87a36cacc6
The tag and tag_ext extensions are deprecated for removal, but are not used widely today [1]. Rather than rehoming these extensions to neutron-lib and carrying out their deprecation life-cycle for no apparent reason, this patch proposes we just remove them now. While [2] initially removed these extensions, we had to revert them with [3]. Depends-On: I295a5b84eb7fa3439561fa009b7499f94d8df4d2 [1] http://codesearch.openstack.org/?q=from%20neutron.extensions%20import%20(tag_ext%7Ctag) [2] I0d7bcd789b468b1dd3f7ea13e6751a46203d6778 [3] If16443616eee703b66d57b6422dd451a443fbc64 Change-Id: I97095453610fff114d999a526d67e78119546ff5
25 KiB
High-availability for DHCP
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 openstack extension list command to check if these
extensions are enabled. Check agent and
agent_scheduler are included in the output.
$ openstack extension list --network -c Name -c Alias
+-------------------------------------------------------------+---------------------------+
| Name | Alias |
+-------------------------------------------------------------+---------------------------+
| Default Subnetpools | default-subnetpools |
| Network IP Availability | network-ip-availability |
| Network Availability Zone | network_availability_zone |
| Auto Allocated Topology Services | auto-allocated-topology |
| Neutron L3 Configurable external gateway mode | ext-gw-mode |
| Port Binding | binding |
| Neutron Metering | metering |
| agent | agent |
| Subnet Allocation | subnet_allocation |
| L3 Agent Scheduler | l3_agent_scheduler |
| Neutron external network | external-net |
| Neutron Service Flavors | flavors |
| Network MTU | net-mtu |
| Availability Zone | availability_zone |
| Quota management support | quotas |
| HA Router extension | l3-ha |
| Provider Network | provider |
| Multi Provider Network | multi-provider |
| Address scope | address-scope |
| Neutron Extra Route | extraroute |
| Subnet service types | subnet-service-types |
| Resource timestamps | standard-attr-timestamp |
| Neutron Service Type Management | service-type |
| Router Flavor Extension | l3-flavors |
| Neutron Extra DHCP opts | extra_dhcp_opt |
| Resource revision numbers | standard-attr-revisions |
| Pagination support | pagination |
| Sorting support | sorting |
| security-group | security-group |
| DHCP Agent Scheduler | dhcp_agent_scheduler |
| Router Availability Zone | router_availability_zone |
| RBAC Policies | rbac-policies |
| standard-attr-description | standard-attr-description |
| Neutron L3 Router | router |
| Allowed Address Pairs | allowed-address-pairs |
| project_id field enabled | project-id |
| Distributed Virtual Router | dvr |
+-------------------------------------------------------------+---------------------------+Demo setup
There will be three hosts in the setup.
| Host | Description |
|---|---|
| OpenStack controller host - controlnode | 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 |
Configuration
controlnode: neutron server
Neutron configuration file
/etc/neutron/neutron.conf:[DEFAULT] core_plugin = linuxbridge rabbit_host = controlnode allow_overlapping_ips = True host = controlnode agent_down_time = 5 dhcp_agents_per_network = 1Note
In the above configuration, we use
dhcp_agents_per_network = 1for this demonstration. In usual deployments, we suggest settingdhcp_agents_per_networkto more than one to match the number of DHCP agents in your deployment. Seeconf-dhcp-agents-per-network.Update the plug-in configuration file
/etc/neutron/plugins/linuxbridge/linuxbridge_conf.ini:[vlans] tenant_network_type = vlan network_vlan_ranges = physnet1:1000:2999 [database] connection = mysql+pymysql://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:[DEFAULT] rabbit_host = controlnode rabbit_password = openstack # host = HostB on hostb host = HostAUpdate the plug-in configuration file
/etc/neutron/plugins/linuxbridge/linuxbridge_conf.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:eth0Update the nova configuration file
/etc/nova/nova.conf:[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://203.0.113.10:9696/
HostA and HostB: DHCP agent
Update the DHCP configuration file
/etc/neutron/dhcp_agent.ini:[DEFAULT] interface_driver = neutron.agent.linux.interface.BridgeInterfaceDriver
Prerequisites for demonstration
Admin role is required to use the agent management and scheduler extensions. Ensure you run the following commands under a project with an admin role.
To experiment, you need VMs and a neutron network:
$ openstack server list
+--------------------------------------+-----------+--------+----------------+------------+
| ID | Name | Status | Networks | Image Name |
+--------------------------------------+-----------+--------+----------------+------------+
| c394fcd0-0baa-43ae-a793-201815c3e8ce | myserver1 | ACTIVE | net1=192.0.2.3 | cirros |
| 2d604e05-9a6c-4ddb-9082-8a1fbdcc797d | myserver2 | ACTIVE | net1=192.0.2.4 | ubuntu |
| c7c0481c-3db8-4d7a-a948-60ce8211d585 | myserver3 | ACTIVE | net1=192.0.2.5 | centos |
+--------------------------------------+-----------+--------+----------------+------------+
$ openstack network list
+--------------------------------------+------+--------------------------------------+
| ID | Name | Subnets |
+--------------------------------------+------+--------------------------------------+
| ad88e059-e7fa-4cf7-8857-6731a2a3a554 | net1 | 8086db87-3a7a-4cad-88c9-7bab9bc69258 |
+--------------------------------------+------+--------------------------------------+Managing agents in neutron deployment
List all agents:
$ openstack network agent list +--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+ | ID | Agent Type | Host | Availability Zone | Alive | State | Binary | +--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+ | 22467163-01ea-4231-ba45-3bd316f425e6 | Linux bridge agent | HostA | None | True | UP | neutron-linuxbridge-agent | | 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b | DHCP agent | HostA | None | True | UP | neutron-dhcp-agent | | 3066d20c-9f8f-440c-ae7c-a40ffb4256b6 | Linux bridge agent | HostB | nova | True | UP | neutron-linuxbridge-agent | | 55569f4e-6f31-41a6-be9d-526efce1f7fe | DHCP agent | HostB | nova | True | UP | neutron-dhcp-agent | +--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+Every agent that supports these extensions will register itself with the neutron server when it starts up.
The output shows information for four agents. The
alivefield showsTrueif the agent reported its state within the period defined by theagent_down_timeoption in theneutron.conffile. Otherwise thealiveisFalse.List DHCP agents that host a specified network:
$ openstack network agent list --network net1 +--------------------------------------+---------------+----------------+-------+ | ID | Host | Admin State Up | Alive | +--------------------------------------+---------------+----------------+-------+ | 22467163-01ea-4231-ba45-3bd316f425e6 | HostA | UP | True | +--------------------------------------+---------------+----------------+-------+List the networks hosted by a given DHCP agent:
This command is to show which networks a given dhcp agent is managing.
$ openstack network list --agent 22467163-01ea-4231-ba45-3bd316f425e6 +--------------------------------+------------------------+---------------------------------+ | ID | Name | Subnets | +--------------------------------+------------------------+---------------------------------+ | ad88e059-e7fa- | net1 | 8086db87-3a7a-4cad- | | 4cf7-8857-6731a2a3a554 | | 88c9-7bab9bc69258 | +--------------------------------+------------------------+---------------------------------+Show agent details.
The
openstack network agent showcommand shows details for a specified agent:$ openstack network agent show 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b +---------------------+--------------------------------------------------+ | Field | Value | +---------------------+--------------------------------------------------+ | admin_state_up | UP | | agent_type | DHCP agent | | alive | True | | availability_zone | nova | | binary | neutron-dhcp-agent | | configurations | dhcp_driver='neutron.agent.linux.dhcp.Dnsmasq', | | | dhcp_lease_duration='86400', | | | log_agent_heartbeats='False', networks='1', | | | notifies_port_ready='True', ports='3', | | | subnets='1' | | created_at | 2016-12-14 00:25:54 | | description | None | | last_heartbeat_at | 2016-12-14 06:53:24 | | host | HostA | | id | 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b | | started_at | 2016-12-14 00:25:54 | | topic | dhcp_agent | +---------------------+--------------------------------------------------+In this output,
last_heartbeat_atis the time on the neutron server. You do not need to synchronize all agents to this time for this extension to run correctly.configurationsdescribes 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:
$ openstack network agent show 22467163-01ea-4231-ba45-3bd316f425e6 +---------------------+--------------------------------------+ | Field | Value | +---------------------+--------------------------------------+ | admin_state_up | UP | | agent_type | Linux bridge agent | | alive | True | | availability_zone | nova | | binary | neutron-linuxbridge-agent | | configurations | { | | | "physnet1": "eth0", | | | "devices": "4" | | | } | | created_at | 2016-12-14 00:26:54 | | description | None | | last_heartbeat_at | 2016-12-14 06:53:24 | | host | HostA | | id | 22467163-01ea-4231-ba45-3bd316f425e6 | | started_at | 2016-12-14T06:48:39.000000 | | topic | N/A | +---------------------+--------------------------------------+The output shows
bridge-mappingand the number of virtual network devices on this L2 agent.
Managing assignment of networks to DHCP agent
A single network can be assigned to more than one DHCP agents and one DHCP agent can host more than one network. You can add a network to a DHCP agent and remove one from it.
Default scheduling.
When you create a network with one port, the network will be scheduled 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.
$ openstack network create net2 $ openstack subnet create --network net2 --subnet-range 198.51.100.0/24 subnet2 $ openstack port create port2 --network net2 $ openstack network agent list --network net2 +--------------------------------------+---------------+----------------+-------+ | ID | Host | Admin State Up | Alive | +--------------------------------------+---------------+----------------+-------+ | 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b | HostA | UP | True | +--------------------------------------+---------------+----------------+-------+It is allocated to DHCP agent on HostA. If you want to validate the behavior through the
dnsmasqcommand, 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:
$ openstack network agent add network --dhcp \ 55569f4e-6f31-41a6-be9d-526efce1f7fe net2 $ openstack network agent list --network net2 +--------------------------------------+-------+----------------+--------+ | ID | Host | Admin State Up | Alive | +--------------------------------------+-------+----------------+--------+ | 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b | HostA | UP | True | | 55569f4e-6f31-41a6-be9d-526efce1f7fe | HostB | UP | True | +--------------------------------------+-------+----------------+--------+Both DHCP agents host the
net2network.Remove a network from a specified DHCP agent.
This command is the sibling command for the previous one. Remove
net2from the DHCP agent for HostA:$ openstack network agent remove network --dhcp \ 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b net2 $ openstack network agent list --network net2 +--------------------------------------+-------+----------------+-------+ | ID | Host | Admin State Up | Alive | +--------------------------------------+-------+----------------+-------+ | 55569f4e-6f31-41a6-be9d-526efce1f7fe | HostB | UP | True | +--------------------------------------+-------+----------------+-------+You can see that only the DHCP agent for HostB is hosting the
net2network.
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:$ openstack network list +--------------------------------------+------+--------------------------------------+ | ID | Name | Subnets | +--------------------------------------+------+--------------------------------------+ | ad88e059-e7fa-4cf7-8857-6731a2a3a554 | net1 | 8086db87-3a7a-4cad-88c9-7bab9bc69258 | | 9b96b14f-71b8-4918-90aa-c5d705606b1a | net2 | 6979b71a-0ae8-448c-aa87-65f68eedcaaa | +--------------------------------------+------+--------------------------------------+ $ openstack server create --image tty --flavor 1 myserver4 \ --nic net-id=9b96b14f-71b8-4918-90aa-c5d705606b1a ... $ openstack server list +--------------------------------------+-----------+--------+-------------------+------------+ | ID | Name | Status | Networks | Image Name | +--------------------------------------+-----------+--------+-------------------+------------+ | c394fcd0-0baa-43ae-a793-201815c3e8ce | myserver1 | ACTIVE | net1=192.0.2.3 | cirros | | 2d604e05-9a6c-4ddb-9082-8a1fbdcc797d | myserver2 | ACTIVE | net1=192.0.2.4 | ubuntu | | c7c0481c-3db8-4d7a-a948-60ce8211d585 | myserver3 | ACTIVE | net1=192.0.2.5 | centos | | f62f4731-5591-46b1-9d74-f0c901de567f | myserver4 | ACTIVE | net2=198.51.100.2 | cirros1 | +--------------------------------------+-----------+--------+-------------------+------------+Make sure both DHCP agents hosting
net2:Use the previous commands to assign the network to agents.
$ openstack network agent list --network net2 +--------------------------------------+-------+----------------+-------+ | ID | Host | Admin State Up | Alive | +--------------------------------------+-------+----------------+-------+ | 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b | HostA | UP | True | | 55569f4e-6f31-41a6-be9d-526efce1f7fe | HostB | UP | True | +--------------------------------------+-------+----------------+-------+
To test the HA of DHCP agent:
- Log in to the
myserver4VM, and runudhcpc,dhclientor other DHCP client. - Stop the DHCP agent on HostA. Besides stopping the
neutron-dhcp-agentbinary, you must stop thednsmasqprocesses. - Run a DHCP client in VM to see if it can get the wanted IP.
- Stop the DHCP agent on HostB too.
- Run
udhcpcin the VM; it cannot get the wanted IP. - Start DHCP agent on HostB. The VM gets the wanted IP again.
Disabling and removing 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. Even after disabling the agent, resources on the agent are kept assigned. Ensure you remove the resources on the agent before you delete the agent.
Disable the DHCP agent on HostA before you stop it:
$ openstack network agent set 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b --disable
$ openstack network agent list
+--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+
| ID | Agent Type | Host | Availability Zone | Alive | State | Binary |
+--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+
| 22467163-01ea-4231-ba45-3bd316f425e6 | Linux bridge agent | HostA | None | True | UP | neutron-linuxbridge-agent |
| 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b | DHCP agent | HostA | None | True | DOWN | neutron-dhcp-agent |
| 3066d20c-9f8f-440c-ae7c-a40ffb4256b6 | Linux bridge agent | HostB | nova | True | UP | neutron-linuxbridge-agent |
| 55569f4e-6f31-41a6-be9d-526efce1f7fe | DHCP agent | HostB | nova | True | UP | neutron-dhcp-agent |
+--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+After you stop the DHCP agent on HostA, you can delete it by the following command:
$ openstack network agent delete 2444c54d-0d28-460c-ab0f-cd1e6b5d3c7b
$ openstack network agent list
+--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+
| ID | Agent Type | Host | Availability Zone | Alive | State | Binary |
+--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+
| 22467163-01ea-4231-ba45-3bd316f425e6 | Linux bridge agent | HostA | None | True | UP | neutron-linuxbridge-agent |
| 3066d20c-9f8f-440c-ae7c-a40ffb4256b6 | Linux bridge agent | HostB | nova | True | UP | neutron-linuxbridge-agent |
| 55569f4e-6f31-41a6-be9d-526efce1f7fe | DHCP agent | HostB | nova | True | UP | neutron-dhcp-agent |
+--------------------------------------+--------------------+-------+-------------------+-------+-------+---------------------------+After deletion, if you restart the DHCP agent, it appears on the agent list again.
Enabling DHCP high availability by default
You can control the default number of DHCP agents assigned to a
network by setting the following configuration option in the file
/etc/neutron/neutron.conf.
dhcp_agents_per_network = 3