Container-based microservices architectures have fundamentally changed how development and operations teams test, deploy, and maintain modern software. Modernizing companies is easier with containers. However, containers also introduce new challenges and complexity through the creation of new infrastructure.
Kubernetes, originally developed by Google, is an open-source container orchestration system that automates the deployment, scaling, and management of containerized apps. In fact, Kubernetes has established itself as the defacto standard for container orchestration and is the flagship project of the Cloud Native Computing Foundation (CNCF), backed by key players like Google, AWS, Microsoft, IBM, Intel, Cisco, and Red Hat. Check out this CNCF certified Kubernetes Certification.
Kubernetes allows you to easily deploy and manage applications in microservice architectures. Kubernetes creates an abstraction layer over a group hosts so that developers can deploy their applications. Kubernetes then manages the following activities:
- Resource consumption can be controlled by an application or a team
- Spreading application load evenly across the host infrastructure
- Automated load balancing requests for different instances of an app
- Monitor resource consumption and limit to stop applications from using too much resource and allow applications to be restarted again
- If there are insufficient resources on a host or the host is dead, you can move an application instance to another host.
- Automatically leveraging additional resources when a new host joins the cluster
- Easily performing canary deployments and rollbacks
Okay, but what’s the fuss about Kubernetes? Why are Kubernetes so beloved?
As organizations shift to container-based microservices and cloud native architectures, they are looking for proven platforms. There are four reasons why Kubernetes is popular with practitioners:
1. Kubernetes makes it easier to move faster. Indeed, Kubernetes allows you to deliver a self-service platform-as-a-service (PaaS) that creates a hardware abstraction layer for development teams. Your development teams will be able to quickly and efficiently request the resources that they require. They can request additional resources as needed to handle more load. This is possible because all resources are part of an infrastructure that is shared by all teams.
You don’t need to fill out lengthy forms to request machines that will run your application. You can just provision your application and use the Kubernetes tooling to automate packaging, deployment and testing. (We’ll talk more about Helm in an upcoming section.)
2. Kubernetes can be cost-effective.Containers and Kubernetes allow for better resource utilization than hypervisors or VMs. Containers are lightweight and require less memory and CPU resources to run.
3. Kubernetes can be cloud-agnostic. Kubernetes runs onAmazon Web Services (AWS?Microsoft AzureThe, andGoogle Cloud Platform (GCPYou can also use it on your premises. You can move workloads without having to redesign your applications or completely rethink your infrastructure–which lets you standardize on a platform and avoid vendor lock-in.
Companies like Rancher, Cloud Foundry and Kublr offer tools to help you manage and deploy your Kubernetes cluster either on-premises or on any cloud provider.
4. Kubernetes will be managed by cloud providers.Kubernetes, as we have already stated, is the current standard for container orchestration tools. It should come as no surprise that major cloud providers are offering plenty of Kubernetes-as-a-service-offerings.Amazon EKS?Google Cloud Kubernetes Engine?Azure Kubernetes Service (AKS)?Red Hat OpenShiftAndIBM Cloud Kubernetes ServiceAll offer full Kubernetes platform administration so that you can concentrate on what is most important to you: shipping applications that delight your customers.
How does Kubernetes function?
Kubernetes’ central component is thecluster. A cluster is a collection of virtual or physical machines that serve a specific function as either a master or a node. Each node hosts a group of containers that contain your applications. The master communicates with the nodes when containers should be created or destroyed. It also tells nodes how traffic can be rerouted based on new container alignments.
Kubernetes master (or control plane) is where administrators and other users can interact with the cluster in order to manage the deployment and scheduling of containers. A cluster will always have at minimum one master, depending on its replication pattern.
The master holds the configuration and state data for the whole cluster.etceA distributed, persistent key-value storage. Every node has access ectd. This allows them to learn how to maintain their containers’ configurations. You can either run etcd in standalone or Kubernetes master configurations.
Through the, masters communicate with other members of the cluster.kube-apiserverThe main access point to control plane. The kube-apiserver, for example, ensures that configurations in etcd match configurations of containers in the cluster.
TheKube-controllerManagerControl loops are used to manage the state and status of the cluster using the Kubernetes server. This service handles all aspects of control, including deployments, replicas, as well as nodes. The node controller, for example, is responsible to register a node and monitor its health throughout its lifetime.
The cluster manager tracks and manages node workloads.kube-scheduler. This service monitors the resources and capacity of nodes and assigns work based on their availability.
Thecloud-controller-managerKubernetes service that keeps it cloud-agnostic. The cloud-controller-manager serves as an abstraction layer between the APIs and tools of a cloud provider (for example, storage volumes or load balancers) and their representational counterparts in Kubernetes.
All nodes in a Kubernetes cluster must be configured with a container runtime, which is usually Docker. Container runtime manages Kubernetes containers and deploys them to cluster nodes. Your applications (web servers, databases, API servers, etc.) The containers are used to store your applications (web servers, databases, API servers, etc.).
Every Kubernetes Node runs an agent process known as aKubeletThis is responsible for controlling the state of the node. It starts, stops, and maintains application containers according to instructions from the control plane. The kubelet gathers performance and health information about the node, pods and containers it runs. The control plane shares this information to aid in scheduling decisions.
TheKube-proxyIt is a network proxy which runs on cluster nodes. It can also be used to balance load for services that are running on a single node.
The basic scheduling unit for a computer is apod?This cluster consists of one to several containers that can be shared resources and are guaranteed to be colocated on the same host machine. Each pod has its own IP address, which allows the application to use port without conflict.
You can describe the desired state of a pod’s containers using a YAML object or JSON object called aPod Spec.These objects are sent to the API server and then passed to the Kubelet.
One or more pods can be used to define one or both.VolumesYou can expose any disks, either local or network, to the pod and allow different containers to share storage space. Volumes can be used to store content that is downloaded by one container and then uploaded by another. Kubernetes provides a load balancer called a service to make it easier to send requests to multiple pods. AServiceA logical set of pods is selected based uponLabels(explained further below). Services can only be accessed from within the cluster by default. However, you can allow public access to these services if you wish to receive requests from outside of the cluster.
Replicas and deployments
Installation is a YAML object which defines the pods as well as the number of containers, calledreplicasFor each pod, With aReplicaSetThe deployment object also includes the part containing the. The replica set makes sure that another pod can be scheduled on an available node in the event of a pod being lost or disabled.
DaemonSet: A daemon is a program that deploys and runs a particular daemon (in an instance called a pod) on the nodes specified. DaemonSets can be used to provide maintenance or services to pods. DaemonSets are used to provide services or maintenance for pods.
Namespaces enable you to create virtual clusters over a physical one. Namespaces can be used in environments that have many users spread across multiple projects or teams. They can be used to assign resource quotas or logically isolate cluster resources.
LLabelsThese key/value pairs can be assigned to pods or other objects in Kubernetes. Kubernetes operators can use labels to group and select subsets of objects. Labels allow you to quickly drill down to the information that you are most interested in when you monitor Kubernetes objects.
Persistent storage volumes and stateful sets
StatefulSetsYou can assign pods unique IDs for moving pods between nodes or maintaining networking between pods. Similar functionality is available persistent storage volumes. Provide storage resources to a cluster, which pods can access when they are deployed.
Other useful components
These Kubernetes components can be useful, but are not necessary for Kubernetes regular functionality.
Kubernetes provides this mechanism for DNS-based service discovery between pods. This DNS server can be used in conjunction with any other DNS servers in your infrastructure.
If you have a logging tool, you can integrate it with Kubernetes to extract and store application and system logs from within a cluster, written to standard output and standard error. Kubernetes doesn’t support cluster-level logs. You will need to provide your own log storage.
Helm: Managing Kubernetes Applications
Helm is an application package management registry for Kubernetes, maintained by the CNCF. You can download Helm charts to pre-configured software resources that you can use in your Kubernetes environment. According to a 2020 CNCF survey, 63% of respondents said Helm was the preferred package management tool for Kubernetes applications. DevOps teams can quickly get up to speed with Kubernetes application management using Helm charts. They can use existing charts they have created, which they can then share, modify, and deploy to their production and development environments.
Kubernetes and Istio are a very popular pair
A microservices architecture such as those used in Kubernetes allows for a variety of services. You can also configure how service instances will perform crucial actions like load balancing, service discovery, authentication, authorization, and data encryption. Istio is an example of such a service mesh. Current thinking by tech leaders like Google and IBM suggests that they are.It is becoming increasingly difficult to separate the two.
Istio is used by the IBM Cloud team to address security, visibility and control issues that it encountered when deploying Kubernetes on a large scale. Istio is a tool that IBM uses to help it:
- Control traffic flow by connecting services
- Secure interactions between microservices using flexible authorization and authentication policies
- Assist IBM in managing services in production by providing a control point
- Observe what’s happening in their services, via an adapter that sends Istio data to New Relic–allowing it to monitor microservice performance data from Kubernetes alongside the application data it’s already gathering
Kubernetes Adoption Challenges
Kubernetes has clearly come a long ways in its first five years. This kind of rapid growth comes with occasional growing pains. These are some of the challenges associated with Kubernetes adoption.
1.It can be difficult to understand the Kubernetes technology landscape.Developers love Kubernetes’ ability to innovate quickly. Sometimes too much innovation can lead to confusion, especially when Kubernetes’ central code base is moving at a faster pace than the users. It can be difficult for new users to understand the complex landscape when there are so many managed service providers and platforms.
2.The business priorities of forward-looking IT and dev teams are not always met by their IT teams.Budgets that are only used to maintain the status quo can make it difficult for teams to obtain funding to support Kubernetes adoption efforts. Such experiments take up a lot of team time and resources. Enterprise IT teams can be slow to adapt and are often vulnerable to risk.
3.Teams are still learning the skills needed to leverage Kubernetes.Not until a few decades ago, developers and IT personnel had to adjust their practices in order to adopt containers. Now, they must also adopt container orchestration. Enterprises that want to adopt Kubernetes must hire developers who are proficient in coding and can manage operations. They also need to understand data workflows, storage and application architecture.
4.Kubernetes are difficult to manage.You can actually read any number Kubernetes horror stories, from DNS outages to “a cascading fail of distributed systems”- all in the Kubernetes Failure Stories GitHub repo.