9bfb1c5faf
* Document worker pools `node_labels` variable to set the initial node labels for a homogeneous set of workers * Document `worker_node_labels` convenience variable to set the initial node labels for default worker nodes
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Azure
!!! danger Typhoon for Azure is alpha. For production, use AWS, Google Cloud, or bare-metal. As Azure matures, check errata for known shortcomings.
In this tutorial, we'll create a Kubernetes v1.16.0 cluster on Azure with Container Linux.
We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create a resource group, virtual network, subnets, security groups, controller availability set, worker scale set, load balancer, and TLS assets.
Controller hosts are provisioned to run an etcd-member peer and a kubelet service. Worker hosts run a kubelet service. Controller nodes run kube-apiserver, kube-scheduler, kube-controller-manager, and coredns, while kube-proxy and calico (or flannel) run on every node. A generated kubeconfig provides kubectl access to the cluster.
Requirements
- Azure account
- Azure DNS Zone (registered Domain Name or delegated subdomain)
- Terraform v0.12.x and terraform-provider-ct installed locally
Terraform Setup
Install Terraform v0.12.x on your system.
$ terraform version
Terraform v0.12.7
Add the terraform-provider-ct plugin binary for your system to ~/.terraform.d/plugins/, noting the final name.
wget https://github.com/poseidon/terraform-provider-ct/releases/download/v0.4.0/terraform-provider-ct-v0.4.0-linux-amd64.tar.gz
tar xzf terraform-provider-ct-v0.4.0-linux-amd64.tar.gz
mv terraform-provider-ct-v0.4.0-linux-amd64/terraform-provider-ct ~/.terraform.d/plugins/terraform-provider-ct_v0.4.0
Read concepts to learn about Terraform, modules, and organizing resources. Change to your infrastructure repository (e.g. infra).
cd infra/clusters
Provider
Install the Azure az command line tool to authenticate with Azure.
az login
Configure the Azure provider in a providers.tf file.
provider "azurerm" {
version = "1.34.0"
}
provider "ct" {
version = "0.4.0"
}
Additional configuration options are described in the azurerm provider docs.
Cluster
Define a Kubernetes cluster using the module azure/container-linux/kubernetes.
module "ramius" {
source = "git::https://github.com/poseidon/typhoon//azure/container-linux/kubernetes?ref=v1.16.0"
# Azure
cluster_name = "ramius"
region = "centralus"
dns_zone = "azure.example.com"
dns_zone_group = "example-group"
# configuration
ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
asset_dir = "/home/user/.secrets/clusters/ramius"
# optional
worker_count = 2
host_cidr = "10.0.0.0/20"
}
Reference the variables docs or the variables.tf source.
ssh-agent
Initial bootstrapping requires bootstrap.service be started on one controller node. Terraform uses ssh-agent to automate this step. Add your SSH private key to ssh-agent.
ssh-add ~/.ssh/id_rsa
ssh-add -L
Apply
Initialize the config directory if this is the first use with Terraform.
terraform init
Plan the resources to be created.
$ terraform plan
Plan: 86 to add, 0 to change, 0 to destroy.
Apply the changes to create the cluster.
$ terraform apply
...
module.azure-ramius.null_resource.bootstrap: Still creating... (6m50s elapsed)
module.azure-ramius.null_resource.bootstrap: Still creating... (7m0s elapsed)
module.azure-ramius.null_resource.bootstrap: Creation complete after 7m8s (ID: 3961816482286168143)
Apply complete! Resources: 86 added, 0 changed, 0 destroyed.
In 4-8 minutes, the Kubernetes cluster will be ready.
Verify
Install kubectl on your system. Use the generated kubeconfig credentials to access the Kubernetes cluster and list nodes.
$ export KUBECONFIG=/home/user/.secrets/clusters/ramius/auth/kubeconfig
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ramius-controller-0 Ready <none> 24m v1.16.0
ramius-worker-000001 Ready <none> 25m v1.16.0
ramius-worker-000002 Ready <none> 24m v1.16.0
List the pods.
$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-7c6fbb4f4b-b6qzx 1/1 Running 0 26m
kube-system coredns-7c6fbb4f4b-j2k3d 1/1 Running 0 26m
kube-system flannel-bwf24 2/2 Running 0 26m
kube-system flannel-ks5qb 2/2 Running 0 26m
kube-system flannel-tq2wg 2/2 Running 0 26m
kube-system kube-apiserver-ramius-controller-0 1/1 Running 0 26m
kube-system kube-controller-manager-ramius-controller-0 1/1 Running 0 26m
kube-system kube-proxy-j4vpq 1/1 Running 0 26m
kube-system kube-proxy-jxr5d 1/1 Running 0 26m
kube-system kube-proxy-lbdw5 1/1 Running 0 26m
kube-system kube-scheduler-ramius-controller-0 1/1 Running 0 26m
Going Further
Learn about maintenance and addons.
!!! note
On Container Linux clusters, install the CLUO addon to coordinate reboots and drains when nodes auto-update. Otherwise, updates may not be applied until the next reboot.
Variables
Check the variables.tf source.
Required
| Name | Description | Example |
|---|---|---|
| cluster_name | Unique cluster name (prepended to dns_zone) | "ramius" |
| region | Azure region | "centralus" |
| dns_zone | Azure DNS zone | "azure.example.com" |
| dns_zone_group | Resource group where the Azure DNS zone resides | "global" |
| ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3NZ..." |
| asset_dir | Path to a directory where generated assets should be placed (contains secrets) | "/home/user/.secrets/clusters/ramius" |
!!! tip
Regions are shown in docs or with az account list-locations --output table.
DNS Zone
Clusters create a DNS A record ${cluster_name}.${dns_zone} to resolve a load balancer backed by controller instances. This FQDN is used by workers and kubectl to access the apiserver(s). In this example, the cluster's apiserver would be accessible at ramius.azure.example.com.
You'll need a registered domain name or delegated subdomain on Azure DNS. You can set this up once and create many clusters with unique names.
# Azure resource group for DNS zone
resource "azurerm_resource_group" "global" {
name = "global"
location = "centralus"
}
# DNS zone for clusters
resource "azurerm_dns_zone" "clusters" {
resource_group_name = "${azurerm_resource_group.global.name}"
name = "azure.example.com"
zone_type = "Public"
}
Reference the DNS zone with "${azurerm_dns_zone.clusters.name}" and its resource group with "${azurerm_resource_group.global.name}".
!!! tip "" If you have an existing domain name with a zone file elsewhere, just delegate a subdomain that can be managed on Azure DNS (e.g. azure.mydomain.com) and update nameservers.
Optional
| Name | Description | Default | Example |
|---|---|---|---|
| controller_count | Number of controllers (i.e. masters) | 1 | 1 |
| worker_count | Number of workers | 1 | 3 |
| controller_type | Machine type for controllers | "Standard_DS1_v2" | See below |
| worker_type | Machine type for workers | "Standard_F1" | See below |
| os_image | Channel for a Container Linux derivative | coreos-stable | coreos-stable, coreos-beta, coreos-alpha |
| disk_size | Size of the disk in GB | "40" | "100" |
| worker_node_labels | List of initial worker node labels | [] | ["worker-pool=default"] |
| worker_priority | Set priority to Low to use reduced cost surplus capacity, with the tradeoff that instances can be deallocated at any time | Regular | Low |
| controller_clc_snippets | Controller Container Linux Config snippets | [] | example |
| worker_clc_snippets | Worker Container Linux Config snippets | [] | example |
| networking | Choice of networking provider | "flannel" | "flannel" or "calico" (experimental) |
| host_cidr | CIDR IPv4 range to assign to instances | "10.0.0.0/16" | "10.0.0.0/20" |
| pod_cidr | CIDR IPv4 range to assign to Kubernetes pods | "10.2.0.0/16" | "10.22.0.0/16" |
| service_cidr | CIDR IPv4 range to assign to Kubernetes services | "10.3.0.0/16" | "10.3.0.0/24" |
| cluster_domain_suffix | FQDN suffix for Kubernetes services answered by coredns. | "cluster.local" | "k8s.example.com" |
Check the list of valid machine types and their specs. Use az vm list-skus to get the identifier.
!!! warning
Unlike AWS and GCP, Azure requires its virtual networks to have non-overlapping IPv4 CIDRs (yeah, go figure). Instead of each cluster just using 10.0.0.0/16 for instances, each Azure cluster's host_cidr must be non-overlapping (e.g. 10.0.0.0/20 for the 1st cluster, 10.0.16.0/20 for the 2nd cluster, etc).
!!! warning
Do not choose a controller_type smaller than Standard_DS1_v2. Smaller instances are not sufficient for running a controller.
Low Priority
Add worker_priority=Low to use Low Priority workers that run on Azure's surplus capacity at lower cost, but with the tradeoff that they can be deallocated at random. Low priority VMs are Azure's analog to AWS spot instances or GCP premptible instances.