Kubernetes Fundamentals - Container Orchestration & Deployment Flashcards

Question 1

What is Kubernetes?

Accepted Answer

Kubernetes (K8s) is an open-source container orchestration platform designed to automate the deployment, scaling, and management of containerized applications. It groups containers into logical units for easy management and discovery.

Question 2

Why is container orchestration necessary?

Accepted Answer

Container orchestration is necessary to manage the lifecycle of containers at scale. It automates tasks like deployment, scaling, networking, load balancing, health monitoring, and self-healing, which are complex and error-prone when done manually across many containers.

Question 3

Define a Kubernetes `Pod`.

Accepted Answer

A `Pod` is the smallest deployable unit in Kubernetes. It represents a single instance of a running process in your cluster. A `Pod` encapsulates one or more containers (which share storage, network, and a specification for how to run the containers), and resources for those containers.

Question 4

What is a Kubernetes `Deployment`?

Accepted Answer

A `Deployment` is a higher-level object that manages a set of identical `Pods`. It provides declarative updates for `Pods` and `ReplicaSets`, allowing you to define the desired state (e.g., number of replicas, container image) and Kubernetes will ensure that state is maintained.

Question 5

Explain the purpose of a Kubernetes `Service`.

Accepted Answer

A `Service` is an abstract way to expose an application running on a set of `Pods` as a network service. It provides a stable IP address and DNS name for a group of `Pods`, enabling other applications or users to access them reliably, even if `Pods` are created or destroyed.

Question 6

Describe a `ClusterIP` Service.

Accepted Answer

A `ClusterIP` `Service` exposes the `Service` on an internal IP address within the cluster. It's the default `Service` type and is only reachable from within the cluster. It's ideal for internal communication between different parts of your application.

Question 7

Describe a `NodePort` Service.

Accepted Answer

A `NodePort` `Service` exposes the `Service` on each Node's IP at a static port (the `NodePort`). This makes the `Service` accessible from outside the cluster by requesting `:`. It's suitable for development or simple external access.

Question 8

Describe a `LoadBalancer` Service.

Accepted Answer

A `LoadBalancer` `Service` exposes the `Service` externally using a cloud provider's load balancer. It automatically provisions an external IP address and load balances traffic to the `Pods` behind the `Service`. This is the standard way to expose internet-facing applications.

Question 9

What are Kubernetes `Namespaces`?

Accepted Answer

`Namespaces` are a way to divide cluster resources among multiple users or teams. They provide a scope for names, preventing naming collisions, and can be used to apply resource quotas and access control policies to a subset of resources.

Question 10

What is a Kubernetes `ConfigMap`?

Accepted Answer

A `ConfigMap` is an API object used to store non-confidential data in key-value pairs. It allows you to decouple configuration artifacts from image content to keep containerized applications portable. `ConfigMaps` can be consumed by `Pods` as environment variables, command-line arguments, or files in a volume.

Question 11

What is a Kubernetes `Secret`?

Accepted Answer

A `Secret` is an API object used to store sensitive data, such as passwords, OAuth tokens, and SSH keys. It's similar to `ConfigMaps` but is designed for confidential information and provides basic encoding (base64) and access control mechanisms.

Question 12

Explain Kubernetes `Volumes`.

Accepted Answer

A Kubernetes `Volume` is a directory, possibly with some data in it, that is accessible to the containers in a `Pod`. It provides persistent storage for containers, outliving the `Pod` itself (depending on the `Volume` type), and allows data to be shared between containers within the same `Pod`.

Question 13

What is Kubernetes `Ingress`?

Accepted Answer

`Ingress` exposes HTTP and HTTPS routes from outside the cluster to `Services` within the cluster. It provides external access to services with features like load balancing, SSL termination, and name-based virtual hosting, often managed by an `Ingress` controller.

Question 14

What is the role of `kube-apiserver`?

Accepted Answer

The `kube-apiserver` is the front-end for the Kubernetes control plane. It exposes the Kubernetes API, which is used by users, external components, and internal cluster components to communicate with the cluster. It validates and configures data for API objects.

Question 15

What is the role of `kube-controller-manager`?

Accepted Answer

The `kube-controller-manager` runs controller processes. Each controller (e.g., `Deployment` controller, `Service` controller) watches the shared state of the cluster through the API server and makes changes to move the current state towards the desired state.

Question 16

What is the role of `kube-scheduler`?

Accepted Answer

The `kube-scheduler` watches for newly created `Pods` with no assigned node and selects a node for them to run on. It considers various factors like resource requirements, hardware/software/policy constraints, affinity/anti-affinity specifications, and data locality.

Question 17

What is the role of `kubelet`?

Accepted Answer

`kubelet` is an agent that runs on each node in the cluster. It ensures that containers are running in a `Pod` and are healthy. It communicates with the `kube-apiserver` to receive `Pod` specifications and manages the `Pod`'s containers.

Question 18

What is the role of `kube-proxy`?

Accepted Answer

`kube-proxy` runs on each node and maintains network rules on the nodes. These rules allow network communication to your `Pods` from network sessions inside or outside of the cluster. It handles `Service` abstraction by forwarding traffic to the correct `Pods`.

Question 19

How do you list resources using `kubectl`?

Accepted Answer

Use `kubectl get` to list various Kubernetes resources.
Example:
```bash
kubectl get pods
kubectl get deployments -n my-namespace
kubectl get services --all-namespaces
```

Question 20

How do you deploy or update resources using `kubectl`?

Accepted Answer

Use `kubectl apply -f <filename.yaml>` to apply a configuration defined in a YAML file. If the resource already exists, it will update it; otherwise, it will create it.
Example:
```bash
kubectl apply -f my-deployment.yaml
```

Question 21

How do you delete resources using `kubectl`?

Accepted Answer

Use `kubectl delete` to remove resources. You can specify the resource type and name, or use a YAML file.
Example:
```bash
kubectl delete pod my-pod
kubectl delete deployment my-app -n my-namespace
kubectl delete -f my-deployment.yaml
```

Question 22

How do you get detailed information about a resource using `kubectl`?

Accepted Answer

Use `kubectl describe ` to get detailed information about a specific resource, including its status, events, and associated resources. Example: ```bash kubectl describe pod my-pod-xyz kubectl describe service my-service ```

Question 23

How do you view logs from a container in a Pod using `kubectl`?

Accepted Answer

Use `kubectl logs <pod_name>` to retrieve logs from a container within a `Pod`. You can specify a container name if there are multiple in the `Pod`.
Example:
```bash
kubectl logs my-app-pod-123
kubectl logs my-app-pod-123 -c my-container-name
```

Question 24

How do you execute a command inside a container using `kubectl`?

Accepted Answer

Use `kubectl exec -it -- ` to execute a command inside a running container. The `-it` flags provide interactive terminal access. Example: ```bash kubectl exec -it my-app-pod-123 -- /bin/bash kubectl exec my-app-pod-123 -- ls /app ```

Kubernetes Fundamentals - Container Orchestration & Deployment

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