Using A Manifest to Manage kops Clusters

Using A Manifest to Manage kops Clusters
Exporting a Cluster
Further References
Instance Groups

Background

Because of the above statement kops includes an API which provides a feature for users to utilize YAML or JSON manifests for managing their kops created Kubernetes installations. In the same way that you can use a YAML manifest to deploy a Job, you can deploy and manage a kops Kubernetes instance with a manifest. All of these values are also usable via the interactive editor with kops edit.

You can see all the options that are currently supported in Kops or more prettily here

The following is a list of the benefits of using a file to manage instances.

Capability to access API values that are not accessible via the command line such as setting the max price for spot instances.
Create, replace, update, and delete clusters without entering an interactive editor. This feature is helpful when automating cluster creation.
Ability to check-in files to source control that represents an installation.
Run commands such as kops delete -f mycluster.yaml.

At this time you must run kops create cluster and then export the YAML from the state store. We plan in the future to have the capability to generate kops YAML via the command line. The following is an example of creating a cluster and exporting the YAML.

The above command exports a YAML document which contains the definition of the cluster, kind: Cluster, and the definitions of the instance groups, kind: InstanceGroup.

NOTE: If you run kops get cluster $NAME -o yaml > $NAME.yaml, you will only get a cluster spec. Use the command above (kops get $NAME ...)for both the cluster spec and all instance groups.

apiVersion: kops/v1alpha2
kind: Cluster
metadata:
  creationTimestamp: 2017-05-04T23:21:47Z
  name: k8s.example.com
spec:
  api:
    loadBalancer:
      type: Public
  authorization:
    alwaysAllow: {}
  channel: stable
  cloudProvider: aws
  configBase: s3://example-state-store/k8s.example.com
  etcdClusters:
  - etcdMembers:
    - instanceGroup: master-us-east-2d
      name: a
    - instanceGroup: master-us-east-2b
      name: b
    - instanceGroup: master-us-east-2c
      name: c
    name: main
  - etcdMembers:
    - instanceGroup: master-us-east-2d
      name: a
    - instanceGroup: master-us-east-2b
      name: b
    - instanceGroup: master-us-east-2c
      name: c
    name: events
  kubernetesApiAccess:
  - 0.0.0.0/0
  kubernetesVersion: 1.6.6
  masterPublicName: api.k8s.example.com
  networkCIDR: 172.20.0.0/16
  networkID: vpc-6335dd1a
  networking:
    weave: {}
  nonMasqueradeCIDR: 100.64.0.0/10
  sshAccess:
  - 0.0.0.0/0
  subnets:
  - cidr: 172.20.32.0/19
    name: us-east-2d
    type: Private
    zone: us-east-2d
  - cidr: 172.20.64.0/19
    name: us-east-2b
    type: Private
    zone: us-east-2b
  - cidr: 172.20.96.0/19
    type: Private
    zone: us-east-2c
  - cidr: 172.20.0.0/22
    name: utility-us-east-2d
    type: Utility
  - cidr: 172.20.4.0/22
    name: utility-us-east-2b
    type: Utility
    zone: us-east-2b
  - cidr: 172.20.8.0/22
    name: utility-us-east-2c
    type: Utility
    zone: us-east-2c
  topology:
    bastion:
      bastionPublicName: bastion.k8s.example.com
    dns:
      type: Public
    masters: private
    nodes: private
---
apiVersion: kops/v1alpha2
kind: InstanceGroup
metadata:
  creationTimestamp: 2017-05-04T23:21:48Z
  labels:
    kops.k8s.io/cluster: k8s.example.com
  name: bastions
spec:
  image: kope.io/k8s-1.6-debian-jessie-amd64-hvm-ebs-2017-05-02
  machineType: t2.micro
  maxSize: 1
  minSize: 1
  role: Bastion
  subnets:
  - utility-us-east-2d
  - utility-us-east-2b
  - utility-us-east-2c
---
apiVersion: kops/v1alpha2
kind: InstanceGroup
metadata:
  creationTimestamp: 2017-05-04T23:21:47Z
  labels:
    kops.k8s.io/cluster: k8s.example.com
  name: master-us-east-2d
spec:
  image: kope.io/k8s-1.6-debian-jessie-amd64-hvm-ebs-2017-05-02
  machineType: m4.large
  maxSize: 1
  minSize: 1
  role: Master
  subnets:
  - us-east-2d
---
apiVersion: kops/v1alpha2
kind: InstanceGroup
metadata:
  creationTimestamp: 2017-05-04T23:21:47Z
  labels:
    kops.k8s.io/cluster: k8s.example.com
  name: master-us-east-2b
spec:
  machineType: m4.large
  maxSize: 1
  role: Master
  subnets:
  - us-east-2b
---
apiVersion: kops/v1alpha2
kind: InstanceGroup
metadata:
  creationTimestamp: 2017-05-04T23:21:48Z
  labels:
    kops.k8s.io/cluster: k8s.example.com
  name: master-us-east-2c
spec:
  image: kope.io/k8s-1.6-debian-jessie-amd64-hvm-ebs-2017-05-02
  machineType: m4.large
  maxSize: 1
  minSize: 1
  role: Master
  subnets:
  - us-east-2c
---
apiVersion: kops/v1alpha2
kind: InstanceGroup
metadata:
  creationTimestamp: 2017-05-04T23:21:48Z
  labels:
    kops.k8s.io/cluster: k8s.example.com
  name: nodes
spec:
  image: kope.io/k8s-1.6-debian-jessie-amd64-hvm-ebs-2017-05-02
  machineType: m4.xlarge
  maxSize: 3
  minSize: 3
  role: Node
  subnets:
  - us-east-2d
  - us-east-2b
  - us-east-2c

YAML Examples

With the above YAML file, a user can add configurations that are not available via the command line. For instance, you can add a maxPrice value to a new instance group and use spot instances. Also add node and cloud labels for the new instance group.

This configuration will create an autoscale group that will include 42 m4.10xlarge nodes running as spot instances with custom labels.

To create the cluster execute:

kops create -f $NAME.yaml
kops create secret --name $NAME sshpublickey admin -i ~/.ssh/id_rsa.pub
kops update cluster $NAME --yes
kops rolling-update cluster $NAME --yes

Please refer to the rolling-update documentation.

Update the cluster spec YAML file, and to update the cluster run:

Please refer to the rolling-update .

kops implements a full API that defines the various elements in the YAML file exported above. Two top level components exist; ClusterSpec and InstanceGroup.

apiVersion: kops/v1alpha2
kind: Cluster
metadata:
  creationTimestamp: 2017-05-04T23:21:47Z
  name: k8s.example.com
spec:
  api:

The ClusterSpec allows a user to set configurations for such values as Docker log driver, Kubernetes API server log level, VPC for reusing a VPC (NetworkID), and the Kubernetes version.

More information about some of the elements in the ClusterSpec is available in the following:

Cluster Spec document which outlines some of the values in the Cluster Specification.
GPU setup
- adding additional IAM roles.
Labels

To access the full configuration that a kops installation is running execute:

This command prints the entire YAML configuration. But do not use the full document, you may experience strange and unique unwanted behaviors.

Instance Groups

apiVersion: kops/v1alpha2
kind: InstanceGroup
metadata:
  creationTimestamp: 2017-05-04T23:21:48Z
  name: foo
spec:

Full documentation is accessible via .

Instance Groups map to Auto Scaling Groups in AWS, and Instance Groups in GCE. They are an API level description of a group of compute instances used as Masters or Nodes.

More documentation is available in the Instance Group document.

Closing Thoughts

If you do not need to define or customize a value, let kops set that value. Setting too many values prevents kops from doing its job in setting up the cluster and you may end up with strange bugs.
If you end up with strange bugs, try letting kops do more.
Be cautious, take care, and test outside of production!

If you need to run a custom version of Kubernetes Controller Manager, set kubeControllerManager.image and update your cluster. This is the beauty of using a manifest for your cluster!

Using Manifests and Customizing via the API

Using A Manifest to Manage kops Clusters

Background

YAML Examples

Instance Groups

Closing Thoughts