Creating Kubernetes Clusters on AWS using KOPS

March 23, 2017 0 45
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Why Kubernetes?

Kubernetes is an open source system for automating deployment, scaling, and management of containerized applications. Kubernetes has emerged as the go-to solution for all your distributed architecture queries. It groups containers that make up an application into logical units for easy management and discovery. But how do you actually provision and deploy a production-ready Kubernetes cluster while ensuring high availability?
The answer is KOPS.

Why KOPS?

KOPS offers a one-stop solution for deploying Kubernetes cluster with Amazon Web Services.It is an open source tool designed to make installation of secure, highly available clusters easy and automatable. In this blog, we will focus on launching cluster in private topology.

Prerequisite

If you don’t have an  AWS account visit https://aws.amazon.com/ to create one.

3.AWS Access key and Secret key of AWS account.

Step 1 | Install KOPS 1.5.1

To spin-up Kubernetes cluster,we need to install the CLI tool kops.

Download KOPS latest release here.

$ wget  https://github.com/kubernetes/kops/releases/download/1.5.1/kops-linux-amd64

To change Permissions, use the following command:

$ chmod a+x kops-linux-amd64

Move KOPS to /usr/local/bin

$ sudo mv kops-linux-amd64 /usr/local/bin/kops

Confirm KOPS installation,

$ kops

Your output is:
kops is kubernetes ops.

It allows you to create, destroy, upgrade and maintain clusters.

Usage:
  kops [command]

Available Commands
completion  Output shell completion code for the given shell (bash)
  create          Create a resource by filename or stdin
  delete          delete clusters
  describe      describe objects


edit               Edit resource
  export          export clusters/kubecfg
  get                list or get objects
  import          import clusters
  replace        Replace a resource by filename or stdin rolling-update rolling update 
                  clusters
  secrets        Manage secrets & keys
  toolbox        Misc infrequently used commands
  update         update clusters
  upgrade       upgrade clusters
  validate       Validate Cluster
  version        Print the client 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 (default2)
      -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.

Step 2 | Install Kubectl

To download Kubectl,

$ wget https://storage.googleapis.com/kubernetes-release/release/v1.5.2/bin/linux/amd64/
kubectl

Change Permissions,

$ chmod a+x kubectl

Move kubectl to /usr/local/bin,

$ sudo mv kubectl /usr/local/bin/kubectl

Confirm Kubectl installation,

$ kubectl  

kubectl controls the Kubernetes cluster manager. 

Find more information at 

Basic Commands (Beginner):
create         Create a resource by filename or stdin
expose         Take a replication controller, service, deployment or pod and expose it as a 
               new Kubernetes Service
run            Run a particular image on the cluster
set            Set specific features on objects

For Intermediate:
get            Display one or many resources
explain        Documentation of resources
edit           Edit a resource on the server
delete         Delete resources by filenames, stdin, resources and names, or by resources 
               and label selector

Deploy Commands:

rollout        Manage a deployment rollout
rolling-update Perform a rolling update of the given ReplicationController
scale          Set a new size for a Deployment, ReplicaSet, Replication

Controller, or Job
autoscale      Auto-scale a Deployment, ReplicaSet, or ReplicationController

Cluster Management Commands:

certificate    Modify certificate resources.
cluster-info   Display cluster info
top            Display Resource (CPU/Memory/Storage) usage
cordon         Mark node as unschedulable
uncordon       Mark node as schedulable
drain          Drain node in preparation for maintenance
taint          Update the taints on one or more nodes

Troubleshooting and Debugging Commands:

describe       Show details of a specific resource or group of resources
logs           Print the logs for a container in a pod
attach         Attach to a running container
exec           Execute a command in a container
port-forward   Forward one or more local ports to a pod
proxy          Run a proxy to the Kubernetes API server
cp             Copy files and directories to and from containers.

Advanced Commands:

apply          Apply a configuration to a resource by filename or stdin
patch          Update field(s) of a resource using strategic merge patch
replace        Replace a resource by filename or stdin
convert        Convert config files between different API versions

Settings Commands:

label          Update the labels on a resource
annotate       Update the annotations on a resource
completion     Output shell completion code for the given shell (bash or zsh)


Other Commands:

api-versions   Print the supported API versions on the server, in the form of
"group/version"

config         Modify kubeconfig files
help           Help about any command
version        Print the client and server version information


Use "kubectl <command> --help" for more information about a given command.

Use "kubectl options" for a list of global command-line options (applies to all commands).

Step 3 | Setting up AWS environment

In order to do this we need to first configure AWS with Secret Key and Access Key.The Secret Key and Access Key have all necessary permissions you need to as mentioned in `prerequisite’.   You can also create a separate user for KOPS with this script.

Configure AWS,

$ aws configure

Provide right Secret Key , Access Key and Region.

If you are using script [Which is more recommended],

$ curl -O https://raw.githubusercontent.com/kubernetes/kops/master/hack/new-iam-user.sh

$ sh new-iam-user.sh <group> <user>

$ aws iam list-users

In response you’ll get secret key and access-key for the use. Note down secret key and access-key for this user.

Step 4 | Create Hosted Zone for Cluster

For this we require a  hosted zone associated with Route 53 which must be publicly resolvable. (However KOPS also allows to use private DNS which is more tricky.)

We are creating  Hosted Zone  using testikod.in,

$ aws route53 create-hosted-zone --name testikod.in --caller-reference 2017-02-24-11:12 
--hosted-zone-config Comment="Hosted Zone for KOPS"

Step 5 | Create State Store

KOPS internally uses Terraform . So we required external state store for storing states of a cluster. We are using Amazon S3 for storing state.

$ aws s3api create-bucket --bucket testikod-in-state-store --region us-west-2

Step 6 | Creating Cluster

Setup environment variable for STATE STORE and cluster name NAME:

$ export NAME=cluster.testikod.in

$ export KOPS_STATE_STORE="s3://testikod-in-state-store"

Forming custom KOPS command to use private topology,

Parameters :

--cloud aws : We are launching cluster in AWS.

--zones us-west-2a,us-west-2b,us-west-2c : This describes availability zones for nodes. 
[Note that this availability zones should be available for AWS account. You can check it
 through, aws ec2 describe-availability-zones --region us-west-1 ]

--node-count 5 : The number kubernetes nodes.

--node-size t2.medium : Size of kubernetes nodes.

--dns-zone testikod.in : Hosted zone which we created earlier.

--master-size m3.medium : Size of a Kubernetes master node.

--master-zones us-west-2a,us-west-2b,us-west-2c : This will tell kops to spread masters 
across those availability zones. Which will give High Availability to KOPS cluster.

--topology private : We define that we want to use a private network topology with kops.

--networking calico : We tell kops to use Calico for our overlay network.Overlay networks 
are required for this configuration.

-- bastion : Add this flag to tell kops to create a bastion server so you can SSH into the 
cluster.

KOPS Command,

kops create cluster \
    --cloud aws \
    --node-count 5 \
    --node-size t2.medium \
    --master-size m3.medium \
    --zones us-west-2a,us-west-2b,us-west-2c \
    --master-zones us-west-2a,us-west-2b,us-west-2c \
    --dns-zone testikod.in \
    --topology private \
    --networking calico \
    --bastion \
    ${NAME}

Kops will set default to ~/.ssh/id_rsa.pub for backend access. You can override this with –ssh-public-key /path/to/key.pub

Cluster configuration

Above command will create a blueprint for the cluster. To edit configurations,

$ kops edit cluster ${NAME}

Apply the changes,

$ kops update cluster ${NAME} --yes

Cluster creation will take up to 10 minutes.

Step 7 | Verify cluster and Start using Cluster

Check your API’s are working with kubectl,

$ kubectl get nodes

It should provide you the number of nodes in response.

To access admin via bastion host,

$ exec ssh-agent bash
$ ssh-add ~/.ssh/id_rsa
$ ssh -A admin@bastion.cluster.testikod.in
$ ssh admin@<master_private_ip>

Conclusion:

All things considered, K8S is among the best available container orchestration tools today. It provides a solid platform to provision and deploy clusters. It offers many exciting features and also allows a wide range of customizations.

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