Cloud computing is one of the in-demand and growing domains of the IT industry. A certification in any of the cloud computing courses will help you upgrade your profile’s value in the job industry. It is not easy to get a job in the fast-paced IT industry. A candidate needs to prepare well to crack any interview process in the technology industry.
Kubernetes is one of the trending and newest cloud computing technology in which the scope is highly bright and sparkling. But, clearing the interview round is not a cup of tea. Do you also get a little nervous before going for an Interview? It is obvious to feel nervous and get hesitated before going for an interview.
To help you to crack the interview round we are here with some top Kubernetes Interview Questions and Answers. Therefore, keep reading the blog till the end.
1. What is Kubernetes?
Kubernetes is one of the newest trends in cloud computing technologies. Kubernetes is an open-source technology that helps in scheduling and executing application containers inside and outside clusters. A Kubernetes cluster mainly comprises two types of resources: Master and Nodes.
- Master:- The master helps to coordinate all the activities in the cluster. It includes activities such as scheduling, maintaining, and upgrading the applications of a system software or application.
- Node:- A node is an example of an Operating System (OS) that serves as a worker machine in a Kubernetes cluster.
- Further, Node consists of two components which are described below:-
- Kubelet: Mastering the agent by managing and communicating it.
- Tool: Tools for operating container operations.
2. What are the basic principles of Kubernetes?
The basic principles of Kubernetes are described below:-
- Kubernetes Basics
- Kubernetes Networking
- Kubernetes Storage
- Advanced Kubernetes Scheduling
- Kubernetes Administration and Maintenance
- Kubernetes Troubleshooting
- Kubernetes Security
3. Explain the basic principles of Kubernetes.
The basic principles of Kubernetes are as follows:-
- Kubernetes Basics:- Kubernetes Basics helps to provide a solid foundation for understanding the core concepts and principles of the powerful container such as the orchestration platform.
- Kubernetes is created to automate the deployment, scaling, and management of containerized applications. It also offers a wide range of features and functionalities that enable efficient resource utilization, high availability, and fault tolerance.
- Kubernetes can abstract away the underlying infrastructure, allowing developers to focus on building and deploying applications without worrying about the specific details of the underlying infrastructure.
- Kubernetes Networking:- Furthermore, Kubernetes Administration involves managing various components and resources within the cluster. Administrators need to configure and manage nodes, which are the individual machines that make up the cluster. This includes tasks such as provisioning new nodes, monitoring their health, and managing their capacity. Additionally, administrators need to manage the deployment and scaling of applications within the cluster. This involves creating and managing pods, which are the smallest units of deployment in Kubernetes. Administrators also need to manage services, which provide networking and load-balancing capabilities for applications running in the cluster.
- Kubernetes Networking helps to provide you with an understanding of the networking concepts in detail. It will also help you understand POD networking concepts, CNI in Kubernetes, DNS and IP Address Management, service networking and load balancer. Therefore, this is another basic principle of Kubernetes.
- Kubernetes Storage:- Kubernetes Basics also involve understanding how to configure and manage networking in a Kubernetes cluster. Kubernetes provides a flexible networking model that allows pods to communicate with each other and with external services. This is achieved through the use of network plugins, which enable the creation of virtual networks and routing rules within the cluster.
- In addition to networking, security is another important aspect of Kubernetes Basics. Kubernetes offers various mechanisms for securing applications and protecting sensitive data. This includes features such as role-based access control (RBAC), which allows fine-grained control over who can access and perform actions within the cluster. Kubernetes also supports the use of secrets for securely storing sensitive information, such as passwords or API keys.
- Advanced Kubernetes Scheduling:- Advanced Kubernetes Scheduling is a topic that delves into the intricate mechanisms of how Kubernetes manages the allocation and placement of workloads on its cluster. It involves the utilization of various scheduling policies, such as affinity and anti-affinity rules, node selectors, and resource constraints, to ensure optimal resource allocation and workload distribution.
- In simpler terms, Advanced Kubernetes Scheduling explores the advanced techniques used by Kubernetes to efficiently assign tasks to nodes in a cluster. By considering factors like workload requirements, node availability, and resource utilization, Kubernetes can intelligently schedule workloads to maximize performance and minimize downtime.
- With Advanced Kubernetes Scheduling, administrators can fine-tune their cluster’s scheduling behaviour to meet specific requirements and optimize resource utilization. This can result in improved application performance, reduced resource wastage, and better overall cluster efficiency.
- Kubernetes Administration and Maintenance:- Kubernetes Administration and Maintenance require a strong understanding of the underlying architecture and concepts of Kubernetes. Administrators need to be familiar with the control plane components, such as the API server, controller manager, and scheduler, which are responsible for managing and orchestrating the cluster. They also need to understand how to configure and manage the etcd data store, which stores the cluster’s state.
- In terms of maintenance, administrators should regularly monitor the cluster’s logs and metrics to identify any issues or performance bottlenecks. They can use tools like Prometheus and Grafana to gather and visualize these metrics, allowing them to proactively address any potential problems. Administrators should also regularly review and update their cluster’s security policies to ensure that it remains protected against potential threats.
- Kubernetes Troubleshooting:- The procedure of identifying, diagnosing, and resolving problems in Kubernetes clusters, nodes, pods, or containers is known as Kubernetes Troubleshooting. Kubernetes troubleshooting is another basic principle that helps you learn to operate the system software of cloud technologies by analyzing the problems in Kubernetes containers and pods.
- Kubernetes Security:- Kubernetes Security enables you to implement strong network segmentation and isolation to minimize the impact of a security breach. Kubernetes Security also enables to conduct regular security audits and assessments to identify any vulnerabilities or misconfigurations.
- Some of the other features of Kubernetes Security are given below:
- To enforce least-privilege access controls to restrict access to sensitive resources.
- To implement and secure container runtime environments to protect against malicious code execution.
- To regularly review and update security policies and procedures in line with industry standards and best practices.
- Therefore, Kubernetes Security is one of the other basic principles or subjects of Kubernetes.
4. How are Docker and Kubernetes related?
Docker and Kubernetes are both technologies used in the world of containerization. Docker is a tool used to create, deploy, and run applications in containers, while Kubernetes is a container orchestration tool used to manage and scale applications deployed in containers. In other words, Docker creates the containers, and Kubernetes manages them. Together, they provide a powerful platform for developing, deploying, and managing container-based applications.
5. Explain the features of Kubernetes.
The features of Kubernetes are as follows:-
- Kubernetes places control for the user where the server will host the container. It will control how to launch. So, Kubernetes automates various manual processes.
- Kubernetes manages various clusters at the same time.
- It provides various additional services like management of containers, security, networking, and storage.
- Kubernetes self-monitors the health of nodes and containers.
- With Kubernetes, users can scale resources not only vertically but also horizontally too easily and quickly.
6. What is a node in Kubernetes?
The smallest fundamental unit of computing hardware is known as Node in Kubernetes. In Kubernetes, a node is a physical or virtual machine that is part of a Kubernetes cluster. It is responsible for running containers and providing the necessary resources, such as CPU, memory, and storage, to support them. Each node has its unique IP address and is assigned a set of labels that are used to identify it and group it with other nodes. Nodes communicate with the Kubernetes master to receive instructions on which containers to run and how to manage them.
7. What are K8s?
K8s is another name used for Kubernetes.
8. What is the main difference between the Docker Swarm and Kubernetes?
The main difference between the Docker Swarm and Kubernetes are as follows:-
Docker Swarm is an open-source container orchestration platform that is built and handled by Docker. Docker Swarm helps to convert multiple Docker instances into a single virtual host. A Docker Swarm cluster generally consists of three items:
- Services and Tasks
- Load balancers
One of the main advantages of Docker Swarm is that it is lightweight and easy to use. It also takes less time to understand than more complex orchestration tools. It works with the Docker CLI, so there is no need to install the entire new CLI. Moreover, it works seamlessly with existing Docker tools such as Docker Compose.
Kubernetes is an open-source container orchestration platform that was initially designed by Google to manage its containers. It has a more complex cluster structure than Docker Swarm. It usually has a builder and worker nodes architecture divided further into pods, namespaces, config maps, and so on. There are innumerable benefits of Kubernetes which are as follows:-
- It offers a large open-source community.
- It helps to support each operating system.
- It helps to manage large architectures and complex workloads.
- It supports building and monitoring a wide range of available integrations.
- Kubernetes is offered by all three key cloud providers: Google, Azure, and AWS.
9. What are the main components of Kubernetes architecture?
Below described are the main components of Kubernetes architecture:-
- Master Node: The main role of the Master Node is to manage the cluster and to provide the API that is responsible to manage the resources inside the Kubernetes cluster.
- Worker Node: They are used to handle and operate the containerization applications and networks to ensure that traffic between applications across the cluster and from outside of the cluster can be properly facilitated.
10. What is the role of Kube-apiserver?
The role of Kube-apiserver is described below:-
Kube-apiserver helps to validate and provide configuration data for the API objects. It further includes pods, services, and replication controllers.
Kube-apiserver helps to provide rest operations and also the front end of the cluster. This frontend cluster state is shared through which all other component interacts.
11. What process run on Kubernetes Master Node?
The process that runs on Kubernetes Master Node are as follows:-
- Controller Manager
- API Servers
12. What is a cluster of containers in Kubernetes?
A cluster of containers is a set of machine elements that are known as nodes. Clusters initiate specific routes so that the containers running on the nodes can communicate with each other. In Kubernetes, the container engine also provides hosting for the API server.
13. What is 'Heapster' in Kubernetes?
A Heapster is a performance monitoring and metrics collection system or tool used for data collection by the Kublet. This aggregator is natively supported and runs like any other pod within a Kubernetes cluster, which allows it to discover and query usage data from all nodes within the cluster.
14. What is a Namespace in Kubernetes?
The systematic format to arrange or organize the clusters into digital sub-clusters is known as Namespace in Kubernetes. It further helps to provide a mechanism for combining various groups of resources within a single cluster.
15. What is the Kubernetes controller manager?
A Kubernetes controller manager is responsible for managing and controlling the loops, garbage collection and namespaces creation. They are also responsible to run multiple processes on the master node.
16. What are the types of controller managers?
The primary types of controller managers are as follows:-
- Endpoints Controller
- Service Accounts Controller
- Namespace Controller
- Node Controller
- Token Controller
- Replication Controller
17. What are the different services within Kubernetes?
The different services within Kubernetes are as follows:-
- Node Port service
- External Name Creation service
- Cluster IP service
- Load Balancer service
18. What is the Load Balancer in Kubernetes?
A Load Balancer in Kubernetes is a component that distributes incoming network traffic across multiple instances of an application or service. It helps to distribute the workload and ensure the higher availability and scalability of the application.
The load balancer acts as a single entry point for customers, forwarding requests to backend models based on a predefined algorithm, such as round-robin or least connection. This helps to optimize resource utilization and enhance the overall performance of the application.
In Kubernetes, load balancing can be accomplished through various tools, such as using an external load balancer, deploying an internal load balancer service, or operating the built-in load balancing capabilities of the Kubernetes platform.
19. What do you understand by cloud controller manager?
The cloud controller manager is a Kubernetes component that manages the core controllers that are responsible for managing different aspects of the cloud infrastructure, such as nodes, routes, services, and volume claims. It acts as an interface between the Kubernetes control plane and the cloud provider’s APIs, allowing Kubernetes to manage resources on the cloud provider’s infrastructure.
20. What is a headless service?
A headless service in Kubernetes is a service that does not have a cluster IP assigned to it. Instead, it returns the IP addresses of the individual Pods that are part of the service. This is useful for services that need direct access to the Pods, such as stateful applications that require stable network identities.
21. What is kubelet?
Kubelet is a fundamental component of Kubernetes, an open-source container orchestration platform. It is responsible for managing and maintaining containers running on a node within a Kubernetes cluster.
At its core, Kubelet acts as an agent that runs on each node in the cluster and communicates with the Kubernetes control plane. Its primary function is to ensure that the containers defined in the cluster’s pod specifications are running and healthy.
Here are some key features and responsibilities of Kubelet:
- Pod Management: Kubelet is responsible for managing the lifecycle of pods on a node. It receives pod specifications from the Kubernetes API server and ensures that the specified containers are running within the pod. It monitors the health of containers and restarts them if necessary.
- Container Runtime Interface (CRI): Kubelet interacts with the container runtime, which is responsible for starting and managing containers. The CRI allows Kubelet to work with different container runtimes like Docker, containers, or CRI-O.
- Resource Management: Kubelet monitors the resource usage of containers on a node and enforces resource constraints defined in pod specifications. It ensures that containers have access to the required CPU, memory, and other resources.
22. Name the initial namespaces from which Kubernetes starts.
- Kube – system
- Kube – public
23. What is Kube-proxy?
Kube-proxy is a network or web proxy that drives on each node in a Kubernetes cluster. It helps to maintain network rules on the nodes, as well as load balance traffic between different pods in the cluster.
24. How can you get a static IP for a Kubernetes load balancer?
To obtain a static IP for the ingress-nginx-controller, just put it behind a Service of Type=LoadBalancer. Then, update or edit the ingress regulator so that it adopts the static IP of the Service by handing the publish-service flag.
25. How do we control the resource usage of POD?
To control the resource usage of a Pod, you can use resource requests and limits. Resource requests specify the minimum amount of resources that a Pod needs to run, while resource limits define the maximum amount of resources that a Pod can consume. By setting these values appropriately, you can effectively manage the resource allocation for your Pods. Additionally, you can also use resource quotas to limit the total amount of resources that can be consumed by a set of Pods or namespaces. These mechanisms help ensure that Pods does not exceed their allocated resources and prevent resource contention within your cluster.
26. What is PDB (Pod Disruption Budget)?
- A Pod Disruption Budget (PDB) is a component in Kubernetes that allows you to define policies for the disruption of pods during cluster functions. It helps ensure the availability and stability of your application by specifying the number of pods that can be simultaneously unattainable.
- PDBs are useful in scenarios where you like to perform supervision tasks on your cluster, such as upgrading nodes or draining a node for maintenance, without causing excessive downtime or service troubles. By setting a PDB, you can specify the lowest number of pods that must be available at any given time, ensuring that the disruption caused by these operations is controlled and within adequate limits.
27. How to monitor the Kubernetes cluster?
- The simple solution to monitor your Kubernetes cluster is by using a combination of Heapster to gather metrics, InfluxDB to keep it in a time series database, and Grafana to deliver and aggregate the collected information.
28. Why should namespaces be used? How does using the default namespace cause problems?
- Namespaces are used in programming languages to manage and organize code elements such as classes, functions, and variables. They provide a way to avoid naming conflicts and make code more modular and maintainable.
- Here are some reasons why namespaces should be used:
- Avoiding Naming Conflicts: When numerous libraries or modules are used in a project, there might be a chance of having the same name for other elements. Namespaces help prevent naming disputes by providing a unique identifier for each code element.
- Code Organization: Namespaces allow developers to logically group related code elements together. This makes it easier to navigate and understand the codebase, especially in larger assignments.
- Modularity and Reusability: By using namespaces, you can encapsulate code elements within a specific namespace, making them more modular and reusable. This promotes better code organization and helps in code maintenance and updates.
- Collaboration: When working on a project with multiple developers, namespaces help in avoiding disputes between different parts of the codebase. Each developer can work within their designated namespace without meddling with others’ work.
- Using the default namespace can cause several problems:
- Naming Collisions: If the default namespace is used without proper organization or qualification, there is a higher probability of naming collisions. This can lead to unpredictable behaviour or errors when different code elements have the same name.
- Code Clutter: Without using namespaces, all code elements reside in the same global namespace. This can result in a cluttered and unorganized codebase, making it difficult to comprehend and maintain.
- Difficulty in Identifying Dependencies: When using the default namespace, it becomes harder to identify dependencies between different parts of the codebase. This can make it challenging to track down issues or make changes without unintended side effects.
29. What is GKE?
GKE refers to Google Kubernetes Engine, which is used for controlling and orchestrating systems for Docker containers. Through Google Public Cloud, you can effortlessly orchestrate the container cluster.
30. How to troubleshoot if the POD is not getting scheduled?
If your POD is not getting scheduled, there are several troubleshooting measures you can take to identify and resolve the issue. Here are some suggestions:
- Check the status of your POD: Use the kubectl get pods command to inspect the status of your POD. If the POD is pending, it means it is not getting scheduled.
- Inspect the events: Run kubectl describe pod <pod-name> to view the events associated with your POD. Look for any error notifications or warnings that might provide an understanding of why the scheduling is failing.
- Verify resource requirements: Ensure that your POD’s resource requests and limits are properly configured. If your POD requires more resources than are available on your cluster, it may not get scheduled.
- Check node availability: Verify that there are sufficiently available nodes in your cluster to schedule your POD. Utilize the kubectl get nodes command to view the status of your nodes.
- Taints and tolerations: Check if any taints have been applied to your nodes and ensure that your POD has appropriate tolerations configured. Taints can prevent certain PODs from being scheduled on specific nodes.
- Node selectors and affinity rules: Review any node pickers or affinity rules specified in your POD’s configuration. Confirm they match the labels on your nodes correctly.
- Check for resource constraints: If your cluster is running low on resources such as CPU or memory, it may impact scheduling. Monitor resource utilization and believe in scaling up your cluster if necessary.
- Check for network issues: Network connectivity problems can also prevent a POD from being scheduled. Confirm that the network configuration is accurate and that all required ports are obtainable.
- Review admission controllers: If you have custom admission controllers enabled, they may be stopping the scheduling of your POD. Disable them temporarily to see if it fixes the issue.
- Check for pod disruption budgets: If you have configured a pod trouble budget for your POD, ensure that it is not discouraging the scheduling due to constraints.
31. What is Ingress Default Backend?
- Ingress Default Backend is a concept in Kubernetes that refers to the default behaviour of an Ingress controller when there are no matching rules for incoming requests.
- In Kubernetes, an Ingress controller acts as a reverse proxy and load balancer, routing incoming traffic to different services within the cluster based on the rules defined in the Ingress resource. These rules typically specify hostnames, paths, and other criteria for routing requests to specific services.
- However, there may be cases where an incoming request does not match any of the defined rules in the Ingress resource. In such cases, the Ingress controller needs to have a default behaviour to handle these unmatched requests.
- The Ingress Default Backend provides this default behaviour. It is a special service or endpoint that is configured as the default backend for the Ingress controller. When an incoming request does not match any defined rules, it is automatically routed to this default backend.
- The purpose of the default backend is to handle these unmatched requests gracefully. Typically, it returns a user-friendly error page or redirects the request to a specific service or URL. The specific behaviour of the default backend can be customized based on the needs of the application.
32. How to run a POD on a particular node?
- To operate a POD on a particular node in Kubernetes, you can use node affinity rules. Node affinity permits you to specify restrictions on which nodes your pods can be scheduled.
- Here’s how you can run a POD on a specific node:
- Identify the title or label of the node you want to run the POD on. You can use the kubectl get nodes order to list all the nodes in your cluster and find the one you want.
- Add a node selector to your POD’s YAML file. In the spec section of your POD description, add the nodeSelector field with the key-value pair that corresponds to the label of your preferred node.
- Apply the modifications by running the kubectl apply -f <pod-file>.yaml command, replacing <pod-file> with the path to your altered POD YAML file.
- Once applied, Kubernetes will schedule your POD only on nodes that match the identified node selector.
33. What is Minikube?
Minikube is an open-source tool that permits developers to run a single-node Kubernetes cluster on their local machine. It is created to make it easy to develop and experiment with Kubernetes applications locally without requiring access to a full-scale Kubernetes cluster. Minikube delivers a lightweight, standalone version of Kubernetes that can be utilized for testing and experimentation. With Minikube, developers can quickly spin up a local Kubernetes environment, deploy their applications, and test them in a real-world environment. Overall, Minikube is a powerful tool for developers who want to streamline or simplify their Kubernetes workflow and enhance their overall productivity.
34. What is the difference between a replica set and a replication controller?
- A replica set and a replication controller are both elements of Kubernetes, a famous container orchestration platform. While they serve similar objectives, there are some key differences between them.
- A replica set is responsible for ensuring that a defined number of identical pods are running at all times. It is a higher-level conception that provides declarative control over pod replication. Replica sets use labels or tags and selectors to identify the pods they operate. If a pod fails or is deleted, the replica set automatically creates a new one to maintain the desired number of replicas. Replica sets are typically used for scaling applications horizontally, allowing multiple instances of the same pod to manage increased traffic or workload.
- On the other hand, a replication controller is an older version of the replica set. It was introduced in earlier versions of Kubernetes and has since been replaced by the replica set. However, replication regulators are still supported for backward compatibility reasons. Like replica sets, replication controllers also confirm that a specific number of pods are running, but they lack some of the advanced components and flexibility provided by replica sets. Replication controllers use selectors to identify the pods they handle and perform basic scaling operations.
- One significant difference between replica sets and replication controllers lies in their selector capabilities. Replica sets support set-based selectors, which allow for more complex matching criteria, such as matching pods based on numerous labels or label expressions. Replication controllers, on the other hand, only support equality-based selectors, limiting their matching capabilities.
- Another distinction is that replica sets support rolling updates out of the box. Rolling updates allow you to revise your application by gradually replacing old pods with refreshed ones, minimizing downtime. Replication controllers do not provide built-in support for rolling updates, requiring manual intervention to accomplish the same functionality.
35. What are the ways to provide API Security on Kubernetes?
Below mentioned are some of the best ways to provide API Security on Kubernetes:-
- Authentication and Authorization: Implementing authentication mechanisms such as OAuth, JWT (JSON Web Tokens), or OpenID Connect can help secure access to your APIs. It ensures that only approved users or services can interact with the identity of clients accessing the API server.
- Transport Layer Security (TLS): Allow TLS encryption for all API communications to assure data confidentiality and integrity. It can be done by configuring Kubernetes Ingress controllers or using a service mesh like Istio.
- API Gateways: Implement an API gateway to act in place so you can enforce fine-grained access controls using Kubernetes RBAC (Role-Based Access Control). RBAC allows you to determine roles and permissions for different users or groups, limiting what activities they can perform within the cluster.
- Transport Layer Security (TLS): Encrypting the contact between clients and the Kubernetes API server using TLS certificates is crucial for securing sensitive data. This ensures that data role-Based Access Control) defines and enforces access policies for distinct users or groups. RBAC allows fine-grained command over who can perform specific actions within the cluster.
- Transport Layer Security (TLS): Enable TLS encryption for communication between clients and the API server. It ensures that data transmitted over the network is secured from eavesdropping and tampering.
- Network Policies: Use network policies to control traffic discharge within the cluster. By defining rules at the network level, you can bind communication between different pods or namespaces, adding an extra layer of security.
- Pod Security Policies: Implement security policies at the pod level to manage what actions containers running within pods can perform. Pod Security Policies permit you to define restrictions on privilege escalation, host access, and other security-sensitive aspects.
- Container Image Security: Ensure that container images used in your Kubernetes cluster are free from susceptibilities by regularly scanning them for known security issues. Utilize trusted image registries and implement image signing to control unauthorized modifications.
- Logging and Monitoring: Implement robust logging and monitoring solutions to identify and respond to security incidents promptly transmitted over the network that cannot be intercepted or tampered with.
- Container Security: Ensuring the containers running within your Kubernetes cluster are safe for API security. Regularly scanning container pictures for vulnerabilities, using photo signing and verification, and implementing runtime security actions like pod security policies can help protect against malicious code implementation.
36. Give examples of some recommended security measures for Kubernetes.
Given below are the examples of some recommended security measures for Kubernetes:-
- Providing restricted access to etcd
- Regular security updates
- Defining resource quotas
- Auditing support
- Strict resource policies
- Network segmentation
- Regular scans for security vulnerabilities
- Using images from repositories that are authorized
37. Explain the list of objects of Kubernetes.
The list of objects of Kubernetes is as follows:-
- Replication sets and controllers
- Distinctive identities
- Daemon sets
- Stateful sets
- Jobs and cron jobs
38. What are Stateful sets in Kubernetes?
- StatefulSets in Kubernetes are a type of workload that helps you to manage stateful applications. Unlike traditional deployments in Kubernetes, StatefulSets provide assurances about the ordering and uniqueness of pods. It means you can deploy applications that require stable network identities, persistent storage, and ordered deployment and scaling.
- StatefulSets are useful for operating applications such as databases, key-value stores, and other stateful applications which require stable or regular network identities and persistent storage. They ensure that each pod in the StatefulSet has a unique and stable hostname, which is based on the name of the StatefulSet and the ordinal index of the pod. It makes it easier to connect to and manage individual pods within the StatefulSet.
- StatefulSets also helps to provide support for persistent storage, allowing you to connect a volume to each pod in the StatefulSet.
- It ensures that data is preserved even if a pod is renewed or moved to a different node. The continuous volume claims associated with each pod are also automatically deleted when the pod is deleted.
- In complement to these features, StatefulSets provide assurances about ordering pod creation and deletion. It means that when scaling up or down a StatefulSet, pods are created or deleted in a predictable order. Therefore, it is particularly important for applications that require strict ordering during deployment or scaling.
39. What are the various container resource monitoring tools?
The following are the various container resource monitoring tools:-
40. What are Daemon sets?
DaemonSets are a variety of workloads in Kubernetes that provide a pod running on every node in a cluster. Unlike other workload kinds, such as Deployments or ReplicaSets, which ensure a certain number of replicas are running across the cluster, DaemonSets guarantee that a specific pod is present on each node.
DaemonSets are useful for operating background services or infrastructure components that need to be present on every node. They are often used for tasks like log collection, monitoring agents, or network proxies. By operating these services as DaemonSets, you can ensure they are always available and distributed across the entire cluster.
When a new node is added to the cluster, a pod managed by a DaemonSet is automatically scheduled onto that node. Similarly, if a node is removed from the cluster, the corresponding pod will be terminated. It makes DaemonSets highly resilient and adjustable to changes in the cluster’s size or composition.
41. Explain the uses of Daemon sets.
The explanation of the uses of Daemon sets are as follows:-
- Logging and Monitoring: Daemon sets can be used to deploy log collectors and monitoring agents on each node. It ensures that logs and metrics from every node are gathered and monitored centrally.
- Networking: Daemon sets are used to deploy network plugins or load balancers on each node. It allows for efficient communication and load balancing between pods running on different nodes.
- Security: Daemon sets are also used to deploy security agents or tools that monitor and implement security policies on each node. It helps in detecting and mitigating security dangers across the cluster.
- Resource Management: Daemon sets are used to deploy resource management agents that monitor and control resource usage on each node. It ensures optimal utilization of resources and prevents resource contention.
- Custom Applications: Daemon sets can also be used to deploy custom applications that help to run on every node, such as distributed databases or distributed file systems.
Therefore, Daemon sets provide a suitable way to deploy and manage system-level daemons or agents across a Kubernetes cluster, ensuring the availability and functionality of critical services or applications.
42. What are the uses of the Google Kubernetes Engine (GKE)?
Given below is a detailed explanation of the uses of the Google Kubernetes Engine (GKE):-
- Application Deployment: GKE streamlines the process of deploying applications in containers. It provides a platform for operating and managing containerized workloads, making it easier to deploy applications consistently across distinct environments.
- Scalability: GKE allows easy scaling of applications by automatically managing the underlying infrastructure. It allows users to add or remove resources based on need, ensuring that applications can manage increased traffic or workload.
- High Availability: GKE ensures high availability of applications by automatically distributing workloads across numerous nodes in a cluster. It monitors the health of applications and automatically resumes failed containers, minimizing downtime.
- Load Balancing: GKE incorporates Google Cloud Load Balancing to distribute incoming traffic across considerable instances of an application. It helps optimize performance and ensures that applications can manage high-traffic loads.
- Automatic Updates and Patches: GKE handles the underlying Kubernetes infrastructure, including updates and patches. It assures that the cluster is up-to-date with the latest security patches and Kubernetes versions, lowering the operational overhead for users.
- Monitoring and Logging: GKE provides built-in monitoring and logging capabilities, letting users gain insights into their application’s performance and troubleshoot problems more effectively. It integrates with other Google Cloud services like Stackdriver for comprehensive monitoring and logging.
- Security: GKE combines various security features to protect containerized applications. It provides safe access controls, network policies, and encryption at rest for data stored in containers.
- Cost Optimization: GKE offers cost optimization features such as autoscaling and node auto-provisioning. These features help optimize resource utilization and lower costs by automatically modifying the number of nodes based on workload demands.
43. Explain the objectives of the replication controller.
The replication controller has several objectives:
- Ensuring Availability: The replication controller ensures that a defined number of pod replicas are always running and available. It scrutinizes the status of pods and automatically replaces any forgotten or terminated pods with new ones.
- Scaling Applications: The replication controller permits you to scale your application horizontally by raising or lowering the number of pod replicas. It helps in managing increased traffic or distributing the workload across numerous pods.
- Rolling Updates: The replication controller facilitates rolling updates by gradually replacing old pods with renewed ones. It ensures that your application remains available during the update process, without any downtime.
- Load Balancing: By maintaining a defined number of pod replicas, the replication controller assists in distributing incoming traffic evenly across all the pods. It helps to improve the all-around performance and reliability of your application.
- Self-Healing: In case a pod fails or becomes unresponsive, the replication controller automatically creates new replicas to replace them. This self-healing mechanism ensures that your application stays operational even in the presence of failures.
44. What are the Secrets of Kubernetes?
The objects that store or contain sensitive or confidential information such as passwords, and username after performing encryptions is known as Secrets in Kubernetes.
45. What is PVC in Kubernetes?
The full form of PVC is a Persistent Volume Claim. PVC is a storage requested by Kubernetes for pods. The user does not need to know the underlying provisioning. The claim should be created in the same namespace where the pod is created.
46. What are the disadvantages of Kubernetes?
The disadvantages of Kubernetes are as follows:-
- Complexity: Kubernetes is a complicated system with a steep learning curve. It needs an in-depth understanding of containerization, networking, and distributed systems. Setting up and handling a Kubernetes cluster can be challenging for beginners.
- Resource Intensive: Kubernetes requires a significant amount of resources to run efficiently. It requires a cluster of machines to perform, which can be expensive in terms of hardware and infrastructure necessities.
- Operational Overhead: Managing a Kubernetes cluster involves continuous monitoring, troubleshooting, and maintenance tasks. It can add to the functional overhead and require trustworthy resources and expertise.
- Lack of Native Support: While Kubernetes has the standard for container orchestration, some tools and platforms may not have native support for Kubernetes. It can lead to compatibility problems and require supplementary workarounds or customizations.
- Steep Learning Curve: As cited earlier, Kubernetes has a steep learning curve. It needs developers and operators to invest time and effort in comprehending its concepts, architecture, and best practices.
- Limited Windows Support: Kubernetes was initially designed for Linux-based systems, and although there is ongoing development for Windows support, it is still relatively delimited compared to Linux.
47. What is a sidecar container, and what is its role?
A sidecar container is a secondary container that drives alongside the main container within a single pod in a Kubernetes cluster. Its function is to provide additional functionality or support to the main container, without instantly interfering with its operation.
The main objective of a sidecar container is to improve the capabilities of the main container by offloading certain tasks or responsibilities. It can manage tasks such as logging, monitoring, security, networking, or any other auxiliary function that is needed to support the main container’s procedure.
Separating these additional functionalities into different sidecar containers allows for better modularity and scalability within the application architecture. Each sidecar container can be independently developed, updated, and scaled as needed without affecting the main container.
Sidecar containers communicate with the main container and other sidecar containers via local inter-process communication mechanisms like shared volumes or network interfaces. They can share resources, such as file systems or environment variables with the main container.
The use of sidecar containers facilitates the principle of single responsibility and allows for better separation of concerns in a microservices architecture. It streamlines the deployment and management of complicated applications by encapsulating different functionalities into separate containers within a single pod.
48. Which are the most important commands of Kubectl?
The most important commands of Kubectl are as follows:-
- kubectl attach
- kubectl apply
- kubectl config
- kubectl config current-context
- kubectl config set etc.
- kubectl annotate
- kubectl cluster-info
- kubectl autoscale
49. What is Sematext Docker Agent?
Sematext Docker Agent is a weightless and efficient monitoring agent specially developed to collect and ship Docker container metrics, logs, and events. It provides a real-time understanding of the performance and health of your Dockerized applications and infrastructure.
Sematext Docker Agent can be easily deployed as a container alongside your other Docker containers or as a standalone agent on your host machine. It supports diverse monitoring features such as container resource usage, network activity, disk I/O, and container logs. With the help of Sematext Docker Agent, you can gain incalculable visibility into your Docker environment and ensure optimal performance and reliability.
50. What are the different types of Kubernetes Volumes?
Following is the list of the different types of Kubernetes Volumes:-
- GCE persistent disk