neutron/plugins/linuxbridge/linuxbridge_conf.ini``:
.. code-block:: ini
[vlans]
tenant_network_type = vlan
network_vlan_ranges = physnet1:1000:2999
[database]
connection = mysql://root:root@127.0.0.1:3306/neutron_linux_bridge
retry_interval = 2
[linux_bridge]
physical_interface_mappings = physnet1:eth0
#. Update the nova configuration file ``/etc/nova/nova.conf``:
.. code-block:: ini
[DEFAULT]
use_neutron=True
firewall_driver=nova.virt.firewall.NoopFirewallDriver
[neutron]
admin_username=neutron
admin_password=servicepassword
admin_auth_url=http://controlnode:35357/v2.0/
auth_strategy=keystone
admin_tenant_name=servicetenant
url=http://100.1.1.10:9696/
**HostA and HostB: DHCP agent**
- Update the DHCP configuration file ``/etc/neutron/dhcp_agent.ini``:
.. code-block:: ini
[DEFAULT]
interface_driver = neutron.agent.linux.interface.BridgeInterfaceDriver
Commands in agent management and scheduler extensions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following commands require the tenant running the command to have an
admin role.
.. note::
Ensure that the following environment variables are set. These are
used by the various clients to access the Identity service.
.. code-block:: bash
export OS_USERNAME=admin
export OS_PASSWORD=adminpassword
export OS_TENANT_NAME=admin
export OS_AUTH_URL=http://controlnode:5000/v2.0/
**Settings**
To experiment, you need VMs and a neutron network:
.. code-block:: console
$ nova list
+-------------------------------------+----------+--------+--------------+
| ID | Name | Status | Networks |
+-------------------------------------+----------+--------+--------------+
| c394fcd0-0baa-43ae-a793-201815c3e8ce| myserver1| ACTIVE | net1=10.0.1.3|
| 2d604e05-9a6c-4ddb-9082-8a1fbdcc797d| myserver2| ACTIVE | net1=10.0.1.4|
| c7c0481c-3db8-4d7a-a948-60ce8211d585| myserver3| ACTIVE | net1=10.0.1.5|
+-------------------------------------+----------+--------+--------------+
$ neutron net-list
+-------------------------+------+--------------------------------------+
| id | name | subnets |
+-------------------------+------+--------------------------------------+
| 89dca1c6-c7d4-4f7a- | | |
| b730-549af0fb6e34 | net1 | f6c832e3-9968-46fd-8e45-d5cf646db9d1 |
+-------------------------+------+--------------------------------------+
**Manage agents in neutron deployment**
Every agent that supports these extensions will register itself with the
neutron server when it starts up.
#. List all agents:
.. code-block:: console
$ neutron agent-list
+--------------------------------------+--------------------+-------+-------+----------------+
| id | agent_type | host | alive | admin_state_up |
+--------------------------------------+--------------------+-------+-------+----------------+
| 1b69828d-6a9b-4826-87cd-1757f0e27f31 | Linux bridge agent | HostA | :-) | True |
| a0c1c21c-d4f4-4577-9ec7-908f2d48622d | DHCP agent | HostA | :-) | True |
| ed96b856-ae0f-4d75-bb28-40a47ffd7695 | Linux bridge agent | HostB | :-) | True |
| f28aa126-6edb-4ea5-a81e-8850876bc0a8 | DHCP agent | HostB | :-) | True |
+--------------------------------------+--------------------+-------+-------+----------------+
The output shows information for four agents. The ``alive`` field shows
``:-)`` if the agent reported its state within the period defined by the
``agent_down_time`` option in the ``neutron.conf`` file. Otherwise the
``alive`` is ``xxx``.
#. List the DHCP agents that host a specified network:
In some deployments, one DHCP agent is not enough to hold all network
data. In addition, you must have a backup for it even when the
deployment is small. The same network can be assigned to more than one
DHCP agent and one DHCP agent can host more than one network.
#. List DHCP agents that host a specified network:
.. code-block:: console
$ neutron dhcp-agent-list-hosting-net net1
+--------------------------------------+-------+----------------+-------+
| id | host | admin_state_up | alive |
+--------------------------------------+-------+----------------+-------+
| a0c1c21c-d4f4-4577-9ec7-908f2d48622d | HostA | True | :-) |
+--------------------------------------+-------+----------------+-------+
#. List the networks hosted by a given DHCP agent:
This command is to show which networks a given dhcp agent is managing.
.. code-block:: console
$ neutron net-list-on-dhcp-agent a0c1c21c-d4f4-4577-9ec7-908f2d48622d
+------------------------+------+---------------------------------+
| id | name | subnets |
+------------------------+------+---------------------------------+
| 89dca1c6-c7d4-4f7a | | |
| -b730-549af0fb6e34 | net1 | f6c832e3-9968-46fd |
| | | -8e45-d5cf646db9d1 10.0.1.0/24 |
+------------------------+------+---------------------------------+
#. Show agent details.
The :command:`agent-show` command shows details for a specified agent:
.. code-block:: console
$ neutron agent-show a0c1c21c-d4f4-4577-9ec7-908f2d48622d
+--------------------+---------------------------------------------------+
| Field | Value |
+--------------------+---------------------------------------------------+
| admin_state_up | True |
| agent_type | DHCP agent |
| alive | False |
| binary | neutron-dhcp-agent |
| configurations |{ |
| | "subnets": 1, |
| | "dhcp_driver": "neutron.agent.linux.dhcp.Dnsmasq",|
| | "networks": 1, |
| | "dhcp_lease_time": 120, |
| | "ports": 3 |
| |} |
| created_at | 2013-03-16T01:16:18.000000 |
| description | |
| heartbeat_timestamp| 2013-03-17T01:37:22.000000 |
| host | HostA |
| id | 58f4ce07-6789-4bb3-aa42-ed3779db2b03 |
| started_at | 2013-03-16T06:48:39.000000 |
| topic | dhcp_agent |
+--------------------+---------------------------------------------------+
In this output, ``heartbeat_timestamp`` is the time on the neutron
server. You do not need to synchronize all agents to this time for this
extension to run correctly. ``configurations`` describes the static
configuration for the agent or run time data. This agent is a DHCP agent
and it hosts one network, one subnet, and three ports.
Different types of agents show different details. The following output
shows information for a Linux bridge agent:
.. code-block:: console
$ neutron agent-show ed96b856-ae0f-4d75-bb28-40a47ffd7695
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| admin_state_up | True |
| binary | neutron-linuxbridge-agent |
| configurations | { |
| | "physnet1": "eth0", |
| | "devices": "4" |
| | } |
| created_at | 2013-03-16T01:49:52.000000 |
| description | |
| disabled | False |
| group | agent |
| heartbeat_timestamp | 2013-03-16T01:59:45.000000 |
| host | HostB |
| id | ed96b856-ae0f-4d75-bb28-40a47ffd7695 |
| topic | N/A |
| started_at | 2013-03-16T06:48:39.000000 |
| type | Linux bridge agent |
+---------------------+--------------------------------------+
The output shows ``bridge-mapping`` and the number of virtual network
devices on this L2 agent.
**Manage assignment of networks to DHCP agent**
Now that you have run the :command:`net-list-on-dhcp-agent` and
:command:`dhcp-agent-list-hosting-net` commands, you can add a network to a
DHCP agent and remove one from it.
#. Default scheduling.
When you create a network with one port, you can schedule it to an
active DHCP agent. If many active DHCP agents are running, select one
randomly. You can design more sophisticated scheduling algorithms in the
same way as nova-schedule later on.
.. code-block:: console
$ neutron net-create net2
$ neutron subnet-create net2 9.0.1.0/24 --name subnet2
$ neutron port-create net2
$ neutron dhcp-agent-list-hosting-net net2
+--------------------------------------+-------+----------------+-------+
| id | host | admin_state_up | alive |
+--------------------------------------+-------+----------------+-------+
| a0c1c21c-d4f4-4577-9ec7-908f2d48622d | HostA | True | :-) |
+--------------------------------------+-------+----------------+-------+
It is allocated to DHCP agent on HostA. If you want to validate the
behavior through the :command:`dnsmasq` command, you must create a subnet for
the network because the DHCP agent starts the dnsmasq service only if
there is a DHCP.
#. Assign a network to a given DHCP agent.
To add another DHCP agent to host the network, run this command:
.. code-block:: console
$ neutron dhcp-agent-network-add f28aa126-6edb-4ea5-a81e-8850876bc0a8 net2
Added network net2 to dhcp agent
$ neutron dhcp-agent-list-hosting-net net2
+--------------------------------------+-------+----------------+-------+
| id | host | admin_state_up | alive |
+--------------------------------------+-------+----------------+-------+
| a0c1c21c-d4f4-4577-9ec7-908f2d48622d | HostA | True | :-) |
| f28aa126-6edb-4ea5-a81e-8850876bc0a8 | HostB | True | :-) |
+--------------------------------------+-------+----------------+-------+
Both DHCP agents host the ``net2`` network.
#. Remove a network from a specified DHCP agent.
This command is the sibling command for the previous one. Remove
``net2`` from the DHCP agent for HostA:
.. code-block:: console
$ neutron dhcp-agent-network-remove a0c1c21c-d4f4-4577-9ec7-908f2d48622d \
net2
Removed network net2 to dhcp agent
$ neutron dhcp-agent-list-hosting-net net2
+--------------------------------------+-------+----------------+-------+
| id | host | admin_state_up | alive |
+--------------------------------------+-------+----------------+-------+
| f28aa126-6edb-4ea5-a81e-8850876bc0a8 | HostB | True | :-) |
+--------------------------------------+-------+----------------+-------+
You can see that only the DHCP agent for HostB is hosting the ``net2``
network.
**HA of DHCP agents**
Boot a VM on net2. Let both DHCP agents host ``net2``. Fail the agents
in turn to see if the VM can still get the desired IP.
#. Boot a VM on net2:
.. code-block:: console
$ neutron net-list
+-------------------------+------+-----------------------------+
| id | name | subnets |
+-------------------------+------+-----------------------------+
| 89dca1c6-c7d4-4f7a- | | |
| b730-549af0fb6e34 | net1 | f6c832e3-9968-46fd-8e45 |
| | | -d5cf646db9d1 10.0.1.0/24 |
| 9b96b14f-71b8-4918-90aa-| | |
| c5d705606b1a | net2 | 6979b71a-0ae8-448c-aa87- |
| | | 65f68eedcaaa 9.0.1.0/24 |
+-------------------------+------+-----------------------------+
.. code-block:: console
$ nova boot --image tty --flavor 1 myserver4 \
--nic net-id=9b96b14f-71b8-4918-90aa-c5d705606b1a
.. code-block:: console
$ nova list
+-------------------------------------+----------+-------+---------------+
| ID | Name | Status| Networks |
+-------------------------------------+----------+-------+---------------+
|c394fcd0-0baa-43ae-a793-201815c3e8ce |myserver1 |ACTIVE | net1=10.0.1.3 |
|2d604e05-9a6c-4ddb-9082-8a1fbdcc797d |myserver2 |ACTIVE | net1=10.0.1.4 |
|c7c0481c-3db8-4d7a-a948-60ce8211d585 |myserver3 |ACTIVE | net1=10.0.1.5 |
|f62f4731-5591-46b1-9d74-f0c901de567f |myserver4 |ACTIVE | net2=9.0.1.2 |
+-------------------------------------+----------+-------+---------------+
#. Make sure both DHCP agents hosting ``net2``:
Use the previous commands to assign the network to agents.
.. code-block:: console
$ neutron dhcp-agent-list-hosting-net net2
+--------------------------------------+-------+----------------+-------+
| id | host | admin_state_up | alive |
+--------------------------------------+-------+----------------+-------+
| a0c1c21c-d4f4-4577-9ec7-908f2d48622d | HostA | True | :-) |
| f28aa126-6edb-4ea5-a81e-8850876bc0a8 | HostB | True | :-) |
+--------------------------------------+-------+----------------+-------+
**Test the HA**
#. Log in to the ``myserver4`` VM, and run ``udhcpc``, ``dhclient`` or
other DHCP client.
#. Stop the DHCP agent on HostA. Besides stopping the
``neutron-dhcp-agent`` binary, you must stop the ``dnsmasq`` processes.
#. Run a DHCP client in VM to see if it can get the wanted IP.
#. Stop the DHCP agent on HostB too.
#. Run ``udhcpc`` in the VM; it cannot get the wanted IP.
#. Start DHCP agent on HostB. The VM gets the wanted IP again.
**Disable and remove an agent**
An administrator might want to disable an agent if a system hardware or
software upgrade is planned. Some agents that support scheduling also
support disabling and enabling agents, such as L3 and DHCP agents. After
the agent is disabled, the scheduler does not schedule new resources to
the agent. After the agent is disabled, you can safely remove the agent.
Remove the resources on the agent before you delete the agent.
To run the following commands, you must stop the DHCP agent on HostA.
.. code-block:: console
$ neutron agent-update --admin-state-up False \
a0c1c21c-d4f4-4577-9ec7-908f2d48622d
$ neutron agent-list
+--------------------------------------+--------------------+-------+-------+----------------+
| id | agent_type | host | alive | admin_state_up |
+--------------------------------------+--------------------+-------+-------+----------------+
| 1b69828d-6a9b-4826-87cd-1757f0e27f31 | Linux bridge agent | HostA | :-) | True |
| a0c1c21c-d4f4-4577-9ec7-908f2d48622d | DHCP agent | HostA | :-) | False |
| ed96b856-ae0f-4d75-bb28-40a47ffd7695 | Linux bridge agent | HostB | :-) | True |
| f28aa126-6edb-4ea5-a81e-8850876bc0a8 | DHCP agent | HostB | :-) | True |
+--------------------------------------+--------------------+-------+-------+----------------+
.. code-block:: console
$ neutron agent-delete a0c1c21c-d4f4-4577-9ec7-908f2d48622d
Deleted agent: a0c1c21c-d4f4-4577-9ec7-908f2d48622d
$ neutron agent-list
+--------------------------------------+--------------------+-------+-------+----------------+
| id | agent_type | host | alive | admin_state_up |
+--------------------------------------+--------------------+-------+-------+----------------+
| 1b69828d-6a9b-4826-87cd-1757f0e27f31 | Linux bridge agent | HostA | :-) | True |
| ed96b856-ae0f-4d75-bb28-40a47ffd7695 | Linux bridge agent | HostB | :-) | True |
| f28aa126-6edb-4ea5-a81e-8850876bc0a8 | DHCP agent | HostB | :-) | True |
+--------------------------------------+--------------------+-------+-------+----------------+
After deletion, if you restart the DHCP agent, it appears on the agent
list again.
This section is fully described in the Networking Guide:
http://docs.openstack.org/mitaka/networking-guide/misc-add-ha-for-dhcp.html