SERVICIOS y LOAD BALANCERS en KUBERNETES

Pelado Nerd

7 Jan 201909:47

Summary

TLDRThe video script discusses the process of setting up a cluster and deploying posts using Kubernetes. It explains different types of services, including NodePort, ClusterIP, and LoadBalancer, and how they are used to access applications within a cluster. The script also covers the dynamic nature of pods, the creation of a WordPress service, and the use of external IPs for accessing services. It highlights the importance of load balancers for maintaining a consistent IP address and ensuring high availability, even when pods are destroyed and recreated.

Takeaways

😀 The script discusses learning to set up one's own cluster and deploying posts.
💡 It introduces the concept of services within a cluster and their different types.
🔧 The script explains how to create load balancers automatically using cloud services.
📈 It highlights the dynamic nature of pods, which can be recreated with new IPs if they die.
🌐 Discusses the use of services to route traffic to pods based on labels or tags.
🚀 Demonstrates how to create a service with a fixed IP within the cluster for internal access.
🌐 Explains the use of NodePort services to expose applications on a specific port on each node's public IP.
🔄 Covers the creation of LoadBalancer services that integrate with cloud providers to manage external access.
🛠️ The script touches on the automation of service creation and how it simplifies the management of dynamic infrastructure.
📝 It concludes by emphasizing the ease of managing services with Kubernetes, including the ability to create and delete them without manual intervention.

Q & A

What is the purpose of creating a cluster in the context of the video script?
-The purpose of creating a cluster is to support the deployment of applications and services, ensuring they can scale and be managed more efficiently.
What does the term 'service' refer to in the script, and why is it important?
-In the script, a 'service' refers to a Kubernetes resource that defines a logical set of pods and a policy by which to access them. It's important because it enables communication between different parts of an application and provides a way to access them consistently, regardless of the underlying pods' lifecycle.
What is the issue with using NodePort for accessing services in a cluster?
-The issue with NodePort is that it requires pointing to the public IP of each worker node to reach a specific port, which is not ideal for maintaining a stable access point as pods can be rescheduled or recreated on different nodes.
How does a ClusterIP service differ from a NodePort service?
-A ClusterIP service is accessible only within the cluster, providing a stable IP address that remains the same regardless of the pods it targets, whereas a NodePort service is accessible from outside the cluster by directing traffic to a specific port on each worker node.
What is the role of a LoadBalancer service in Kubernetes?
-A LoadBalancer service in Kubernetes connects to the cloud provider's API and creates an external load balancer that distributes traffic across all worker nodes, providing a stable external IP for accessing the application.
Why might a service be unable to access a backend if the backend's IP changes?
-If the backend's IP changes, any service that is not configured to handle dynamic IP assignments will be unable to access it, as it will still be trying to connect to the old IP address.
What happens when a pod is destroyed in Kubernetes?
-When a pod is destroyed, it is removed from the cluster, and its IP address is no longer available. If a service was pointing to that pod, it would need to be updated to point to a new pod with a new IP address.
How can a service ensure it always points to the correct backend, even if the backend's IP changes?
-A service can ensure it always points to the correct backend by using a selector that targets the appropriate labels on pods, allowing it to redirect traffic to any pod that matches those labels, regardless of IP changes.
What is the significance of using a DNS name to access a service in Kubernetes?
-Using a DNS name to access a service allows for a more flexible and stable access point, as the DNS resolver will automatically direct traffic to the correct service IP, even if the underlying pods or their IPs change.
How can one view the list of services in a Kubernetes cluster?
-One can view the list of services in a Kubernetes cluster by using the command `kubectl get services`, which will display the services along with their types and cluster IPs.
What does the script suggest about managing services and pods in Kubernetes?
-The script suggests that Kubernetes manages services and pods dynamically, allowing for the creation, destruction, and rescheduling of pods without affecting the stability of the services that rely on them.

Outlines

00:00

🤖 Deploying and Managing Cluster Services

This paragraph discusses the process of deploying a self-hosted cluster and the intricacies of managing services within it. The speaker explains the initial learning curve and cost involved in setting up a cluster, and then delves into the concept of services, their types, and how to create and manage them. The explanation includes the use of 'NodePorts' for internal access, the dynamic nature of pods, and the creation of a service to provide stable access to applications within the cluster. The paragraph also touches on the challenges of using public IPs for external access and introduces the idea of using 'LoadBalancer' services for cloud provider-managed load balancing.

05:00

🌐 Advanced Service Configurations and Load Balancing

The second paragraph focuses on advanced configurations for services within a cluster, particularly on the use of 'LoadBalancer' services. It explains how to create a 'LoadBalancer' service that connects to the cloud provider's API to manage external traffic. The speaker provides a step-by-step guide on verifying the creation of the load balancer through the web interface and emphasizes the importance of persistent IP addresses for stable access to services. The paragraph also covers the automatic handling of service creation and destruction, ensuring that the load balancer always directs traffic to the correct nodes, even when pods are destroyed and recreated. Additionally, it mentions the possibility of adding further configurations such as certificates and health check rules to enhance service security and reliability.

Mindmap

Keywords

💡Cluster

A cluster in the context of the video refers to a group of computers working together closely so that they can be viewed as a single system. It is central to the video's theme as it discusses setting up and deploying applications within a cluster environment. For example, the script mentions 'levantar nuestro propio clúster' which translates to 'lifting our own cluster', indicating the process of setting up a cluster.

💡Service

In the script, a 'service' is a Kubernetes resource that defines a logical set of pods and a policy by which to access them. It is a fundamental concept in the video, as it discusses different types of services and how they can be used to maintain access to applications even if the underlying pods change. The term is used when explaining 'no port' services, which create a specific port that points to the service on each pod.

💡Pod

A pod is the smallest deployable unit in Kubernetes and can be thought of as a wrapper around a container. The video discusses the dynamic nature of pods, which can be created, destroyed, and recreated as needed. This is illustrated when the script mentions that if a pod 'muere' (dies), it does not 'resucitan' (resurrect), but a new one can be created.

💡Deployment

A deployment in Kubernetes is a way to declare the desired state of a set of pods. The video touches on the deployment of applications within a cluster, emphasizing the need for a deployment controller to manage the pods. The script refers to 'desplegar los posts', which means deploying the pods, as part of setting up the cluster.

💡Load Balancer

A load balancer is a service that distributes network or application traffic across multiple servers. The video explains how to create a load balancer service in Kubernetes, which connects to the cloud provider's load balancer to manage traffic to the pods. The script mentions 'load balance' as a type of service that can be created, which is crucial for maintaining access to applications as pods are dynamically managed.

💡IP Address

An IP address is a unique identifier for devices on a network. The video discusses the importance of IP addresses in accessing services within a cluster, both internally and externally. The script mentions 'IP pública' (public IP) and 'IP interna de la red de los bots' (internal IP of the bot network), highlighting the use of IP addresses for service access.

💡DNS

DNS, or Domain Name System, is the system that translates human-friendly domain names into IP addresses. The video mentions DNS in the context of resolving service names to their corresponding IP addresses within a cluster. The script refers to 'dns de gobernantes', indicating the use of DNS for service discovery.

💡Kubernetes

Kubernetes is an open-source platform for managing containerized workloads and services. The video's theme revolves around using Kubernetes to create and manage clusters, services, and deployments. The script uses terms like 'kubectl', which is a command-line tool for interacting with Kubernetes clusters, indicating the use of Kubernetes throughout the video.

💡Controller

In Kubernetes, a controller is a control loop that watches the state of the cluster and makes changes to move the current state towards the desired state. The video discusses the role of controllers in managing the lifecycle of pods and services. The script mentions 'replaciendo el controller', which refers to the process of a controller managing the replacement of pods.

💡Cloud Provider

A cloud provider is a company that offers cloud services, such as computing power, storage, and databases. The video mentions connecting to a cloud provider's API to create load balancers, indicating the integration of Kubernetes with cloud services. The script refers to 'proveedor de nube', which is essential for setting up external access to services within the cluster.

💡Persistence

Persistence in the context of the video refers to the ability of a service to maintain its state or IP address even when the underlying pods are destroyed and recreated. The video discusses the importance of persistence for services, especially when using load balancers. The script mentions that services should maintain the 'misma ip', emphasizing the need for persistent access points.

Highlights

Learning to create your own cluster at a cost of 100 dollars.

Understanding how to support initial posts with an application to control and create a small service.

Explanation of what services are and the different types of services.

Creating balances automatically using Digital Ocean.

Introduction to Kubernetes services and how they work.

The downside of using NodePort services as they require pointing to the public IP from each worker.

How pods are dynamic and can be recreated with new IPs.

Using services to direct traffic based on labels for consistent access.

The creation of a service for WordPress with an internal cluster IP for internal access.

Exploring the use of external IPs and NodePorts for external access to services.

The importance of not relying on the public IP of a node for consistent service access.

Introduction to LoadBalancer services that integrate with cloud providers for external access.

How LoadBalancer services maintain a constant IP while workers can be recycled.

The process of creating a LoadBalancer service and its automatic setup with cloud provider APIs.

Demonstration of destroying and recreating nodes without affecting the LoadBalancer's constant IP.

The ability to add custom settings like certificates and health checks to services.

Automatic management of services including creation and deletion without manual intervention.

The option to create and delete LoadBalancer services and their impact on the application's accessibility.