Adding a compute node

Expanding your single-node OpenStack cloud to include a second compute node requires a second network adapter, if you want to separate the Neutron tenant network traffic.

Edit the answer file

First, edit the “answer file” generated during the initial Packstack setup. You’ll find the file in the directory from which you ran Packstack.

NOTE: by default, $youranswerfile is called packstack-answer-$date-$time.txt

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[root@openstack-controller ~]# ls packstack-answers-20160517-215941.txt
packstack-answers-20160517-215941.txt

Change IP addresses

Change the value for CONFIG_COMPUTE_HOSTS from the value of your first host IP address to the value of your second host IP address. Ensure that the key CONFIG_NETWORK_HOSTS exists and is set to the IP address of your first host.

Skip installing on an already existing servers

In case you do not want to run the installation over again on the already configured servers, add the following parameter to the answerfile:

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EXCLUDE_SERVERS=<serverIP>,<serverIP>,...

Example:

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[root@openstack-controller ~]# egrep "CONFIG_COMPUTE_HOSTS|CONFIG_NETWORK_HOSTS|EXCLUDE_SERVERS" packstack-answers-20160613-231012.txt
EXCLUDE_SERVERS=192.168.2.110
CONFIG_COMPUTE_HOSTS=192.168.2.110,192.168.2.111,192.168.2.112,192.168.2.113
CONFIG_NETWORK_HOSTS=192.168.2.110

Re-run packstack with the new values

Run packstack again, specifying your modified answer file:

NOTE: by default $youranswerfile is called packstack-answer-$date-$time.txt

Example:

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[root@openstack-controller ~]# cp packstack-answers-20160613-231012.txt packstack-answers-20160613-231012.txt.bak

[root@openstack-controller ~]# vi packstack-answers-20160613-231012.txt 

[root@openstack-controller ~]# egrep "CONFIG_COMPUTE_HOSTS|CONFIG_NETWORK_HOSTS|EXCLUDE_SERVERS" packstack-answers-20160613-231012.txt
EXCLUDE_SERVERS=192.168.2.110
CONFIG_COMPUTE_HOSTS=192.168.2.110,192.168.2.111,192.168.2.112,192.168.2.113
CONFIG_NETWORK_HOSTS=192.168.2.110

[root@openstack-controller ~]# sudo packstack --answer-file=packstack-answers-20160613-231012.txt

Dilatation Node

check new compute node openstack-compute-5

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# nova host-list
+----------------------+-------------+----------+
| host_name            | service     | zone     |
+----------------------+-------------+----------+
| openstack-controller | cert        | internal |
| openstack-controller | consoleauth | internal |
| openstack-controller | scheduler   | internal |
| openstack-controller | conductor   | internal |
| openstack-controller | compute     | nova     |
| openstack-compute-1  | compute     | nova     |
| openstack-compute-2  | compute     | nova     |
| openstack-compute-3  | compute     | nova     |
| openstack-compute-4  | compute     | nova     |
| openstack-compute-5  | compute     | nova     |
+----------------------+-------------+----------+

check Cloud-Host State

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# virsh list --all
 Id    Name                           State
----------------------------------------------------
 1     instance-00000032              running
 2     instance-00000030              running
 3     instance-00000010              running
 4     instance-0000000e              running
 5     instance-00000034              running

adding a compute node done. check service normal.

reference：https://www.rdoproject.org/install/adding-a-compute-node/