AWS Single Node Openshift/OKD (SingleReplica Topology)

Install a single node replica OpenShift/OKD.

The steps will create every infrastrucure stack to deploy a SNO on the AWS provider.

The infra resources created will be:

VPC and it's subnets on a single AZ
Security Groups
Load Balancers for API (public and private) and Apps
DNS Zones and RRs
Compute resources: Bootstrap and single node control plane

Deployment considerations

The deployment described in this document is introducing a more performant disk layout to avoid disruptions and concurrency between resources on the same disk (by default). The disk layout is when using EC2 instance m6id.xlarge:

Ephemeral disk (local storage) for /var/lib/containers
Dedicated etcd EBS mounted on /var/lib/etcd

$ cat ~/opct/results/opct-sno-aws/sno2-run-lsblk.txt
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
nvme0n1     259:0    0   128G  0 disk 
|-nvme0n1p1 259:4    0     1M  0 part 
|-nvme0n1p2 259:5    0   127M  0 part 
|-nvme0n1p3 259:6    0   384M  0 part /boot
`-nvme0n1p4 259:7    0 127.5G  0 part /sysroot
nvme1n1     259:1    0    32G  0 disk 
`-nvme1n1p1 259:3    0    32G  0 part /var/lib/etcd
nvme2n1     259:2    0 220.7G  0 disk /var/lib/containers

Using this layout we decreased the amount of memory used by monitoring stack (Prometheus), and, consequently the etcd when using a single/shared-disk deployment. The API disruptions decreased drastically, allowing to use smaller instance types with 16GiB of RAM and 4 vCPU.

Steps:

Generate the SNO ignitions
Create the Stacks: Network, IAM, DNS, LB
Create the Compute with ignition

Create the configuration variables

cat <<EOF> ./vars-sno.yaml
provider: aws
cluster_name: sno-aws

config_base_domain: devcluster.openshift.com
config_ssh_key: "$(cat ~/.ssh/id_rsa.pub)"
config_pull_secret_file: ${HOME}/.openshift/pull-secret-latest.json
config_cluster_region: us-east-1

cluster_profile: sno
create_worker: no
destroy_bootstrap: no

config_compute_replicas: 0
config_controlplane_replicas: 1
cert_expected_nodes: 0
config_bootstrapinplace_disk: /dev/nvme0n1

# Choose the instance type for SNO node.
# NOTE: the okd-installer does not support yet the spot
#- m6i.xlarge: ~140/od ~52/spot
#- m6id.xlarge: ~173/od ~52/spot
#- m6idn.xlarge: ~232/od ~52/spot
#- r5d.xlarge: ~210/od ~52/spot
#- r6id.xlarge: ~220/od ~54/spot
#- t4g.xlarge: ~98/od 29/spot
#- m6gd.xlarge: ~131/od ~52/spot
#- r6gd.2xlaarge: ~168/od ~62/spot
controlplane_instance: m6id.xlarge

# Patch manifests to:
# 1) mount ephemeral disk on /var/lib/containers
# 2) mount extra disk for etcd (/var/lib/etcd)
# 3) remove machine api objects
config_patches:
- mc_varlibcontainers
- mc_varlibetcd
- rm-capi-machines

cfg_patch_mc_varlibcontainers:
  device_path: /dev/nvme2n1
  device_name: nvme2n1
  machineconfiguration_roles:
  - master

# TODO: create cfg for patch mc_varlibetcd to receive the disk

EOF

Client

See Install the Clients

Config

Create the installation configuration:

ansible-playbook mtulio.okd_installer.config \
    -e mode=create \
    -e @./vars-sno.yaml

Deploy each stack (optional)

the playbook create_all can be used to deploy all stacks

Network Stack

ansible-playbook mtulio.okd_installer.stack_network \
    -e @./vars-sno.yaml

IAM Stack

ansible-playbook mtulio.okd_installer.stack_iam \
    -e @./vars-sno.yaml

DNS Stack

ansible-playbook mtulio.okd_installer.stack_dns \
    -e @./vars-sno.yaml

Load Balancer Stack

ansible-playbook mtulio.okd_installer.stack_loadbalancer \
    -e @./vars-sno.yaml

Compute Stack: Deploy the bootstrap node
Create the Bootstrap Node

ansible-playbook mtulio.okd_installer.create_node \
    -e @./vars-sno.yaml \
    -e node_role=controlplane

Deploy cluster

Deploy a cluster creating all the resources with a single execution/playbook:

This steps will deploy all the stacks

ansible-playbook mtulio.okd_installer.create_all \
    -e @./vars-sno.yaml

You can check when the bootstrap finished, or the Single Replica node have joined to the cluster:

$ KUBECONFIG=$HOME/.ansible/okd-installer/clusters/opct-sno/auth/kubeconfig oc get nodes
NAME             STATUS   ROLES                               AGE   VERSION
ip-10-0-50-187   Ready    control-plane,master,tests,worker   24m   v1.25.4+77bec7a

The you can destroy the bootstrap node:

Alternatively you can opt to remove the flag destroy_bootstrap to your var file

ansible-playbook mtulio.okd_installer.destroy_bootstrap \
    -e @./vars-sno.yaml

Destroy

ansible-playbook mtulio.okd_installer.destroy_cluster \
    -e @./vars-sno.yaml