ocp4_machineset_config

OpenShift 4 MachineSet management to implement custom machinesets such as to create dedicated compute and infra nodes.

This Ansible role will query the cluster for the default worker machinesets provisioned by the installer and then manage custom machinesets based on the discovered worker configuration information.

Note

As OpenShift 4 is a fast moving target this Ansible role may become obsolete at any time. In particular we hope that the standard OpenShift installer or a standard OpenShift 4 operator will manage custom machinesets such as to render this Ansible role redundant.

Example Playbooks

Example creating machinesets based on default worker machinesets:

- hosts: localhost
  connection: local
  gather_facts: no
  roles:
  - role: ocp4_machineset_config
  vars:
    ocp4_machineset_config_disable_default_worker_machinesets: true
    ocp4_machineset_config_groups:
    - name: compute
      autoscale: true
      role: compute
      total_replicas_min: 3
      total_replicas_max: 30
      aws_instance_type: m4.large
      aws_root_volume_size: 80
    - name: infra
      role: infra
      total_replicas: 2
      aws_instance_type: m4.large

Example creating machinesets from scratch:

---
- hosts: localhost
  connection: local
  gather_facts: no
  roles:
  - role: ocp4_machineset_config
  vars:
    ocp4_machineset_config_cloud_provider: aws
    ocp4_machineset_config_cluster_infra_id: "{{ lookup('env', 'INFRA_ID') }}"
    ocp4_machineset_config_aws_iam_instance_profile_id: "{{ lookup('env', 'WorkerInstanceProfile') }}"
    ocp4_machineset_config_aws_security_group_search_key: group-id
    ocp4_machineset_config_aws_security_group_search_value: "{{ lookup('env', 'WorkerSecurityGroupId') }}"
    ocp4_machineset_config_aws_availability_zone_data: >-
      {{ lookup('pipe', 'aws ec2 describe-subnets --region=$REGION --subnet-ids ${PrivateSubnetIds//,/ }') }}
    ocp4_machineset_config_groups:
    - name: compute
      aws_instance_type: m4.large
      aws_root_volume_size: 80
      autoscale: true
      role: compute
      total_replicas_min: 1
      total_replicas_max: 30
    - name: infra
      aws_instance_type: m4.large
      role: infra
      total_replicas: 1

Installation

ansible-galaxy install \
https://github.com/gnuthought/ansible-role-ocp4_machineset_config/archive/master.tar.gz#/ocp4_machineset_config

Configuration

Table 1. Top level configuration variables

Variable	Default	Description
ocp4_machineset_config_cloud_provider	(detect from default worker machinesets)	Cloud provider, currently only "aws" is supported.
ocp4_machineset_config_cluster_infra_id	(detect from default worker machinesets)	Infrastructure tag and label used to identify cluster.
ocp4_machineset_config_domain	"ocp4-machineset-config.gnuthought.com"	Domain used for custom group label.
ocp4_machineset_config_group_label	"{{ ocp4_machineset_config_domain }}/machineset-group"	Label applied to machinesets to identify machinesets managed by this role.
ocp4_machineset_config_groups	[]	Listed of machineset groups, described below.
ocp4_machineset_config_disable_default_worker_machinesets	false	Boolean to indicate if default worker machinesets should be scaled to zero.
openshift_cluster_autoscaler_spec	{"scaleDown:{"enabled": true}}	Value for spec section of ClusterAutoscaler definition, applied if any machineset enables autoscaling.

Table 2. AWS configuration variables

Variable	Default	Description
ocp4_machineset_config_aws_availability_zone_data	None	JSON output of aws ec2 describe-subnets --region=$REGION --subnet-ids …​
ocp4_machineset_config_aws_availability_zones	(detect from default worker machinesets)	Availability zones for worker machinesets
ocp4_machineset_config_aws_iam_instance_profile_id	(detect from default worker machinesets)	AWS IAM instance profile ID
ocp4_machineset_config_aws_instance_type	"m4.large"	Default AWS instance type.
ocp4_machineset_config_aws_root_volume_size	120	AWS root volume size default in GB
ocp4_machineset_config_aws_security_group_search_key	(detect from default worker machinesets)	Key used to find security group
ocp4_machineset_config_aws_security_group_search_value	(detect from default worker machinesets)	Value used to find security group
ocp4_machineset_config_aws_tags	Cluster infra id label	Tags applied to AWS ec2 instances

Table 3. ocp4_machineset_config_groups item values

Variable	Default	Description
name	(required)	Name for machineset config group
role	(optional)	Value used for default machine and node labels
total_replicas	0	Total number of machineset replicas for non-autoscaling machinesets
autoscale	False	Boolean to indicate if machineautoscaler should be configured for machinesets
total_replicas_min	0	Total minimum number of machineset replicas for non-autoscaling machinesets
total_replicas_max	100	Total maximum number of machineset replicas for non-autoscaling machinesets
aws_instance_type	ocp4_machineset_config_aws_instance_type	Default AWS instance type
aws_root_volume_size	ocp4_machineset_config_aws_root_volume_size	Default root EBS storage disk size