What is
Kubernetes(k8s)?
Kubernetes is an opensource
container orchestration tool for building a fault-tolerant, scalable platform
designed to automate and centrally manage containerized applications.The
platform itself can be deployed within almost any infrastructure – in the local
network, server cluster, data center, any kind of cloud public (Google Cloud,
Microsoft Azure, AWS, etc.), private, hybrid, or even over the combination of
these methods.
What is Docker?
Docker is a containerization
platform that packages your application and all its dependencies together in
the form of a docker container to ensure that your application works seamlessly
in any environment.
What is
Container?
Docker Container is a standardized
unit which can be created on the fly to deploy a particular application or
environment. It could be an Ubuntu container, CentOs container, etc. to
full-fill the requirement from an operating system point of view. Also, it
could be an application oriented container like CakePHP container or a
Tomcat-Ubuntu container etc.
Kubernetes
Architecture components?
K8s Master server has,
API-Server :
Performs all the administrative
tasks through the API server within the master node.In this REST commands are
sent to the API server which validates and processes the requests.After
requesting, the resulting state of the cluster is stored in the distributed
key-value store.
Controller :
It is a daemon which regulates the
Kubernetes cluster which manages the different non-terminating control loops.It
watches the desired state of the objects it manages and watches their current
state through the API server. If the current state of the objects it manages
does not meet the desired state, then the control loop takes corrective steps to
make sure that the current state is the same as the desired state.
Scheduler:
The scheduler schedules the tasks to
slave nodes. It stores the resource usage information for each slave node.It
schedules the work in the form of Pods and Services.
etcd(Key-value store) : etcd is
a distributed key-value store which stores the cluster state. etcd is written
in the Go programming language.It is also used to store configuration details
such as subnets, ConfigMaps, Secrets, etc
K8s Node has,
Kubelet:
It is an agent which communicates
with the Master node and executes on nodes or the worker nodes. It gets the Pod
specifications through the API server and executes the containers associated
with the Pod and ensures that the containers described in those Pod are running
and healthy.
Kube-proxy:
It is the network proxy which runs
on each worker node and listens to the API server for each Service endpoint
creation/deletion.For each Service endpoint, kube-proxy sets up the routes so
that it can reach to it.
How Kubernetes works?
You have written an application and
you used docker as a platform to containerised it. now if you want to run that
application, you need to define the docker image in a YAML file and Kubernetes
consider that YAML file and created pod(s) for the docker image. pods are group
of containers that runs in a shared context. Kubernetes take the request from
Application Load Balancer and transfers it to respective nodes and nodes having
pods which are containers and application runs on container and generates the
result and that result is transferred back to kubernetes and the result is
given back to the client.
What are the features
of Kubernetes?
1.Service Discovery and load
balancing
2.Auto Scaling
3.Self Repair
4.Storage Orchestration
5.Deployments and Automatic
Rollbacks
6.Configuration Management and
Secrets
7.Batch execution
Kubernetes GUI?
Kubernetes Dashboard provide web-based Kubernetes user
interface. You can use Dashboard to deploy containerized applications to a
Kubernetes cluster, troubleshoot your containerized application, and manage the
cluster resources.
Kubernetes monitoring
tools?
1.Kubelet
2.cAdvisor
3.Kube-state-metrics
4.Kubernetes Dashboard
5.Prometheus
6.Jaeger
7.Kubewatch
8.Weave Scope
9.EFK Stack
Kubernetes
alternatives?
1.Docker swarm
2.Rancher
3.Apache Mesos
4.Docker Compose
More are there.
What are the
difference between Kubernetes and docker swarm?
|
Sl.no
|
Description
|
Docker Swarm
|
Kubernetes
|
|
1
|
Developed By
|
Docker Inc
|
Google
|
|
2
|
Year Released
|
2013
|
2014
|
|
3
|
Companies using
|
Bugsnag, Bluestem Brands, Hammerhead, Code Picnic,
Dial once etc.
|
Asana, Buffer, CircleCI, Evernote, Harvest, Intel,
Starbucks, Shopify etc.
|
|
4
|
Controller
|
Manager
|
Master
|
|
5
|
Storage
|
Volumes
|
Persistent and Ephermal
|
|
6
|
Public Cloud Service Provider
|
Google, Azure, AWS, OTC
|
Azure
|
|
7
|
Compatibility
|
Less Extensive and Customizable
|
More Extensive and highly customizable
|
|
8
|
Installation
|
Easy to set up
|
Takes time for installation
|
|
9
|
Tolerance ratio
|
Low Fault Tolerance
|
High fault tolerance
|
|
10
|
Large Clusters
|
Speed is considered for the strong cluster states
|
Provides container deployment and scaling even in large
clusters without considering the speed
|
|
11
|
Load Balancing
|
Provides load balancing when pods in the container are
defined as service
|
Provides automated internal load balancing through any
node in the cluster
|
|
12
|
Deployment unit
|
Task
|
Pod
|
|
13
|
Port
|
Published Port
|
Endpoint
|
|
14
|
Network
|
Overlay
|
Flat Networking space
|
|
15
|
Community
|
Active user base that regularly updates images for various
application
|
Enjoys strong support from open source communities and big
companies like Google, Amazon, Microsoft, and IBM
|
|
16
|
Weakness
|
No certification plan for vendors. Most
organisation need commercially certified version
|
Inclined towards developers than central IT
|
|
17
|
Strengths
|
Mostly controlled by a single vendor who can decide
product direction
|
Clear market leader; largest adoption and interest
|
|
18
|
Slave
|
Worker
|
Nodes
|
|
19
|
Container set up
|
Functionality is provided and limited by Docker API
|
Client API and YAML are unique in kubernetes
|
|
20
|
Scalability
|
Quick container deployment and scaling even in large
containers
|
Provides strong guarantees to the cluster states at
expense of speed
|
References:
Post a Comment