1 - Kubernetes Overview Flashcards
How is kubernetes also known?
K8s
Who created the Kubernetes technology?
What is Kubernetes ?
It is a container orchestration technology.
What is Matrix from Hell ?
It is when various technologies that are part of a project depend on operating systems, different libraries and come into conflict generating problems when it comes to developing, testing and deploying.
What are Containers ?
They are completely isolated environments. They can have their own processes or services, their own network interfaces, etc.
They are similar to virtual machines except that they share the host kernel.
How many layers does an operating system consist of? And what are these layers?
- OS Kernel ->Responsible for interacting with the adjacent hardware.
- Software -> It is what differentiates one distribution from another.
Imagine an Ubuntu OS installed on a server, what other distributions can we run as a docker in this environment?
We can run any distribution that has the same kernel, for example: Fedora, Debian, SUSE, CentOS and etc.
But we cannot run a Windows server, as they do not share the same kernel.
What is the main purpose of containers?
The main purpose of containers is to containerize applications, send and run them.
What are the differences between containers and virtual machines?
Virtual machine
- Application
- Libraries and Dependencies
- Virtual Machine Operating System
- Hypervisor
- Host Operating System
- Hardware Infrastructure
Container
- Application
- Libraries and Dependencies
- Docker
- Host Operating System
- Hardware Infrastructure
What are the advantages of containers over traditional machines?
- Lower CPU resource utilization
- Use of smaller disk space
- Boot time of a smaller container
What are container images?
Images are packages or templates that are used to run the containers. An image is a set of software used to run a container with a certain characteristic.
What is Orchestration ?
It is the process of automatic deployment and management of containers. Increase and decrease the scalability of the environment according to its use, as well as, detect, repair and keep the environment running smoothly.
What are the main orchestrators available on the market?
- Docker Swarm -> Some advanced features needed for complex applications are missing
- Kubernetes -> Easier to set up and start using than Mesos and offers many advanced options for complex environments.
- Mesos -> Difficult to configure and start using, but it supports complex environments.
What cloud providers support Kubernetes?
- AWS
- GCP
- Azure
What are the principal advantage of use Orchestration ?
- High Availability
- Load Balancing
What is a Node ?
Nodes are virtual or physical machines that have Kubernetes installed.
A node is a working machine where the containers run. In the past, nodes were also known as minions.
What is a Cluster ?
Cluster is a set of nodes grouped together.
What is a Master ?
It is a node installed and configured to be a master.
Responsible for managing the cluster, it stores information about the cluster members and how the nodes should be monitored.
Responsible for the orchestration of the other nodes.
What are the components of a Kubernetes installation ?
- API Server
- etcd keystore
- kubelet
- Container Runtime
- Controller
- Scheduller
What is the purpose of API Server ?
The API Server is responsible for interacting with the user and uses commands to do this.
What is the purpose of etcd keystore service ?
It is a trusted, distributed key-value store used to store data used to manage the cluster.
What is the purpose of kubelet service ?
It runs on each node in the cluster and is responsible for ensuring that containers are running on nodes as expected.
What is the purpose of Container Runtime ?
Container Runtime is the software responsible for executing the containers.
What is the purpose of Scheduller ?
The scheduler is responsible for distributing work or containers across multiple nodes. It looks for newly created containers and assigns them to the node.
What is the purpose of Scheduler ?
The scheduler is responsible for distributing work or containers across multiple nodes. It looks for newly created containers and assigns them to the node.
Which components run on a worker node and a Master node?
Worker
- Container Runtime
- kubelet
Master
- kube-apiserver
- etcd
- Controller
- Scheduler
What is the name of the utility that is used to send commands to kube-apiserver?
kubectl
