Kubernetes kOps Tutorial

Guide to Kubernetes Tools
Chapter 4 Kubernetes kOps Tutorial

Kubernetes provides excellent container orchestration, but setting up a Kubernetes cluster from scratch can be painful. One solution is to use Kubernetes Operations, or kOps.

What is kOps?

kOps, also known as Kubernetes operations, is an open-source project which helps you create, destroy, upgrade, and maintain a highly available, production-grade Kubernetes cluster. Depending on the requirement, kOps can also provision cloud infrastructure.

kOps is mostly used in deploying AWS and GCE Kubernetes clusters. But officially, the tool only supports AWS. Support for other cloud providers (such as DigitalOcean, GCP, and OpenStack) are in the beta stage at the time of writing this article. The developers of this open source project describe it as “kubectl for clusters” on their Github homepage which may be confusing for some but helpful for others. Let’s start by reviewing its benefits.

Benefits of kOps

  • Automates the provisioning of AWS and GCE Kubernetes clusters
  • Deploys highly available Kubernetes masters
  • Supports rolling cluster updates
  • Autocompletion of command in the command line
  • Generates Terraform and CloudFormation configurations
  • Manages cluster add-ons
  • Supports state-sync model for dry-runs and automatic idempotency
  • Creates instance groups to support heterogeneous clusters

How to Install kOps

Use the following steps to install kOps on your Linux machine. In this example, we are using Ubuntu 18.04.

  1. Download kOps from the releases package.
    [email protected]:~$ curl -Lo kOps https://github.com/kubernetes/kOps/releases/download/$(curl -s https://api.github.com/repos/kubernetes/kOps/releases/latest | grep tag_name | cut -d '"' -f 4)/kOps-linux-amd64
    Saving to: ‘kOps-linux-amd64’
    100%[=========================================================================================================================================================================>] 75,924,000  9.34MB/s   in 9.2s   
    2021-02-15 14:29:21 (7.84 MB/s) - ‘kOps-linux-amd64’ saved [75924000/75924000]
    
  2. Give executable permission to the downloaded kOps file and move it to /usr/local/bin/
    [email protected]:~$ sudo chmod +x kOps-linux-amd64 
    [email protected]:~$ sudo mv kOps-linux-amd64 /usr/local/bin/kOps
    
  3. Run the kOps command to verify the installation.
    [email protected]:~$ kOps
    kOps is Kubernetes ops. 
    kOps is the easiest way to get a production grade Kubernetes cluster up and running. We like to think of it as kubectl for clusters. 
    kOps helps you create, destroy, upgrade and maintain production-grade, highly available, Kubernetes clusters from the command line.  AWS (Amazon Web Services) is currently officially supported, with GCE and VMware vSphere in alpha support.
    Usage:
      kOps [command]
    Available Commands:
      completion     Output shell completion code for the given shell (bash or zsh).
      create         Create a resource by command line, filename or stdin.
      delete         Delete clusters,instancegroups, or secrets.
      describe       Describe a resource.
      edit           Edit clusters and other resources.
      export         Export configuration.
      get            Get one or many resources.
      import         Import a cluster.
      replace        Replace cluster resources.
      rolling-update Rolling update a cluster.
      toolbox        Misc infrequently used commands.
      update         Update a cluster.
      upgrade        Upgrade a kubernetes cluster.
      validate       Validate a kOps cluster.
      version        Print the kOps version information.
    Flags:
          --alsologtostderr                  log to standard error as well as files
          --config string                    config file (default is $HOME/.kOps.yaml)
      -h, --help                             help for kOps
          --log_backtrace_at traceLocation   when logging hits line file:N, emit a stack trace (default :0)
          --log_dir string                   If non-empty, write log files in this directory
          --logtostderr                      log to standard error instead of files (default false)
          --name string                      Name of cluster
          --state string                     Location of state storage
          --stderrthreshold severity         logs at or above this threshold go to stderr (default 2)
      -v, --v Level                          log level for V logs
          --vmodule moduleSpec               comma-separated list of pattern=N settings for file-filtered logging
    Use "kOps [command] --help" for more information about a command.
  4. Check the kOps version.
    [email protected]:~$ kOps version
    Version 1.8.0 (git-5099bc5)

The Basics of kOps Commands

Below are the most widely-used kOps commands you should know.

kOps create

This kOps command is used to register a cluster:

kOps create cluster <clustername>

There are many other parameters which you can add in addition to the default command, like zone, region, instance type, and number of nodes.

kOps update

This kOps command is used to update the cluster with the specified cluster specification:

kOps update cluster --name <clustername>

We recommend running this command in preview mode when you need to triangulate your desired output. Run the command with the --yes flag to apply your changes to the cluster.

kOps get

This kOps command is used to list all the clusters.

kOps get clusters

kOps delete

This command deletes a specified cluster from the registry along with all of its cloud resources.

kOps delete cluster --name <clustername>

You can also run this command in preview mode, just like update.

kOps rolling-update

This kOps command is used to update a Kubernetes cluster to match the cloud and kOps specifications.

kOps rolling-update cluster --name <clustername>

You can run this command also in the preview mode just like update.

kOps validate

This command validates if the created cluster is up or not. If the nodes and pods are still in the pending state, the validate command returns that the cluster is not healthy yet.

kOps validate cluster --wait <specified_time>

This command waits and validates the cluster for 10 minutes.

Now that you know the basics of kOps commands, let’s look at how to create a Kubernetes cluster on AWS using kOps.

How to Set Up Kubernetes on AWS using kOps

  1. Install kubectl.
    [email protected]:~$  curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100 38.3M  100 38.3M    0     0  6862k      0  0:00:05  0:00:05 --:--:-- 8127k
  2. Give the executable permission to the downloaded file and move it to /usr/local/bin/
    [email protected]:~$  chmod +x ./kubectl
    [email protected]:~$  sudo mv ./kubectl /usr/local/bin/kubectl
  3. Create an S3 Bucket using the AWS CLI where kOps will save all the cluster's state information. Use LocationConstraint to avoid any error with the region.
    [email protected]:~$ aws s3api create-bucket --bucket my-kOps-bucket-1132 --region us-west-2 --create-bucket-configuration LocationConstraint=us-west-2
    {
        "Location": "http://my-kOps-bucket-1132.s3.amazonaws.com/"
    }
  4. List the aws s3 bucket to see the bucket you have created.
    [email protected]:~$ aws s3 ls
    2021-02-16 17:10:24 my-kOps-bucket-1132
  5. Enable the version for the s3 bucket.
    [email protected]:~$ aws s3api put-bucket-versioning --bucket my-kOps-bucket-1132 --versioning-configuration Status=Enabled
  6. Generate ssh key for which will be used by kOps for cluster login and password generation.
    [email protected]:~$ ssh-keygen
    Generating public/private rsa key pair.
    Enter file in which to save the key (/home/ubuntu/.ssh/id_rsa):
    Enter passphrase (empty for no passphrase):
    Enter same passphrase again:
    Your identification has been saved in /home/ubuntu/.ssh/id_rsa.
    Your public key has been saved in /home/ubuntu/.ssh/id_rsa.pub.
    The key fingerprint is:
    SHA256:fH4JCBXMNRqzk1hmoK+cXmwSFaeBsuGBA5IWMkNuvq0 [email protected]
    The key's randomart image is:
    +---[RSA 2048]----+
    |O=.  .++Xoo      |
    |B++ .. @o* .     |
    |.= =. = =        |
    |o o  o o o       |
    | .  . . S o      |
    |  o. =   o . .   |
    | . .= +   . o    |
    |  .. +     .     |
    | E  .            |
    +----[SHA256]-----+
  7. Expose the cluster name and s3 bucket as environment variables. This is only applicable for the current session. The suffix ‘.k8s.local’ is used because we are not using any pre-configured DNS.
    [email protected]:~$ export kOps_CLUSTER_NAME=kOpsdemo1.k8s.local
    [email protected]:~$ export kOps_STATE_STORE=s3://my-kOps-bucket-1132
  8. Use the kOps create command to create the cluster. Below are the parameters we used:
    --cloud
    tells which cloud provider I am using
    --zones
    is the zone where the cluster instance will get deployed
    --node-count
    is the number of nodes I want in the Kubernetes cluster I am deploying
    --node-size / --master-size
    are the ec2 instance types, I am using the micro instances
    --name
    is the name of the cluster
    [email protected]:~$ kOps create cluster --cloud=aws --zones=eu-central-1a --node-count=1 --node-size=t2.micro --master-size=t2.micro --name=${kOps_CLUSTER_NAME}
    I0216 17:14:49.225238    3547 subnets.go:180] Assigned CIDR 172.20.32.0/19 to subnet eu-central-1a
    I0216 17:14:50.068088    3547 create_cluster.go:717] Using SSH public key: /home/ubuntu/.ssh/id_rsa.pub
    Previewing changes that will be made:
    I0216 17:14:51.332590    3547 apply_cluster.go:465] Gossip DNS: skipping DNS validation
    I0216 17:14:51.392712    3547 executor.go:111] Tasks: 0 done / 83 total; 42 can run
    W0216 17:14:51.792113    3547 vfs_castore.go:604] CA private key was not found
    I0216 17:14:51.938057    3547 executor.go:111] Tasks: 42 done / 83 total; 17 can run
    I0216 17:14:52.436407    3547 executor.go:111] Tasks: 59 done / 83 total; 18 can run
    I0216 17:14:52.822395    3547 executor.go:111] Tasks: 77 done / 83 total; 2 can run
    I0216 17:14:52.823088    3547 executor.go:111] Tasks: 79 done / 83 total; 2 can run
    I0216 17:14:53.406919    3547 executor.go:111] Tasks: 81 done / 83 total; 2 can run
    I0216 17:14:53.842148    3547 executor.go:111] Tasks: 83 done / 83 total; 0 can run
      LaunchTemplate/master-eu-central-1a.masters.kOpsdemo1.k8s.local
            AssociatePublicIP       true
            HTTPPutResponseHopLimit 1
            HTTPTokens              optional
            IAMInstanceProfile      name:masters.kOpsdemo1.k8s.local id:masters.kOpsdemo1.k8s.local
            ImageID                 099720109477/ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-20210119.1
            InstanceType            t2.micro
            RootVolumeSize          64
            RootVolumeType          gp2
            RootVolumeEncryption    false
            RootVolumeKmsKey
            SSHKey                  name:kubernetes.kOpsdemo1.k8s.local-3e:19:92:ca:dd:64:d5:cf:ff:ed:3a:92:0f:40:d4:e8 id:kubernetes.kOpsdemo1.k8s.local-3e:19:92:ca:dd:64:d5:cf:ff:ed:3a:92:0f:40:d4:e8
            SecurityGroups          [name:masters.kOpsdemo1.k8s.local]
            SpotPrice
            Tags                    {k8s.io/cluster-autoscaler/node-template/label/kubernetes.io/role: master, k8s.io/cluster-autoscaler/node-template/label/kOps.k8s.io/instancegroup: master-eu-central-1a, k8s.io/role/master: 1, kOps.k8s.io/instancegroup: master-eu-central-1a, Name: master-eu-central-1a.masters.kOpsdemo1.k8s.local, KubernetesCluster: kOpsdemo1.k8s.local, kubernetes.io/cluster/kOpsdemo1.k8s.local: owned, k8s.io/cluster-autoscaler/node-template/label/node-role.kubernetes.io/master: }
      Subnet/eu-central-1a.kOpsdemo1.k8s.local
            ShortName               eu-central-1a
            VPC                     name:kOpsdemo1.k8s.local
            AvailabilityZone        eu-central-1a
            CIDR                    172.20.32.0/19
            Shared                  false
            Tags                    {KubernetesCluster: kOpsdemo1.k8s.local, kubernetes.io/cluster/kOpsdemo1.k8s.local: owned, SubnetType: Public, kubernetes.io/role/elb: 1, Name: eu-central-1a.kOpsdemo1.k8s.local}
      VPC/kOpsdemo1.k8s.local
            CIDR                    172.20.0.0/16
            EnableDNSHostnames      true
            EnableDNSSupport        true
            Shared                  false
            Tags                    {kubernetes.io/cluster/kOpsdemo1.k8s.local: owned, Name: kOpsdemo1.k8s.local, KubernetesCluster: kOpsdemo1.k8s.local}
      VPCDHCPOptionsAssociation/kOpsdemo1.k8s.local
            VPC                     name:kOpsdemo1.k8s.local
            DHCPOptions             name:kOpsdemo1.k8s.local
    Must specify --yes to apply changes
    Cluster configuration has been created.
    Suggestions:
     * list clusters with: kOps get cluster
     * edit this cluster with: kOps edit cluster kOpsdemo1.k8s.local
     * edit your node instance group: kOps edit ig --name=kOpsdemo1.k8s.local nodes-eu-central-1a
     * edit your master instance group: kOps edit ig --name=kOpsdemo1.k8s.local master-eu-central-1a
    Finally configure your cluster with: kOps update cluster --name kOpsdemo1.k8s.local --yes –admin
    
  9. Verify that the cluster was created.
    [email protected]:~$ kOps get cluster
    NAME                    CLOUD   ZONES
    kOpsdemo1.k8s.local     aws     eu-central-1a
  10. Apply the specified cluster specifications to the cluster.
    [email protected]:~$ kOps update cluster --name kOpsdemo1.k8s.local --yes --admin
    I0216 17:15:24.800767    3556 apply_cluster.go:465] Gossip DNS: skipping DNS validation
    I0216 17:15:25.919282    3556 executor.go:111] Tasks: 0 done / 83 total; 42 can run
    W0216 17:15:26.343336    3556 vfs_castore.go:604] CA private key was not found
    I0216 17:15:26.421652    3556 keypair.go:195] Issuing new certificate: "etcd-clients-ca"
    I0216 17:15:26.450699    3556 keypair.go:195] Issuing new certificate: "etcd-peers-ca-main"
    I0216 17:15:26.470785    3556 keypair.go:195] Issuing new certificate: "etcd-manager-ca-main"
    I0216 17:15:26.531852    3556 keypair.go:195] Issuing new certificate: "etcd-peers-ca-events"
    I0216 17:15:26.551601    3556 keypair.go:195] Issuing new certificate: "apiserver-aggregator-ca"
    I0216 17:15:26.571834    3556 keypair.go:195] Issuing new certificate: "etcd-manager-ca-events"
    I0216 17:15:26.592090    3556 keypair.go:195] Issuing new certificate: "master"
    W0216 17:15:26.652894    3556 vfs_castore.go:604] CA private key was not found
    I0216 17:15:26.653013    3556 keypair.go:195] Issuing new certificate: "ca"
    I0216 17:15:31.344075    3556 executor.go:111] Tasks: 42 done / 83 total; 17 can run
    I0216 17:15:32.306125    3556 executor.go:111] Tasks: 59 done / 83 total; 18 can run
    I0216 17:15:34.189798    3556 executor.go:111] Tasks: 77 done / 83 total; 2 can run
    I0216 17:15:34.190464    3556 executor.go:111] Tasks: 79 done / 83 total; 2 can run
    I0216 17:15:35.738600    3556 executor.go:111] Tasks: 81 done / 83 total; 2 can run
    I0216 17:15:37.810100    3556 executor.go:111] Tasks: 83 done / 83 total; 0 can run
    I0216 17:15:37.904257    3556 update_cluster.go:313] Exporting kubecfg for cluster
    kOps has set your kubectl context to kOpsdemo1.k8s.local
    Cluster is starting.  It should be ready in a few minutes.
    Suggestions:
     * validate cluster: kOps validate cluster --wait 10m
     * list nodes: kubectl get nodes --show-labels
     * ssh to the master: ssh -i ~/.ssh/id_rsa [email protected]
     * the ubuntu user is specific to Ubuntu. If not using Ubuntu please use the appropriate user based on your OS.
     * read about installing addons at: https://kOps.sigs.k8s.io/operations/addons.
    If you immediately check the Kubernetes nodes are running or not, you will get an error. You need to be a little patient and wait for a few minutes (5-10) till the cluster is created.
    [email protected]:~$ kubectl get nodes
    Unable to connect to the server: dial tcp: lookup api-kOpsdemo1-k8s-local-dason2-1001342368.eu-central-1.elb.amazonaws.com on 127.0.0.53:53: no such host
  11. Validate the Cluster.
    [email protected]:~$ kOps validate cluster --wait 10m
    Validating cluster kOpsdemo1.k8s.local
    INSTANCE GROUPS
    NAME                    ROLE    MACHINETYPE     MIN     MAX     SUBNETS
    master-eu-central-1a    Master  t2.micro        1       1       eu-central-1a
    nodes-eu-central-1a     Node    t2.micro        1       1       eu-central-1a
  12. List the Nodes and Pods to check if all the nodes are ready and running. You can see both master and node are ready status.
    [email protected]:~$ kubectl get nodes
    NAME                                             STATUS   ROLES    AGE     VERSION
    ip-172-20-39-172.eu-central-1.compute.internal   Ready    master   11m     v1.19.7
    ip-172-20-56-248.eu-central-1.compute.internal   Ready    node     6m58s   v1.19.7
  13. You can check all the pods running in the Kubernetes cluster.
    [email protected]:~$ kubectl get pods --all-namespaces
    NAMESPACE     NAME                                                                     READY   STATUS    RESTARTS   AGE
    kube-system   dns-controller-8d8889c4b-xp9dl                                           1/1     Running   0          9m16s
    kube-system   etcd-manager-events-ip-172-20-39-172.eu-central-1.compute.internal       1/1     Running   0          11m
    kube-system   etcd-manager-main-ip-172-20-39-172.eu-central-1.compute.internal         1/1     Running   0          11m
    kube-system   kOps-controller-9skdk                                                    1/1     Running   3          8m51s
    kube-system   kube-apiserver-ip-172-20-39-172.eu-central-1.compute.internal            2/2     Running   0          11m
    kube-system   kube-controller-manager-ip-172-20-39-172.eu-central-1.compute.internal   1/1     Running   6          11m
    kube-system   kube-dns-696cb84c7-g8nhb                                                 3/3     Running   0          5m37s
    kube-system   kube-dns-autoscaler-55f8f75459-zlxbr                                     1/1     Running   0          9m16s
    kube-system   kube-proxy-ip-172-20-39-172.eu-central-1.compute.internal                1/1     Running   0          11m
    kube-system   kube-proxy-ip-172-20-56-248.eu-central-1.compute.internal                1/1     Running   0          8m4s
    kube-system   kube-scheduler-ip-172-20-39-172.eu-central-1.compute.internal            1/1     Running   5          11m

How to Delete a Cluster

Just like creating a Kubernetes cluster, deleting a Kubernetes cluster also using kOps is very simple. This will remove all the cloud resources of the cluster and the cluster registry itself.

[email protected]:~$ kOps delete cluster --name kOpsdemo1.k8s.local --yes
TYPE                    NAME                                                                            ID
autoscaling-config      master-eu-central-1a.masters.kOpsdemo1.k8s.local                                lt-0cc11aec1943204e4
autoscaling-config      nodes-eu-central-1a.kOpsdemo1.k8s.local                                         lt-0da65d2eaf6de9f5c
autoscaling-group       master-eu-central-1a.masters.kOpsdemo1.k8s.local                                master-eu-central-1a.masters.kOpsdemo1.k8s.local
autoscaling-group       nodes-eu-central-1a.kOpsdemo1.k8s.local                                         nodes-eu-central-1a.kOpsdemo1.k8s.local
dhcp-options            kOpsdemo1.k8s.local                                                             dopt-0403a0cbbfbc0c72b
iam-instance-profile    masters.kOpsdemo1.k8s.local                                                     masters.kOpsdemo1.k8s.local
iam-instance-profile    nodes.kOpsdemo1.k8s.local                                                       nodes.kOpsdemo1.k8s.local
iam-role                masters.kOpsdemo1.k8s.local                                                     masters.kOpsdemo1.k8s.local
iam-role                nodes.kOpsdemo1.k8s.local                                                       nodes.kOpsdemo1.k8s.local
instance                master-eu-central-1a.masters.kOpsdemo1.k8s.local                                i-069c73f2c23eb502a
instance                nodes-eu-central-1a.kOpsdemo1.k8s.local                                         i-0401d6b0d4fc11e77
iam-instance-profile:nodes.kOpsdemo1.k8s.local  ok
load-balancer:api-kOpsdemo1-k8s-local-dason2    ok
iam-instance-profile:masters.kOpsdemo1.k8s.local        ok
iam-role:masters.kOpsdemo1.k8s.local    ok
instance:i-069c73f2c23eb502a    ok
autoscaling-group:nodes-eu-central-1a.kOpsdemo1.k8s.local       ok
iam-role:nodes.kOpsdemo1.k8s.local      ok
instance:i-0401d6b0d4fc11e77    ok
autoscaling-config:lt-0cc11aec1943204e4 ok
autoscaling-config:lt-0da65d2eaf6de9f5c ok
autoscaling-group:master-eu-central-1a.masters.kOpsdemo1.k8s.local      ok
keypair:key-0e93f855f382a68fb   ok
Deleted kubectl config for kOpsdemo1.k8s.local
Deleted cluster: "kOpsdemo1.k8s.local"

Conclusion

In this article, you’ve learned that kOps is a great tool to use for managing Kubernetes clusters hosted on various public cloud platforms because of the ways it can reduce the complexity. You’ve also learned the top kOps commands to know when working with Kubernetes, as well as and how to set up kubernetes containers on AWS.

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