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Scaling your environment¶
This is a draft environment scaling page for the proposed OpenStack-Ansible operations guide.
Add a new infrastructure host¶
While three infrastructure hosts are recommended, if further hosts are needed in an environment, it is possible to create additional nodes.
Warning
Make sure you back up your current OpenStack environment before adding any new nodes. See Back up and restore your cloud for more information.
Add the node to the
infra_hosts
stanza of the/etc/openstack_deploy/openstack_user_config.yml
infra_hosts: [...] NEW_infra<node-ID>: ip: 10.17.136.32 NEW_infra<node-ID2>: ip: 10.17.136.33
Change to playbook folder on the deployment host.
# cd /opt/openstack-ansible/playbooks
Update the inventory to add new hosts. Make sure new rsyslog container names are updated. Send the updated results to
dev/null
.# /opt/openstack-ansible/inventory/dynamic_inventory.py > /dev/null
Create the
/root/add_host.limit
file, which contains all new node host names and their containers. Add localhost to the list of hosts to be able to access deployment host facts.localhost NEW_infra<node-ID> NEW_infra<node-ID2> NEW_infra<node-ID>_containers NEW_infra<node-ID2>_containers
Run the
setup-everything.yml
playbook with thelimit
argument.# openstack-ansible setup-everything.yml --limit @/root/add_host.limit
Test new infra nodes¶
After creating a new infra node, test that the node runs correctly by launching a new instance. Ensure that the new node can respond to a networking connection test through the ping command. Log in to your monitoring system, and verify that the monitors return a green signal for the new node.
Add a compute host¶
Use the following procedure to add a compute host to an operational cluster.
Configure the host as a target host. See the target hosts configuration section of the deploy guide. for more information.
Edit the
/etc/openstack_deploy/openstack_user_config.yml
file and add the host to thecompute_hosts
stanza.If necessary, also modify the
used_ips
stanza.If the cluster is utilizing Telemetry/Metering (ceilometer), edit the
/etc/openstack_deploy/conf.d/ceilometer.yml
file and add the host to themetering-compute_hosts
stanza.Run the following commands to add the host. Replace
NEW_HOST_NAME
with the name of the new host.# cd /opt/openstack-ansible/playbooks # openstack-ansible setup-hosts.yml --limit localhost,NEW_HOST_NAME # ansible nova_all -m setup -a 'filter=ansible_local gather_subset="!all"' # openstack-ansible setup-openstack.yml --limit localhost,NEW_HOST_NAME # openstack-ansible os-nova-install.yml --tags nova-key --limit nova_compute
Alternatively you can try using new compute nodes deployment script
/opt/openstack-ansible/scripts/add-compute.sh
.You can provide this script with extra tasks that will be executed before or right after OSA roles. To do so you should set environment variables
PRE_OSA_TASKS
orPOST_OSA_TASKS
with plays to run divided with semicolon:# export POST_OSA_TASKS="/opt/custom/setup.yml --limit HOST_NAME;/opt/custom/tasks.yml --tags deploy" # /opt/openstack-ansible/scripts/add-compute.sh HOST_NAME,HOST_NAME_2
Test new compute nodes¶
After creating a new node, test that the node runs correctly by launching an instance on the new node.
$ openstack server create --image IMAGE --flavor m1.tiny \
--key-name KEY --availability-zone ZONE:HOST:NODE \
--nic net-id=UUID SERVER
Ensure that the new instance can respond to a networking connection test through the ping command. Log in to your monitoring system, and verify that the monitors return a green signal for the new node.
Remove a compute host¶
The openstack-ansible-ops repository contains a playbook for removing a compute host from an OpenStack-Ansible environment. To remove a compute host, follow the below procedure.
Note
This guide describes how to remove a compute node from an OpenStack-Ansible environment completely. Perform these steps with caution, as the compute node will no longer be in service after the steps have been completed. This guide assumes that all data and instances have been properly migrated.
Disable all OpenStack services running on the compute node. This can include, but is not limited to, the
nova-compute
service and the neutron agent service.Note
Ensure this step is performed first
# Run these commands on the compute node to be removed # stop nova-compute # stop neutron-linuxbridge-agent
Clone the
openstack-ansible-ops
repository to your deployment host:$ git clone https://opendev.org/openstack/openstack-ansible-ops \ /opt/openstack-ansible-ops
Run the
remove_compute_node.yml
Ansible playbook with thehost_to_be_removed
user variable set:$ cd /opt/openstack-ansible-ops/ansible_tools/playbooks openstack-ansible remove_compute_node.yml \ -e host_to_be_removed="<name-of-compute-host>"
After the playbook completes, remove the compute node from the OpenStack-Ansible configuration file in
/etc/openstack_deploy/openstack_user_config.yml
.
Recover a compute host failure¶
The following procedure addresses Compute node failure if shared storage is used.
Note
If shared storage is not used, data can be copied from the
/var/lib/nova/instances
directory on the failed Compute node
${FAILED_NODE}
to another node ${RECEIVING_NODE}
before
performing the following procedure. Please note this method is
not supported.
Re-launch all instances on the failed node.
Invoke the MySQL command line tool
Generate a list of instance UUIDs hosted on the failed node:
mysql> select uuid from instances where host = '${FAILED_NODE}' and deleted = 0;
Set instances on the failed node to be hosted on a different node:
mysql> update instances set host ='${RECEIVING_NODE}' where host = '${FAILED_NODE}' \ and deleted = 0;
Reboot each instance on the failed node listed in the previous query to regenerate the XML files:
# nova reboot —hard $INSTANCE_UUID
Find the volumes to check the instance has successfully booted and is at the login :
mysql> select nova.instances.uuid as instance_uuid, cinder.volumes.id \ as voume_uuid, cinder.volumes.status, cinder.volumes.attach_status, \ cinder.volumes.mountpoint, cinder.volumes,display_name from \ cinder.volumes inner join nova.instances on cinder.volumes.instance_uuid=nova.instances.uuid \ where nova.instances.host = '${FAILED_NODE}';
If rows are found, detach and re-attach the volumes using the values listed in the previous query:
# nova volume-detach $INSTANCE_UUID $VOLUME_UUID && \ # nova volume-attach $INSTANCE_UUID $VOLUME_UUID $VOLUME_MOUNTPOINT
Rebuild or replace the failed node as described in add-compute-host.
Replacing failed hardware¶
It is essential to plan and know how to replace failed hardware in your cluster without compromising your cloud environment.
Consider the following to help establish a hardware replacement plan:
What type of node am I replacing hardware on?
Can the hardware replacement be done without the host going down? For example, a single disk in a RAID-10.
If the host DOES have to be brought down for the hardware replacement, how should the resources on that host be handled?
If you have a Compute (nova) host that has a disk failure on a RAID-10, you can swap the failed disk without powering the host down. On the other hand, if the RAM has failed, you would have to power the host down. Having a plan in place for how you will manage these types of events is a vital part of maintaining your OpenStack environment.
For a Compute host, shut down the instance on the host before it goes down. For a Block Storage (cinder) host using non-redundant storage, shut down any instances with volumes attached that require that mount point. Unmount the drive within your operating system and re-mount the drive once the Block Storage host is back online.
Shutting down the Compute host¶
If a Compute host needs to be shut down:
Disable the
nova-compute
binary:# nova service-disable --reason "Hardware replacement" HOSTNAME nova-compute
List all running instances on the Compute host:
# nova list --all-t --host <compute_name> | awk '/ACTIVE/ {print $2}' > \ /home/user/running_instances && for i in `cat /home/user/running_instances`; do nova stop $i ; done
Use SSH to connect to the Compute host.
Confirm all instances are down:
# virsh list --all
Shut down the Compute host:
# shutdown -h now
Once the Compute host comes back online, confirm everything is in working order and start the instances on the host. For example:
# cat /home/user/running_instances # do nova start $instance done
Enable the
nova-compute
service in the environment:# nova service-enable HOSTNAME nova-compute
Shutting down the Block Storage host¶
If a LVM backed Block Storage host needs to be shut down:
Disable the
cinder-volume
service:# cinder service-list --host CINDER SERVICE NAME INCLUDING @BACKEND # cinder service-disable CINDER SERVICE NAME INCLUDING @BACKEND \ cinder-volume --reason 'RAM maintenance'
List all instances with Block Storage volumes attached:
# mysql cinder -BNe 'select instance_uuid from volumes where deleted=0 '\ 'and host like "%<cinder host>%"' | tee /home/user/running_instances
Shut down the instances:
# cat /home/user/running_instances | xargs -n1 nova stop
Verify the instances are shutdown:
# cat /home/user/running_instances | xargs -n1 nova show | fgrep vm_state
Shut down the Block Storage host:
# shutdown -h now
Replace the failed hardware and validate the new hardware is functioning.
Enable the
cinder-volume
service:# cinder service-enable CINDER SERVICE NAME INCLUDING @BACKEND cinder-volume
Verify the services on the host are reconnected to the environment:
# cinder service-list --host CINDER SERVICE NAME INCLUDING @BACKEND
Start your instances and confirm all of the instances are started:
# cat /home/user/running_instances | xargs -n1 nova start # cat /home/user/running_instances | xargs -n1 nova show | fgrep vm_state
Destroying Containers¶
To destroy a container, execute the following:
# cd /opt/openstack-ansible/playbooks # openstack-ansible lxc-containers-destroy --limit localhost,<container name|container group>Note
You will be asked two questions:
Are you sure you want to destroy the LXC containers? Are you sure you want to destroy the LXC container data?
The first will just remove the container but leave the data in the bind mounts and logs. The second will remove the data in the bind mounts and logs too.
Warning
If you remove the containers and data for the entire galera_server container group you will lose all your databases! Also, if you destroy the first container in many host groups you will lose other important items like certificates, keys, etc. Be sure that you understand what you’re doing when using this tool.
To create the containers again, execute the following:
# cd /opt/openstack-ansible/playbooks # openstack-ansible lxc-containers-create --limit localhost,lxc_hosts,<container name|container group>
The lxc_hosts host group must be included as the playbook and roles executed require the use of facts from the hosts.
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Accessibility for multi-region Object Storage¶
In multi-region Object Storage utilizing separate database backends, objects
are retrievable from an alternate location if the default_project_id
for a user in the keystone database is the same across each database
backend.
Important
It is recommended to perform the following steps before a failure occurs to avoid having to dump and restore the database.
If a failure does occur, follow these steps to restore the database from the Primary (failed) Region:
Record the Primary Region output of the
default_project_id
for the specified user from the user table in the keystone database:Note
The user is
admin
in this example.# mysql -e "SELECT default_project_id from keystone.user WHERE \ name='admin';" +----------------------------------+ | default_project_id | +----------------------------------+ | 76ef6df109744a03b64ffaad2a7cf504 | +-----------------—————————————————+
Record the Secondary Region output of the
default_project_id
for the specified user from the user table in the keystone database:# mysql -e "SELECT default_project_id from keystone.user WHERE \ name='admin';" +----------------------------------+ | default_project_id | +----------------------------------+ | 69c46f8ad1cf4a058aa76640985c | +----------------------------------+
In the Secondary Region, update the references to the
project_id
to match the ID from the Primary Region:# export PRIMARY_REGION_TENANT_ID="76ef6df109744a03b64ffaad2a7cf504" # export SECONDARY_REGION_TENANT_ID="69c46f8ad1cf4a058aa76640985c" # mysql -e "UPDATE keystone.assignment set \ target_id='${PRIMARY_REGION_TENANT_ID}' \ WHERE target_id='${SECONDARY_REGION_TENANT_ID}';" # mysql -e "UPDATE keystone.user set \ default_project_id='${PRIMARY_REGION_TENANT_ID}' WHERE \ default_project_id='${SECONDARY_REGION_TENANT_ID}';" # mysql -e "UPDATE keystone.project set \ id='${PRIMARY_REGION_TENANT_ID}' WHERE \ id='${SECONDARY_REGION_TENANT_ID}';"
The user in the Secondary Region now has access to objects PUT in the Primary Region. The Secondary Region can PUT objects accessible by the user in the Primary Region.