Kubernetes Basics Flashcards
Annotation
arbitrary, non-identifying metadata for retrieval by API clients such as tools and libraries. Beta API functionality may be activated by setting specific annotations.
Cluster
an aggregate group of nodes configured to run a functioning Kubernetes system. Nodes can be a mix of physical or virtual machines running on public or private clouds, or even in on-premise data centers. This term refers to the aggregate of all nodes and not individual nodes.
Deployment
a declarative template for creating and scaling pods.
k8s
an abbreviation for Kubernetes. This is commonly used in documentation and naming things.
Label
key/value pairs attached to objects such as pods. Labels specify identifying attributes meaningful to users but do not imply semantics to Kubernetes. Here’s an example: your environment may be set to production.
Name
a unique identifier for a particular resource.
Namespace
a group of unique names.
Pod
a group of one or more containers running on a single node.
Replica Set
coordinates pod creation, deletion, and updates during deployments.
Request
the desired amount of CPU or memory for a container in a pod.
Resource
any individual Kubernetes item such as deployment, pod, service, or secret, etc.
Service
a networking abstraction that defines rules on how to access pods determined by a selector. Do not confuse this concept with things like back-end service or application. Kubernetes services are about networking.
Secret
sensitive information, such as passwords, OAuth tokens, and ssh keys.
Selector
a set of rules to match resources based on metadata.
StatefulSet
a pod with guarantees on deployment and scaling order.
Volume
a stateful block store for use with ephemeral pods.
True or False: Volumes may have multiple back-ends such as on-disk, GCE, persistence disks, or other third party systems
True: Do not confuse this with a database. A volume is simply a place to write persisted data.
True or False: Nodes can be a mix of physical or virtual machines running on public or private clouds, or even in on-premise data centers.
True. Nodes belong to a “cluster,” which refers to the aggregate of all nodes and not individual nodes.
True or false, a Kubernetes “Service” refers to a deployment offering a service such as database, web hosting, data processing, etc?
False. A Kubernetes Service is a networking abstraction that defines rules on how to access pods determined by a selector. Kubernetes services are about networking.
Add-ons
Resources that extend the functionality of Kubernetes.
Admission Controller
A piece of code that intercepts requests to the Kubernetes API server prior to persistence of the object.
API Group
A set of related paths in Kubernetes API.
API Server
Also known as:kube-apiserver
The API server is a component of the Kubernetes control plane that exposes the Kubernetes API.
True or False: The API server is the front end of the Kubernetes control plane.
True: The API server is the front end for the Kubernetes control plane and is the main implementation of the Kubernetes API.
True or False: It is best practice to scale the Kubernetes API server vertically? (Larger servers)
False: Kubernetes API servers are designed to scale horizontally (more servers) and balance between the servers.
App container
Application containers (or app containers) are the containers in a pod that are started after any init containers have completed.
Application Architect
A person responsible for the high-level design of an application.
Application Developer
A person who writes an application that runs in a Kubernetes cluster.
Applications
The layer where various containerized applications run.
Approver
A person who can review and approve Kubernetes code contributions.
Certificate
A cryptographically secure file used to validate access to the Kubernetes cluster.
cgroup (control group)
A group of Linux processes with optional resource isolation, accounting and limits.
CIDR - Is an abbreviation for…
Classless Inter-Domain Routing
CIDR - Is…
a notation for describing blocks of IP addresses and is used heavily in various networking configurations.
glossary is found at
https://kubernetes.io/docs/reference/glossary/?all=true
ConfigMaps
Kubernetes resource that is used to decouple configuration artifacts from image content to keep containerized applications portable
Headless Service
a Kubernetes service resource that won’t load balance behind a single service IP.
How does a Headless service operate?
returns a list of DNS records that point directly to the pods that back the service.
How is a headless service defined?
by declaring the clusterIP property in a service spec and setting the value to None.
True or false: StatefulSets require a headless service to identify pods in the cluster network?
True.
Stateful Sets
manage the deployment and scaling of pods given a container spec.
How do Stateful Sets differ from Deployments?
Stateful sets are not interchangeable. Each pod in a StatefulSet has a persistent identifier that it maintains across any rescheduling.
