Multihost deployments with Kubeinit

Until now there was possible to deploy Kubeinit in a single host configuration, this means to deploy all the guest VMs in the same hypervisor. Now, we can decouple the deployment architecture in multiple hosts.

TL;DR;

This post will show how to adjust the inventory files to deploy Kubeinit in multiple hosts.

Network architecture

From the official docs, OVN (Open Virtual Network) is a series of daemons for the Open vSwitch that translate virtual network configurations into OpenFlow. OVN is licensed under the open source Apache 2 license.

OVN provides a higher-layer of abstraction than Open vSwitch, working with logical routers and logical switches, rather than flows. OVN is intended to be used by cloud management software (CMS).

Open vSwitch is a free and open source multi-layer software switch, which is used to manage the traffic between virtual machines and physical or logical networks.

The following is the current network architecture of a Kubeinit deployment.

Adjusting the inventory files

To deploy Kubeinit in multiple hosts the only changes that needs to be made are in the inventory

In this case by default there is only one hypervisor enabled (nyctea).

[hypervisor_nodes]
hypervisor-01 ansible_host=nyctea
# hypervisor-02 ansible_host=tyto
# hypervisor-03 ansible_host=strix
# hypervisor-04 ansible_host=otus

The only action that needs to be taken is uncomment the lines to enable the extra hosts required.

The next step is to determine where to deploy each guest. In this example all guests are deployed to hypervisor-01, make the adjustments as required.

[okd_master_nodes]
okd-master-01 ansible_host=10.0.0.1 mac=52:54:00:34:84:26 interfaceid=47f2be09-9cde-49d5-bc7b-76189dfcb8a9 target=hypervisor-01 type=virtual
okd-master-02 ansible_host=10.0.0.2 mac=52:54:00:53:75:61 interfaceid=fb2028cf-dfb9-4d17-827d-3fae36cb3e98 target=hypervisor-01 type=virtual
okd-master-03 ansible_host=10.0.0.3 mac=52:54:00:96:67:20 interfaceid=d43b705e-86ce-4955-bbf4-3888210af82e target=hypervisor-01 type=virtual

For example, let’s deploy each master node in a different hypervisor:

[okd_master_nodes]
okd-master-01 ansible_host=10.0.0.1 mac=52:54:00:34:84:26 interfaceid=47f2be09-9cde-49d5-bc7b-76189dfcb8a9 target=hypervisor-01 type=virtual
okd-master-02 ansible_host=10.0.0.2 mac=52:54:00:53:75:61 interfaceid=fb2028cf-dfb9-4d17-827d-3fae36cb3e98 target=hypervisor-02 type=virtual
okd-master-03 ansible_host=10.0.0.3 mac=52:54:00:96:67:20 interfaceid=d43b705e-86ce-4955-bbf4-3888210af82e target=hypervisor-03 type=virtual

Now, okd-master-01 will be deployed to hypervisor-01, okd-master-02 will be deployed to hypervisor-02, and okd-master-03 will be deployed to hypervisor-03.

Requirements

To deploy Kubeinit in multiple hypervisors, the only requirement is to have passwordless root access to the hosts from the machine executing ansible-playbook.

Deploying

The deployment procedure is the same as it is for all the other Kubernetes distributions that can be deployed with KubeInit.

Please follow the usage documentation to understand the system’s requirements and the required host supported Linux distributions.

# Choose the distro
distro=okd

# Run the deployment command
git clone https://github.com/kubeinit/kubeinit.git
cd kubeinit
ansible-playbook \
    --user root \
    -v -i ./hosts/$distro/inventory \
    --become \
    --become-user root \
    ./playbooks/$distro.yml

Conclusions

Been able to decouple the cluster across multiple hosts allows to scale and deploy production ready environments, for different use cases. The overlay network deployed with OVN across the hosts provides a simple abstraction layer to communicate all the guests in the cluster.

Special thanks to @dalvarez and @dmellado for their help and insights.

The end

If you like this post, please try the code, raise issues, and ask for more details, features or anything that you feel interested in. Also it would be awesome if you become a stargazer to catch up updates and new features.

This is the main project repository.

Happy KubeIniting!


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