The document discusses setting up a highly available (HA) Kubernetes cluster. It describes the master-worker architecture of Kubernetes and explains that to achieve high availability, both the control plane (master components) and node plane need replication. It provides details on replicating the etcd database, API server, and controller/scheduler components across multiple machines. It also discusses considerations for load balancing the API server and placing components across availability zones. While a HA cluster improves fault tolerance, it involves more complexity, so the document discusses when a single master may suffice and factors to consider in that decision.
A Comprehensive Introduction to Kubernetes. This slide deck serves as the lecture portion of a full-day Workshop covering the architecture, concepts and components of Kubernetes. For the interactive portion, please see the tutorials here:
https://github.com/mrbobbytables/k8s-intro-tutorials
In this session, we will discuss the architecture of a Kubernetes cluster. we will go through all the master and worker components of a kubernetes cluster. We will also discuss the basic terminology of Kubernetes cluster such as Pods, Deployments, Service etc. We will also cover networking inside Kuberneets. In the end, we will discuss options available for the setup of a Kubernetes cluster.
A Comprehensive Introduction to Kubernetes. This slide deck serves as the lecture portion of a full-day Workshop covering the architecture, concepts and components of Kubernetes. For the interactive portion, please see the tutorials here:
https://github.com/mrbobbytables/k8s-intro-tutorials
In this session, we will discuss the architecture of a Kubernetes cluster. we will go through all the master and worker components of a kubernetes cluster. We will also discuss the basic terminology of Kubernetes cluster such as Pods, Deployments, Service etc. We will also cover networking inside Kuberneets. In the end, we will discuss options available for the setup of a Kubernetes cluster.
Kubernetes Concepts And Architecture Powerpoint Presentation SlidesSlideTeam
Get these visually appealing Kubernetes Concepts And Architecture PowerPoint Presentation Slides to discuss the process of operating containerized applications. You can display the need for containers by the company with the help of an open-source architecture PPT slideshow. The architecture of containers can be demonstrated with the help of a visually appealing PPT slideshow. The reasons for opting for Kubernetes by an organization can be explained to your teammates with the help of containers PowerPoint infographics. Highlight the roadmap for installing Kubernetes in the organization by using content-ready PPT slides. Take the assistance of visually appealing PPT templates to depict the major advantages of Kubernetes such as improving productivity, the stability of application run, and many more. After that, display 30 60 90 days plan to implement Kubernetes in the organization. Display the key components of Kubernetes with the help of a diagram using this professionally designed cluster architecture PPT layouts. Describe the functionality of each components of Kubernetes. Hence, download Kubernetes architecture PPT slides to easily and efficiently manage the clusters. https://bit.ly/34DWa7x
Kubernetes for Beginners: An Introductory GuideBytemark
An introduction to Kubernetes for beginners. Includes the definition, architecture, benefits and misconceptions of Kubernetes. Written in plain English, ideal for both developers and non-developers who are new to Kubernetes.
Find out more about Kubernetes at Bytemark here: https://www.bytemark.co.uk/managed-kubernetes/
K8s in 3h - Kubernetes Fundamentals TrainingPiotr Perzyna
Kubernetes (K8s) is an open-source system for automating deployment, scaling, and management of containerized applications. This training helps you understand key concepts within 3 hours.
A basic introductory slide set on Kubernetes: What does Kubernetes do, what does Kubernetes not do, which terms are used (Containers, Pods, Services, Replica Sets, Deployments, etc...) and how basic interaction with a Kubernetes cluster is done.
Traditional virtualization technologies have been used by cloud infrastructure providers for many years in providing isolated environments for hosting applications. These technologies make use of full-blown operating system images for creating virtual machines (VMs). According to this architecture, each VM needs its own guest operating system to run application processes. More recently, with the introduction of the Docker project, the Linux Container (LXC) virtualization technology became popular and attracted the attention. Unlike VMs, containers do not need a dedicated guest operating system for providing OS-level isolation, rather they can provide the same level of isolation on top of a single operating system instance.
An enterprise application may need to run a server cluster to handle high request volumes. Running an entire server cluster on Docker containers, on a single Docker host could introduce the risk of single point of failure. Google started a project called Kubernetes to solve this problem. Kubernetes provides a cluster of Docker hosts for managing Docker containers in a clustered environment. It provides an API on top of Docker API for managing docker containers on multiple Docker hosts with many more features.
** Kubernetes Certification Training: https://www.edureka.co/kubernetes-certification **
This Edureka tutorial on "Kubernetes Architecture" will give you an introduction to popular DevOps tool - Kubernetes, and will deep dive into Kubernetes Architecture and its working. The following topics are covered in this training session:
1. What is Kubernetes
2. Features of Kubernetes
3. Kubernetes Architecture and Its Components
4. Components of Master Node and Worker Node
5. ETCD
6. Network Setup Requirements
DevOps Tutorial Blog Series: https://goo.gl/P0zAfF
A basic introduction to Kubernetes. Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications.
This presentation covers how app deployment model evolved from bare metal servers to Kubernetes World.
In addition to theoretical information, you will find free KATACODA workshops url to perform practices to understand the details of the each topics.
- Archeology: before and without Kubernetes
- Deployment: kube-up, DCOS, GKE
- Core Architecture: the apiserver, the kubelet and the scheduler
- Compute Model: the pod, the service and the controller
Dockerized containers are the current wave that promising to revolutionize IT. Everybody is talking about containers, but a lot of people remain confused on how they work and why they are different or better than virtual machines. In this session, Black Duck container and virtualization expert Tim Mackey will demystify containers, explain their core concepts, and compare and contrast them with the virtual machine architectures that have been the staple of IT for the last decade.
Tell the history of Container/Docker/Kubernetes, and show the key elements of them.
After view this document, you could know the main feature of Container Docker and Kubernetes.
Very basic infomation about how these technique work together.
Author: Oleg Chunikhin, www.eastbanctech.com
Kubernetes is a portable open source system for managing and orchestrating containerized cluster applications. Kubernetes solves a number of DevOps related problems out of the box in a simple and unified way – rolling updates and update rollback, canary deployment and other complicated deployment scenarios, scaling, load balancing, service discovery, logging, monitoring, persistent storage management, and much more. You will learn how in less than 30 minutes a reliable self-healing production-ready Kubernetes cluster may be deployed on AWS and used to host and operate multiple environments and applications.
If you’re working with just a few containers, managing them isn't too complicated. But what if you have hundreds or thousands? Think about having to handle multiple upgrades for each container, keeping track of container and node state, available resources, and more. That’s where Kubernetes comes in. Kubernetes is an open source container management platform that helps you run containers at scale. This talk will cover Kubernetes components and show how to run applications on it.
Kubernetes Concepts And Architecture Powerpoint Presentation SlidesSlideTeam
Get these visually appealing Kubernetes Concepts And Architecture PowerPoint Presentation Slides to discuss the process of operating containerized applications. You can display the need for containers by the company with the help of an open-source architecture PPT slideshow. The architecture of containers can be demonstrated with the help of a visually appealing PPT slideshow. The reasons for opting for Kubernetes by an organization can be explained to your teammates with the help of containers PowerPoint infographics. Highlight the roadmap for installing Kubernetes in the organization by using content-ready PPT slides. Take the assistance of visually appealing PPT templates to depict the major advantages of Kubernetes such as improving productivity, the stability of application run, and many more. After that, display 30 60 90 days plan to implement Kubernetes in the organization. Display the key components of Kubernetes with the help of a diagram using this professionally designed cluster architecture PPT layouts. Describe the functionality of each components of Kubernetes. Hence, download Kubernetes architecture PPT slides to easily and efficiently manage the clusters. https://bit.ly/34DWa7x
Kubernetes for Beginners: An Introductory GuideBytemark
An introduction to Kubernetes for beginners. Includes the definition, architecture, benefits and misconceptions of Kubernetes. Written in plain English, ideal for both developers and non-developers who are new to Kubernetes.
Find out more about Kubernetes at Bytemark here: https://www.bytemark.co.uk/managed-kubernetes/
K8s in 3h - Kubernetes Fundamentals TrainingPiotr Perzyna
Kubernetes (K8s) is an open-source system for automating deployment, scaling, and management of containerized applications. This training helps you understand key concepts within 3 hours.
A basic introductory slide set on Kubernetes: What does Kubernetes do, what does Kubernetes not do, which terms are used (Containers, Pods, Services, Replica Sets, Deployments, etc...) and how basic interaction with a Kubernetes cluster is done.
Traditional virtualization technologies have been used by cloud infrastructure providers for many years in providing isolated environments for hosting applications. These technologies make use of full-blown operating system images for creating virtual machines (VMs). According to this architecture, each VM needs its own guest operating system to run application processes. More recently, with the introduction of the Docker project, the Linux Container (LXC) virtualization technology became popular and attracted the attention. Unlike VMs, containers do not need a dedicated guest operating system for providing OS-level isolation, rather they can provide the same level of isolation on top of a single operating system instance.
An enterprise application may need to run a server cluster to handle high request volumes. Running an entire server cluster on Docker containers, on a single Docker host could introduce the risk of single point of failure. Google started a project called Kubernetes to solve this problem. Kubernetes provides a cluster of Docker hosts for managing Docker containers in a clustered environment. It provides an API on top of Docker API for managing docker containers on multiple Docker hosts with many more features.
** Kubernetes Certification Training: https://www.edureka.co/kubernetes-certification **
This Edureka tutorial on "Kubernetes Architecture" will give you an introduction to popular DevOps tool - Kubernetes, and will deep dive into Kubernetes Architecture and its working. The following topics are covered in this training session:
1. What is Kubernetes
2. Features of Kubernetes
3. Kubernetes Architecture and Its Components
4. Components of Master Node and Worker Node
5. ETCD
6. Network Setup Requirements
DevOps Tutorial Blog Series: https://goo.gl/P0zAfF
A basic introduction to Kubernetes. Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications.
This presentation covers how app deployment model evolved from bare metal servers to Kubernetes World.
In addition to theoretical information, you will find free KATACODA workshops url to perform practices to understand the details of the each topics.
- Archeology: before and without Kubernetes
- Deployment: kube-up, DCOS, GKE
- Core Architecture: the apiserver, the kubelet and the scheduler
- Compute Model: the pod, the service and the controller
Dockerized containers are the current wave that promising to revolutionize IT. Everybody is talking about containers, but a lot of people remain confused on how they work and why they are different or better than virtual machines. In this session, Black Duck container and virtualization expert Tim Mackey will demystify containers, explain their core concepts, and compare and contrast them with the virtual machine architectures that have been the staple of IT for the last decade.
Tell the history of Container/Docker/Kubernetes, and show the key elements of them.
After view this document, you could know the main feature of Container Docker and Kubernetes.
Very basic infomation about how these technique work together.
Author: Oleg Chunikhin, www.eastbanctech.com
Kubernetes is a portable open source system for managing and orchestrating containerized cluster applications. Kubernetes solves a number of DevOps related problems out of the box in a simple and unified way – rolling updates and update rollback, canary deployment and other complicated deployment scenarios, scaling, load balancing, service discovery, logging, monitoring, persistent storage management, and much more. You will learn how in less than 30 minutes a reliable self-healing production-ready Kubernetes cluster may be deployed on AWS and used to host and operate multiple environments and applications.
If you’re working with just a few containers, managing them isn't too complicated. But what if you have hundreds or thousands? Think about having to handle multiple upgrades for each container, keeping track of container and node state, available resources, and more. That’s where Kubernetes comes in. Kubernetes is an open source container management platform that helps you run containers at scale. This talk will cover Kubernetes components and show how to run applications on it.
An in depth overview of Kubernetes and it's various components.
NOTE: This is a fixed version of a previous presentation (a draft was uploaded with some errors)
Container Orchestration with Docker Swarm and KubernetesWill Hall
This presentation covers the basics of what container orchestration is providing pros and cons of Docker Swarm, Kubernetes and Amazon ECS and outlining the terms and tools you will need to successfully use them.
This presentation is about the AKS components as listed below.
- Control plane
- Different types of control planes & OS types
- Node pools
- Node
- Pod
- Resource reservation
- Node selectors
- Namespaces
- StatefulSets and DaemonSets
- Terraform deployment and Azure Portal demonstration
Youtube video for this slide: https://youtu.be/yOsrai6id9I
GitHub repo for these slides: https://github.com/ParisaMousavi/enterprise-aks
WordPress post: https://multi-cloud-solutions.com/2022/11/30/azure-kubernetes-service-aks-with-terraform-deployment/
Recent momentum around the evolution of Containers are gradually increase in last two years.Containers virtualize an OS and applications running in each container believe that they have full access to their very own copy of that OS. This is analogous to what VMs do when they virtualize at a lower level, the hardware. In the case of containers, it’s the OS that does the virtualization and maintains the illusion.
Recent past many software companies have quickly adopted container technologies, including Docker Containers, aware of the threat and advantage of the approach. For example, Linux companies have also jumped into the ground, seeing as this as an opportunity to grow the Linux market. Also Microsoft is going to add features to support containers and VMware have made efforts in integrating support for Docker into virtual machine technology.
Recent momentum around the evolution of Containers are gradually increase in last two years.Containers virtualize an OS and applications running in each container believe that they have full access to their very own copy of that OS. This is analogous to what VMs do when they virtualize at a lower level, the hardware. In the case of containers, it’s the OS that does the virtualization and maintains the illusion.
Recent past many software companies have quickly adopted container technologies, including Docker Containers, aware of the threat and advantage of the approach. For example, Linux companies have also jumped into the ground, seeing as this as an opportunity to grow the Linux market. Also Microsoft is going to add features to support containers and VMware have made efforts in integrating support for Docker into virtual machine technology.
ARCHITECTING TENANT BASED QOS IN MULTI-TENANT CLOUD PLATFORMSArun prasath
Achieving QOS in a multi-tenant cloud platforms is still a difficult task and many companies follow different approaches to solve this problem. Here in this document I tried architecting a simple solution for achieving different QOS for different tenants in a Multi-tenant cloud environment based on my experiments with containers , docker and cgroup on Openstack.
This is the most basic presentation introducing to the concepts of kubernetes this presentation only solves the mundane purpose as a visual aid to the session
First Steps with Globus Compute Multi-User EndpointsGlobus
In this presentation we will share our experiences around getting started with the Globus Compute multi-user endpoint. Working with the Pharmacology group at the University of Auckland, we have previously written an application using Globus Compute that can offload computationally expensive steps in the researcher's workflows, which they wish to manage from their familiar Windows environments, onto the NeSI (New Zealand eScience Infrastructure) cluster. Some of the challenges we have encountered were that each researcher had to set up and manage their own single-user globus compute endpoint and that the workloads had varying resource requirements (CPUs, memory and wall time) between different runs. We hope that the multi-user endpoint will help to address these challenges and share an update on our progress here.
A Comprehensive Look at Generative AI in Retail App Testing.pdfkalichargn70th171
Traditional software testing methods are being challenged in retail, where customer expectations and technological advancements continually shape the landscape. Enter generative AI—a transformative subset of artificial intelligence technologies poised to revolutionize software testing.
Quarkus Hidden and Forbidden ExtensionsMax Andersen
Quarkus has a vast extension ecosystem and is known for its subsonic and subatomic feature set. Some of these features are not as well known, and some extensions are less talked about, but that does not make them less interesting - quite the opposite.
Come join this talk to see some tips and tricks for using Quarkus and some of the lesser known features, extensions and development techniques.
We describe the deployment and use of Globus Compute for remote computation. This content is aimed at researchers who wish to compute on remote resources using a unified programming interface, as well as system administrators who will deploy and operate Globus Compute services on their research computing infrastructure.
Experience our free, in-depth three-part Tendenci Platform Corporate Membership Management workshop series! In Session 1 on May 14th, 2024, we began with an Introduction and Setup, mastering the configuration of your Corporate Membership Module settings to establish membership types, applications, and more. Then, on May 16th, 2024, in Session 2, we focused on binding individual members to a Corporate Membership and Corporate Reps, teaching you how to add individual members and assign Corporate Representatives to manage dues, renewals, and associated members. Finally, on May 28th, 2024, in Session 3, we covered questions and concerns, addressing any queries or issues you may have.
For more Tendenci AMS events, check out www.tendenci.com/events
Check out the webinar slides to learn more about how XfilesPro transforms Salesforce document management by leveraging its world-class applications. For more details, please connect with sales@xfilespro.com
If you want to watch the on-demand webinar, please click here: https://www.xfilespro.com/webinars/salesforce-document-management-2-0-smarter-faster-better/
OpenFOAM solver for Helmholtz equation, helmholtzFoam / helmholtzBubbleFoamtakuyayamamoto1800
In this slide, we show the simulation example and the way to compile this solver.
In this solver, the Helmholtz equation can be solved by helmholtzFoam. Also, the Helmholtz equation with uniformly dispersed bubbles can be simulated by helmholtzBubbleFoam.
Custom Healthcare Software for Managing Chronic Conditions and Remote Patient...Mind IT Systems
Healthcare providers often struggle with the complexities of chronic conditions and remote patient monitoring, as each patient requires personalized care and ongoing monitoring. Off-the-shelf solutions may not meet these diverse needs, leading to inefficiencies and gaps in care. It’s here, custom healthcare software offers a tailored solution, ensuring improved care and effectiveness.
AI Pilot Review: The World’s First Virtual Assistant Marketing SuiteGoogle
AI Pilot Review: The World’s First Virtual Assistant Marketing Suite
👉👉 Click Here To Get More Info 👇👇
https://sumonreview.com/ai-pilot-review/
AI Pilot Review: Key Features
✅Deploy AI expert bots in Any Niche With Just A Click
✅With one keyword, generate complete funnels, websites, landing pages, and more.
✅More than 85 AI features are included in the AI pilot.
✅No setup or configuration; use your voice (like Siri) to do whatever you want.
✅You Can Use AI Pilot To Create your version of AI Pilot And Charge People For It…
✅ZERO Manual Work With AI Pilot. Never write, Design, Or Code Again.
✅ZERO Limits On Features Or Usages
✅Use Our AI-powered Traffic To Get Hundreds Of Customers
✅No Complicated Setup: Get Up And Running In 2 Minutes
✅99.99% Up-Time Guaranteed
✅30 Days Money-Back Guarantee
✅ZERO Upfront Cost
See My Other Reviews Article:
(1) TubeTrivia AI Review: https://sumonreview.com/tubetrivia-ai-review
(2) SocioWave Review: https://sumonreview.com/sociowave-review
(3) AI Partner & Profit Review: https://sumonreview.com/ai-partner-profit-review
(4) AI Ebook Suite Review: https://sumonreview.com/ai-ebook-suite-review
TROUBLESHOOTING 9 TYPES OF OUTOFMEMORYERRORTier1 app
Even though at surface level ‘java.lang.OutOfMemoryError’ appears as one single error; underlyingly there are 9 types of OutOfMemoryError. Each type of OutOfMemoryError has different causes, diagnosis approaches and solutions. This session equips you with the knowledge, tools, and techniques needed to troubleshoot and conquer OutOfMemoryError in all its forms, ensuring smoother, more efficient Java applications.
Accelerate Enterprise Software Engineering with PlatformlessWSO2
Key takeaways:
Challenges of building platforms and the benefits of platformless.
Key principles of platformless, including API-first, cloud-native middleware, platform engineering, and developer experience.
How Choreo enables the platformless experience.
How key concepts like application architecture, domain-driven design, zero trust, and cell-based architecture are inherently a part of Choreo.
Demo of an end-to-end app built and deployed on Choreo.
Software Engineering, Software Consulting, Tech Lead.
Spring Boot, Spring Cloud, Spring Core, Spring JDBC, Spring Security,
Spring Transaction, Spring MVC,
Log4j, REST/SOAP WEB-SERVICES.
Unleash Unlimited Potential with One-Time Purchase
BoxLang is more than just a language; it's a community. By choosing a Visionary License, you're not just investing in your success, you're actively contributing to the ongoing development and support of BoxLang.
Code reviews are vital for ensuring good code quality. They serve as one of our last lines of defense against bugs and subpar code reaching production.
Yet, they often turn into annoying tasks riddled with frustration, hostility, unclear feedback and lack of standards. How can we improve this crucial process?
In this session we will cover:
- The Art of Effective Code Reviews
- Streamlining the Review Process
- Elevating Reviews with Automated Tools
By the end of this presentation, you'll have the knowledge on how to organize and improve your code review proces
Innovating Inference - Remote Triggering of Large Language Models on HPC Clus...Globus
Large Language Models (LLMs) are currently the center of attention in the tech world, particularly for their potential to advance research. In this presentation, we'll explore a straightforward and effective method for quickly initiating inference runs on supercomputers using the vLLM tool with Globus Compute, specifically on the Polaris system at ALCF. We'll begin by briefly discussing the popularity and applications of LLMs in various fields. Following this, we will introduce the vLLM tool, and explain how it integrates with Globus Compute to efficiently manage LLM operations on Polaris. Attendees will learn the practical aspects of setting up and remotely triggering LLMs from local machines, focusing on ease of use and efficiency. This talk is ideal for researchers and practitioners looking to leverage the power of LLMs in their work, offering a clear guide to harnessing supercomputing resources for quick and effective LLM inference.
Prosigns: Transforming Business with Tailored Technology SolutionsProsigns
Unlocking Business Potential: Tailored Technology Solutions by Prosigns
Discover how Prosigns, a leading technology solutions provider, partners with businesses to drive innovation and success. Our presentation showcases our comprehensive range of services, including custom software development, web and mobile app development, AI & ML solutions, blockchain integration, DevOps services, and Microsoft Dynamics 365 support.
Custom Software Development: Prosigns specializes in creating bespoke software solutions that cater to your unique business needs. Our team of experts works closely with you to understand your requirements and deliver tailor-made software that enhances efficiency and drives growth.
Web and Mobile App Development: From responsive websites to intuitive mobile applications, Prosigns develops cutting-edge solutions that engage users and deliver seamless experiences across devices.
AI & ML Solutions: Harnessing the power of Artificial Intelligence and Machine Learning, Prosigns provides smart solutions that automate processes, provide valuable insights, and drive informed decision-making.
Blockchain Integration: Prosigns offers comprehensive blockchain solutions, including development, integration, and consulting services, enabling businesses to leverage blockchain technology for enhanced security, transparency, and efficiency.
DevOps Services: Prosigns' DevOps services streamline development and operations processes, ensuring faster and more reliable software delivery through automation and continuous integration.
Microsoft Dynamics 365 Support: Prosigns provides comprehensive support and maintenance services for Microsoft Dynamics 365, ensuring your system is always up-to-date, secure, and running smoothly.
Learn how our collaborative approach and dedication to excellence help businesses achieve their goals and stay ahead in today's digital landscape. From concept to deployment, Prosigns is your trusted partner for transforming ideas into reality and unlocking the full potential of your business.
Join us on a journey of innovation and growth. Let's partner for success with Prosigns.
SOCRadar Research Team: Latest Activities of IntelBrokerSOCRadar
The European Union Agency for Law Enforcement Cooperation (Europol) has suffered an alleged data breach after a notorious threat actor claimed to have exfiltrated data from its systems. Infamous data leaker IntelBroker posted on the even more infamous BreachForums hacking forum, saying that Europol suffered a data breach this month.
The alleged breach affected Europol agencies CCSE, EC3, Europol Platform for Experts, Law Enforcement Forum, and SIRIUS. Infiltration of these entities can disrupt ongoing investigations and compromise sensitive intelligence shared among international law enforcement agencies.
However, this is neither the first nor the last activity of IntekBroker. We have compiled for you what happened in the last few days. To track such hacker activities on dark web sources like hacker forums, private Telegram channels, and other hidden platforms where cyber threats often originate, you can check SOCRadar’s Dark Web News.
Stay Informed on Threat Actors’ Activity on the Dark Web with SOCRadar!
Globus Connect Server Deep Dive - GlobusWorld 2024Globus
We explore the Globus Connect Server (GCS) architecture and experiment with advanced configuration options and use cases. This content is targeted at system administrators who are familiar with GCS and currently operate—or are planning to operate—broader deployments at their institution.
Globus Connect Server Deep Dive - GlobusWorld 2024
Highly available (ha) kubernetes
1. Highly Available (HA) Kubernetes
Kubernetes — master and worker (node) components
Kubernetes is a master-slave type of architecture with certain components (master
components) calling the shots in the cluster, and other components (node
components) executing application workloads (containers) as decided by the
master components.
Kubernetes — master and worker (node) components The node components run on every cluster node.
The master components manage the state of the cluster. This includes accepting
client requests (describing the desired state), scheduling containers and running
control loops to drive the actual cluster state towards the desired state.
These components are:
apiserver: a REST API supporting basic CRUD operations on API objects (such as
pods, deployments, and services).
This is the endpoint that a cluster administrator communicates with, for example,
using kubectl.
The apiserver, in itself, is stateless. Instead it uses a distributed key-value storage
system (etcd) as its backend for storing all cluster state.
Controller managers: runs the control/reconciliation loops that watch the desired
state in the apiserver and attempt to move the actual state towards the desired
state. Internally it consists of many different controllers, of which the replication
controller is a prominent one ensuring that the right numbers of replica pods are
running for each deployment.
scheduler: takes care of pod placement across the set of available nodes, striving
to balance resource consumption
to not place excessive load on any cluster node. It also takes user scheduling
restrictions into account, such as (anti-)affinity rules.
These components are:
Container runtime: such as Docker, to execute containers on the node.
kubelet: executes containers (pods) on the node as dictated by the control plane’s
scheduling, and ensures the health of those pods (for example, by restarting failed
pods).
kube-proxy: a network proxy/LoadBalancer that implements the Service
abstraction. It programs the iptables rules on the node to redirect service IP
requests to one of its registered backend pods.
There is no formal requirement for master components to run on any particular
host in the cluster, however, typically these control-plane components are grouped
together to run one or more master nodes. With the exception of etcd,
which may be set up to run on its own machine(s), these master nodes typically
include all components — both the control plane master components and the
node components — but are dedicated to running the control plane and to not
process any application workloads (typically by being tainted).
Other nodes are typically designated as worker nodes (or simply nodes) and only
include the node components.
2. Achieving scalability and availability
A common requirement is for a Kubernetes cluster to both scales to accommodate increasing workloads and to be fault-tolerant, remaining available even in the
presence of failures (datacenter outages, machine failures, network partitions).
Scalability and availability for the node plane Scalability and availability for the control plane
A cluster can be scaled by adding worker nodes, which increases the workload
capacity of the cluster, giving Kubernetes more room to schedule containers.
Kubernetes is self-healing in that it keeps track of its nodes and, when a node is
deemed missing (no longer passing heartbeat status messages to the master), the
control plane is clever enough to re-schedule the pods from the missing node onto
other (still reachable) nodes. Adding more nodes to the cluster therefore also
makes the cluster more fault tolerant, as it gives Kubernetes more freedom in
rescheduling pods from failed nodes onto new nodes.
Adding nodes to a cluster is commonly carried out manually when a cluster
administrator detects that the cluster is heavily loaded or cannot fit additional
pods.
Monitoring and managing the cluster size manually is tedious. Through the use of
AutoScaling, this task can be automated. The Kubernetes cluster-autoScaler is one
such solution. At the time of writing, it only supports Kubernetes clusters running
on GCE and AWS and only provides simplistic scaling that grows the cluster
whenever a pod fails to be scheduled.
With the AutoScaling engine, more sophisticated and diverse AutoScaling schemes
can be implemented, utilizing predictive algorithms to stay ahead of demand and
scaling not only to fit the current set of pods, but also taking into account other
cluster metrics such as actual CPU/memory usage, network traffic, etc.
Furthermore, the autoScaler supports a wide range of cloud providers and can
easily be extended to include more via our cloud pool abstraction. To handle node
scale-downs gracefully, a Kubernetes-aware cloud pool proxy is placed between
the autoScaler and the chosen cloud pool.
Adding more workers does not make the cluster resilient to all sorts of failures.
For example, if the master API server goes down (for example, due to its machine
failing or a network partition cutting it off from the rest of the cluster) it will no
longer be possible to control the cluster (via kubectl).
For a true highly available cluster, we also need to replicate the control plane
components.
Such a control plane can remain reachable and functional even in the face of
failures of one or a few nodes, depending on the replication factor.
A HA control plane setup requires at least three masters to withstand the loss of
one master, since etcd needs to be able to form a quorum (a majority) to continue
operating.
3. The anatomy of a HA cluster setup
Given the loosely coupled nature of Kubernetes’ components, a HA cluster can be realized in many ways, But generally there are a few common guidelines:
o We need a replicated, distributed etcd storage layer.
o We need to replicate the apiserver across several machines and front them with a load-balancer.
o We need to replicate the controllers and schedulers and set them up for leader-election.
o We need to configure the (worker) nodes’ kubelet and kube-proxy to access the apiserver through the LoadBalancer.
The replication factor to use depends on the level of availability one wishes to achieve. With three sets of master components the cluster can tolerate a failure of one
master node since, in that case, etcd requires two live members to be able to form a quorum (a node majority) and continue working. This table provides the fault-
tolerance of different etcd cluster sizes.
A HA cluster with a replication factor of three could be realized as illustrated in the following schematical image:
Some further considerations:
etcd replicates the cluster state to all master nodes. Therefore, to lose all data, all
three nodes must experience simultaneous disk failures. Although unlikely, one
may want to make the storage layer even more reliable by using a separate disk
that is decoupled from the lifecycle of the machine/VM (for example, an AWS EBS
volume).
You can also use a RAID setup to mirror disks, and finally set up etcd to take
periodical backups.
The etcd replicas can be placed on separate, dedicated machines to isolate and
give them dedicated machine resources for improved performance.
The load-balancer must monitor the health of its apiservers and only forward
traffic to live servers.
Spread masters across data centers (availability zones in AWS lingo) to increase
the overall uptime of the cluster. If the masters are placed in different zones, the
cluster can tolerate the outage of an entire availability zone.
(Worker) node kubelets and kube-proxys must access the apiserver via the load-
balancer to not tie them to a particular master instance.
The LoadBalancer must not become a single point of failure. Most cloud providers
can offer fault-tolerant LoadBalancer services. For on-premise setups, one can
make use of an active/passive nginx/HAProxy setup with a virtual/ floating IP that
is re-assigned by keepalived when failover is required.
4. Do I need a HA control plane?
So now that we know how to build a HA Kubernetes cluster, let’s get started. But wait, not so fast. Before heading on to build a HA cluster you may need to ask yourself:
do I really need a HA cluster?
A HA solution may not be strictly necessary to run a successful Kubernetes cluster. Before deciding on a HA setup, one needs to consider the requirements and needs of
the cluster and the workloads one intends to run on it.
One needs to take into account that a HA solution involves more moving parts and, therefore, higher costs.
A single master can work quite well most of the time. Machine failures in most clouds are quite rare, as are availability zone outages.
Can you tolerate the master being unreachable occasionally? If you have a rather static workload that rarely changes, a few hours of downtime a year may be
acceptable. Furthermore, a nice thing about the loosely coupled architecture of Kubernetes is that worker nodes remain functional, running whatever they were
instructed to run, even if masters go down. Hence worker nodes, in particular if spread over different zones can probably continue delivering the application service(s)
even when the master is down.
If you do decide to run a single master, you need to ensure that the etcd data is stored reliably, preferably backed up.
When we have deployed single-master Kubernetes clusters, we typically mount two disks to the master, one to hold the etcd data directory and the second disk to hold
snapshots. In this way, a failed master node can be replaced (make sure you use a static IP which you can assign to a replacement node!) and the etcd disk can be
attached to the replacement node. Also, on disk corruption, a backup can be restored from the backup disk.
In the end it’s a balancing act where you need to trade off the need to always have a master available against the cost of keeping additional servers running.
What tools do I use?
Say that you decide that your business-level objectives requires you to run a HA setup. Then it’s time to decide how to set up your cluster.
There are a bewildering number of options available, reflecting both that Kubernetes can run “anywhere” (clouds, hardware architectures, OSes, etc) and that there are
a lot of stakeholders that want to monetize.
One may opt for a hosted solution (“Kubernetes-as-a-Service”) such as Google Container Engine or Azure Container Service. These typically reduce the administrative
burden at the expense of higher costs, reduced flexibility, and vendor lock-in.
If you want to build a HA cluster yourself, there are many different options ranging from building your own from scratch (Kubernetes the hard way may lead you in the
right direction), to cloud-specific installers (like kops for AWS), to installers suitable for clouds and/or bare-metal scenarios (like kubespray and kubeadm).
A lot of factors affect which solution is right for you. Using an available installer allows you to benefit from the experience of others, with the risk of ending up with a
“black boxed” solution that is difficult to adapt to your needs. At the other extreme, building from scratch will be a serious investment in time which will give you full
insight and control over your solution, with the risk of repeating the same mistakes as others have already made.
References:
Kubernetes Design and Architecture
Building High-Availability Clusters
Eng. / Tarek Ali - MicroServices CI/CD & AWS Consultant.