Awesome
Kubeadm Boostrapper with Terraform for OpenStack
This package enhances the data-8 kubeadm bootstrap process by brininging in Terraform to provision the network, hosts, and storage for a kubernetes cluster in OpenStack. It is mostly based on the brilliantly simple article by Andre Zonca of San Diego Supercomputer Center: Deploy scalable Jupyterhub with Kubernetes on Jetstream
How to Build a Cluster
Check out a copy of this repo and cd into the top directory.
Configure variables
You will need to set some of the variables found in variables.tf. The best
way to do this is to create a .tfvars file in the configs directory. This
directory is in .gitignore to make this easy. Entries in .tfvars files
are just name = "value"
Most of the variables should be obvious, but here is a summary with some detail on the more specific value domains.
| Variable | Description |
|---|---|
| env_name | Root name for this cluster. Will be used to name nodes and networks |
| pubkey | Path to a public key file which will be used to generate the key pair |
| privkey | Path to the corresponding private key file which will be used to access the hosts |
| master_flavor | Name of the Openstack instance flavor to use for the master node |
| image | Name of the OS image to be used to initialize master nodes. So far, this has been tested on Ubuntu 16 |
| worker_flavor | Name of the Openstack instance flavor to use for the worker nodes |
| storage_flavor | Name of the Openstack instance flavor to use for the storage nodes |
| external_network_id | ID of the network that has the gateway to the internet |
| pool_name | The name of the pool from which the floating IP belongs to (usually the external network's name) |
| availability_zone | Name of the Openstack availability zone where the hosts should be provisioned |
| worker_count | How many workers to provision |
| worker_ips_count | How many of the workers should be assigned an external IP address? |
| docker_volume_size | All nodes will have external block storage attached to use as the docker storage base (/var/lib/docker). Specify the size for these volumes in GBytes |
| storage_node_count | You can optionally provision nodes to host shared storage. 0 => no PVC support, 1 => NFS-backed PVC, 2+ => GlusterFS-backed PVCs see below |
| storage_node_volume_size | Specify the size of the storage attached to each storage node. Expressed in GBytes |
| pod_network_type | Choose the type of overlay network to use in Kubernetes. Supported options: flannel (default), weave |
| dns_nameservers | A list of IP addresses of DNS name servers available to the new subnet |
Initialize Terraform
This recipe uses Terraform to provision the network, host, and execute the steps to set up your cluster. You will need to install terraform on your local machine.
Terraform uses a plug-in architecture. You will need to instruct it to download and install the plugins used in this setup.
In the root directory of this repo execute the following command:
% terraform init
Set your Openstack Credentials
Terraform makes use of the Openstack environment variables set by the script that you can download from your Openstack portal. Download this file and execute the script. It will prompt you for your password.
Install jq
The step that obtains the join token for the workers to connect to the
kubernetes master requires the jq JSON processor. Please insure that it is
installed on the host where you are executing the terraform command.
Build the Cluster
Now comes the easy part. To build your kubernetes cluster just issue this command in the root folder of this repo:
% terraform apply -var-file="configs/<<your .tfvars file>>"
Using the Cluster
You now have a running cluster with the helm tiller
installed. To interact with it, you will need to log into your master node and
use the kubectl commands from there.
Extneral IP addresses
The master node, as well as the specified number of worker nodes will have
external IP addresses assigned. For your convenience, these nodes are all
labeled external_ip=true.
NFS Provisioner
If you configured a single storage node, it will be provisioned to run the NFS Provisioner. This will run a lightweight NFS server in your Kubernetes cluster for persistent volume claim support.
GlusterFS Provisioner
If you configured 2 or more storage nodes, they will be provisioned to run the GlusterFS Simple Provisioner. This will run a distributed, scalable GlusterFS cluster in your Kubernetes cluster for persistent volume claim support.
NOTE: Many (if not all) GlusterFS volume configurations will require an even
number of storage nodes. We do not support odd-numbered values > 2 for
storage_node_count.
Pod Network Type
Use this setting to change the type of overlay network that will be deployed for your pods to communicate with one another.
Supported options:
flannel(default): Default network support for basic pod-to-pod communicationweave: Provides additional security for creating NetworkPolicy resources to restrict Ingress / Egress between pods
Resizing the cluster
Terraform makes this easy. Just adjust the values for the number of worker nodes and reissue the
% terraform apply
command. Terraform will figure out what needs to change and run exactly the required steps.
If you reduce the number of worker nodes it will remove them from the cluster before deleting the underlying compute instance.
You can expand storage by adding new storage hosts. I don't think it will work to try to reduce the number of storage nodes.
Destroying the Cluster
If you want to release the resources allocated to your cluster you can destroy the cluster with the terraform command:
% terraform destroy