Kubernetes: The components

In previous articles we have seen some details of how the Kubernetes architecture is built.

Today the working mechanisms of the Kubernetes engine will be described indicating the name of each component; to remain faithful to the comparison of the car engine, we will speak of the camshafts, valves, bearings, … that belong to the Cloud Native

Note 1: The installation of k8s in Datacenter, Cloud, and Laboratory will not be discussed, the network has already made comprehensive tutorials available.

To familiarize yourself with k8s I recommend using Minikube (Linux platform) Docker Desktop (Windows & Mac platform).

Let’s begin!

Kubernetes Master:It is the main node of the cluster on which three processes that are vital for the existence of the cluster run.

  • kube-apiserver
  • kube-controller-manager
  • Kube-scheduler

In the master node, there is also the DataBase etcd, which stores all configurations created in the cluster.

The nodes that take care of running the applications and therefore the services are said worker node. The processes present on the worker node I’m:

  • Kubelet
  • kube-proxy

kubectl : AND’ The official Kubernetes client ( CLI ) through which you can manage the cluster ( Kube-apiserver ) using the API.

Some simple examples of kubectl commands are:

  • kubectl version (indicates the version of k8s installed)
  • kubectl get nodes (find out the number of nodes in the cluster)
  • kubectl describe nodes nodes-1 (shows the health status of the node, the platform on which k8s is running (Google, AWS, ….) and the allocated resources (CPU, RAM)).

Kube-Proxy : He is responsible for managing networking, from Routing to Load Balancing rules.

Note 2 : K8s will try to use them all libraries available at the level of operating system .

Container Runtime : It is the foundation on which the k8s technology rests.

kubernetes supports several runtimes among which we remember, container-d , cri-o , rktlet .

Note 3 : The runtime Docker it has been deprecated in favor of those that use interfaces CRI ; Docker images will still continue to work in the cluster.

The objects Kubernetes base are:

  • Pod
  • Services
  • Volumes
  • Namespace

THE controller provide additional functionality and are:

  • ReplicaSet
  • Deployment
  • StatefulSet
  • DaemonSet
  • Job

Between Deployment it is imperative to mention Kube-DNS which provides name resolution services. Since kubernetes version 1.2 the name has changed to Core-dns.

Add-On : they are used to configure further cluster functions and are placed inside the name space kube-system (such as Kube-Proxy, Kube-DNS, kube-Dashboard)

Add-ons are categorized according to their use:

  • Add-on of Netwok policy . (For example the NSX-T add-on takes care of the communication between the K8s environment and VMware)
  • Add-on Infrastructural (For example KubeVirt which allows connection with virtual architectures)
  • Add-on of Visualization and Control (For example Dashboard a web interface for K8s).

For commissioning, Add-ons use controllers DaemonSet And Deployment .

The image in figure 1 summarizes what has just been explained.

Figure 1

Take care and see you soon.

VDrO-Baseline 1

August’s 2022 topic is VDrO (former VAO)

This topic needs an awfully long time to be rightly covered. For this reason, I wrote 5 articles.

The first two will explain the base concepts in front of technology. The others will cover how to set up VDrO for managing the Veeam Replica job, the Veeam Backup job, and the Netapp Storage Replica.

Here below all the direct links to the topic:

Baseline-2VBR-ReplicasVeeam BackupNetapp integration

In these articles, I will not manage how to install VDO software; please refer to the deployment guide (VDrO Guides).

  1. VDrO – Baseline-1:

One of the common requirements of big companies is to automatically manage Disaster Recovery.

Let’s see the decisional process of the IT Manager

These are the VDrO answers.

Let’s move to the VDrO console:

The first steps after logging in (picture 1) is to click on the administrator tab (Yellow on picture 2) and check the license file installed (picture  3)

Picture 1

Picture 2

https://lnx.gable.it/wp-content/uploads/2020/07/VAO-login.jpgPicture 3

Now I’m going to describe the structure of the software components.

VDrO Server:  it shows where the VDrO Server has been installed (Picture 4)

Picture 4

The VDrO architecture is well-represented in picture 5 where three production sites replicate their data to a DR site.

Picture 5

Is it important to fill up the VDrO Server form? Yes, because VDrO creates automatically the DR- Plan documentation.

In my lab, I have just a production site and a  DR site.

VDrO AGENTS: to control the activities of the Backup Server located in production sites, VDrO installs his own agent. The installation task is performed directly from the VDrO console (Picture 6).

Picture 6

vCENTER SERVERS: in my scenario, there are two vCenters; the first one in production and the second in DR site (Picture 7).

(Picture 7)

STORAGE SYSTEM: the most important VDrO news is the integration with storage replication technology. This version supports just Netapp. Picture 8 shows how to add the Storages to VDrO.

Picture 8

The last VDrO article will deal with how to set up and use this great technology.

RECOVERY LOCATION: it’s the place where the DR will be performed (Picture 9). It can be different locations in respect to where VDrO is installed.

Picture 9

In the next rows and pictures, I’ll show which info VDrO needs to work at its best.

In particular, I’m talking about the resources present in the recovery location. In this example the computer resources (Picture 10) and storage resources (picture 11).

Picture 10

Picture 11

The next 10 rows are very important to fix in mind.

How the VDrO can understand which resources are available? In other words, how can I assign resources to my Failover Plan?

The answer is VDrO uses massively tagging to all resources present at the VMware level.

Tagging means that resources can be added to VDRO

But …. is it possible to tag the resources?

Yes, It’s possible because inside VDrO there is the Veeam ONE Business-View component that can be freely used to tag resources.

To have more details about tagging please refer to the VDrO-guide.

One of the most common requests from the customers is to create automatic documentation about failover for both testing and procedures.

VDrO has already templates (in different languages that you can personalize at will) that are automatically filled up from software when you test or perform the Disaster Recovery.

In the next two pictures, it is shown how to set up an e-mail subscription (Picture 12) and configure the report Detail level (Picture 13).

Just remember to subscribe to the report to the right scope.

(Picture 12)

(Picture 13)

The next option is the reason why I fell in love with VDrO (Picture 14).

(Picture 14)

As you can see there is a big choice with DR plan steps. What does it mean?

Let’s see it with an easy example:

My DR plan requires switching on the Domain Controller (VM1) and afterward the SQL Application (VM2).

I want also to be sure that

a. the original VMs are switched off before starting the DR plan

b.  when DR-plan is up and running, the SQL application has to answer port 1433.

What the VDrO can do for you?

With the pre-plan step, you can check the original VMs are switched off.

With a post-plan, you can check that the application answers correctly.

Another great point about plan steps is that you can choose if the actions have to be executed or skipped. In this way, it adds more flexibility to the solution.

(Picture 15)

Picture 16

It’s time to have a break. My next Article (VDrO – Baseline 2) will show scopes and plan components.