An Atomic cluster with Heat

These Heat templates will deploy a cluster of Atomic hosts.

Prerequisities

OpenStack version Juno or later with the Heat and Neutron services running
Atomic Host cloud image (we leverage cloud-init) loaded in Glance
An SSH keypair loaded to Nova
A (Neutron) network with a pool of floating IP addresses available

Usage

Deployment

At the very least you have to need to specify your Atomic image, SSH keypair, external network and the number of hosts to deploy:

heat stack-create my-atomic-cluster -f atomic-cluster.yaml \
    -P server_image=Fedora-Cloud-Atomic-22 \
    -P ssh_key_name=default \
    -P external_network=external \
    -P node_count=3

Inventory

You can run heat output-show my-atomic-cluster host_ips to get the list of IP address assigned to the hosts:

[
  "10.23.68.158",
  "10.23.68.159",
  "10.23.68.160"
]

Note that the name of the SSH user differs for various cloud images. It's fedora for Fedora images and cloud-user for the latest CentOS and RHEL.

Custom DNS Servers

If you want to add your own (perhaps internal) DNS servers, pass into the dns_nameserver parameter separated by comas:

heat stack-create my-atomic-cluster ... -P dns_nameserver=10.16.5.22,10.37.5.18

RHN Registration

By specifying both rhn_username and rhn_password, your RHEL hosts will be automatically registered (with subscription-manager register --username=... --password=... --auto-attach).

Scaling

There is no autoscaling set up in the templates, but you can change the cluster capacity manually by signalling the scale_up or scale_down resources:

heat resource-signal my-atomic-cluster scale_up
heat resource-signal my-atomic-cluster scale_down

These will add or remove a single host.

You can also do a stack update and change the node_count parameter:

heat stack-update my-atomic-cluster -f atomic-cluster.yaml \
    -P server_image=Fedora-Cloud-Atomic-22 \
    -P ssh_key_name=default \
    -P external_network=external \
    -P node_count=4

Copyright

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

razorinc/heat-atomic