Kubernetes for Beginners: An Introductory Guide
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Kubernetes is an open-source tool for managing containerized workloads and services. It allows for deploying, maintaining, and scaling applications across clusters of servers. Kubernetes operates at the container level to automate tasks like deployment, availability, and load balancing. It uses a master-slave architecture with a master node controlling multiple worker nodes that host application pods, which are groups of containers that share resources. Kubernetes provides benefits like self-healing, high availability, simplified maintenance, and automatic scaling of containerized applications.
Kubernetes for Beginners: An Introductory Guide
- 1. What is Kubernetes? A Beginners’ Guide
- 2. Both are essentially structures for storing and running applications. ● Virtual Machines (VMs) - Isolated at hardware level, higher resource usage. ● Containers - Slightly less isolated, leaner and faster. ○ Docker has ~95% market share in containerisation technology. Virtualisation Technologies - VMs vs. Containers
- 3. Virtualisation Technologies - VMs vs. Containers
- 4. ● Because containers are so lean, you can have a huge number of them on a single server. They allow large monolithic applications to be split into many microservices. ● Each microservice has its own container & controls one feature of the application. ○ Benefit: This is an efficient use of resources & can save on hosting costs compared to VMs. ○ Problem: How do you manage, rollout, rollback, maintain and repair such a large number of containers? ● The solution: Kubernetes You can have 1000’s of containers on a server
- 5. ● Kubernetes (K8S) is an open source software tool for managing containerised workloads. ● It operates at the container (not hardware) level to automate the deployment, scaling and management of applications. ● K8s works alongside a containerisation tool, like Docker. So if containers are the ‘ingredients’ of an application, then K8S would be the ‘chef’. ● As well as managing individual containers, K8s can also manage clusters. ○ A cluster is a series of servers connected to run containers. ○ K8s can scale up to 5,000 servers and 150,000 pods in a single cluster. ○ A pod is a group of containers that share resources, a network and can communicate with one another. Kubernetes: Definition
- 6. How Does Kubernetes Work? 1. Worker Nodes (slave) - This is where containers are deployed. These nodes contain: a. Multiple pods b. Docker engine c. Any add-ons e.g. DNS d. Kubelet - this is an important component as it carries out the instructions from the master node. 2. Master Node (master) - This controls the deployment. This node contains: a. API server - this receives inputs from the User Interface (UI) or Command Line Interface (CLI). b. Controller - uses information from the API to drive the application from its current state towards the desired state provided. c. Scheduler d. Etcd - handles configuration management, service discovery etc. Kubernetes has a master-slave architecture:
- 7. Kubernetes Architecture To make the last slide easier to visualise, here is a diagram of the architecture: Nodes 1-n (in purple) are the worker nodes.
- 8. ● Remembering the specific components and their roles isn’t important here. ● The architecture has just been outlined to give some background on how Kubernetes is able to orchestrate containers at scale. ● Whilst initially the idea of Kubernetes sounds quite simple, seeing the architecture shows that is is actually fairly complex to work with. ● This is why Bytemark want to offer a managed Kubernetes service - so our customers can get the benefits of Kubernetes without worrying about managing and maintaining everything themselves. Kubernetes Architecture
- 9. ● Self-healing ○ Clusters can auto-restore from errors by rolling back to the last working version of software. This allows teams to ship quickly without the risk of breaking anything. ● High Availability ○ Clusters can be recreated on a working node to avoid downtime during server failure. ● Simplifys Maintenance ○ If a server needs to be rebooted, or the host OS needs updating, containers can be moved to another node whilst maintenance is carried out. ● Automatic Scaling ○ Uses information from user requests and CPU usage to increase or decrease the number of nodes running to match demand. ● Efficient ○ Automatically spins up any new containers on under-utilized nodes. Benefits of Kubernetes
- 10. There are sometimes misconceptions about what Kubernetes can do. Kubernetes does not… ● Provide any comprehensive machine configuration. ● Provide a configuration language/system ● Dictate logging, monitoring or alerting solution ● Build your application ● Provide middleware, data-processing frameworks, databases, caches etc. BUT these components can run on Kubernetes Things Kubernetes does not do...
- 11. ANY QUESTIONS? ● To learn more about Kubernetes at Bytemark, contact [email protected]