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Kubernetes Orchestration

Kubernetes, often abbreviated as K8s, is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.

Kubernetes is designed for distributed systems where large numbers of containers must coordinate reliably and scale efficiently. It automates critical operational capabilities such as scheduling, load balancing, scaling, and failure recovery, reducing the operational complexity of managing containerized workloads across clusters.

By abstracting infrastructure concerns, Kubernetes enables development and DevOps teams to focus on application delivery rather than cluster operations. It is a foundational technology for cloud-native applications and microservices-based architectures.

Kubernetes Architecture​

Kubernetes follows a control plane and worker node architecture to manage and orchestrate containers across a cluster.

Control Plane​

The control plane manages the overall state of the Kubernetes cluster. It makes scheduling and deployment decisions, tracks cluster health, and ensures that the actual state of the system matches the desired state. Key control plane components include:

  • kube-apiserver: The front end of the control plane that exposes the Kubernetes API. It validates and processes REST requests and coordinates communication between cluster components.
  • kube-scheduler: Assigns newly created pods to nodes based on resource availability, constraints, and scheduling policies.
  • kube-controller-manager: Runs control loops that continuously monitor the cluster state and take corrective actions. For example, if a pod fails, the controller manager ensures a replacement is created.
  • etcd: A distributed key-value store that persists all cluster data, including configuration, state, and metadata. It serves as the authoritative source of truth for the cluster.

Nodes​

Nodes are the machines that run containerized workloads. Each node includes the components required to run and manage containers:

  • kubelet: An agent that runs on each node and ensures that containers are running as defined. It communicates with the API server and performs health checks.
  • kube-proxy: Manages network routing and load balancing for services, ensuring traffic is forwarded to the correct pods.
  • Container runtime: The software responsible for running containers. Common runtimes include containerd and CRI-O. Docker is also commonly used as a container runtime in many environments.

Core Kubernetes Concepts​

  • Containers: Containers are lightweight, portable, and self-contained execution units that package an application together with its dependencies. Kubernetes is designed to manage containers at scale across distributed systems.
  • Pods: A pod is the smallest deployable unit in Kubernetes. It consists of one or more containers that share networking and storage resources. Pods are ephemeral and may be created, destroyed, or replaced automatically during scaling or application updates.
  • Nodes: A node is a physical or virtual machine that runs pods. Kubernetes schedules workloads onto nodes. A cluster consists of control plane nodes that manage the system and worker nodes that run application workloads.
  • Clusters: A cluster is a collection of nodes managed by Kubernetes. It includes the control plane and worker nodes, and it provides the execution environment for containerized applications.
  • ReplicaSets: A ReplicaSet ensures that a specified number of identical pod replicas are running at any given time. It automatically adjusts the number of pods to match the desired state and is commonly used to support scaling and resilience.
  • Deployments: A Deployment is a higher-level abstraction that manages ReplicaSets. It enables rolling updates and rollbacks, allowing applications to be updated without downtime by gradually replacing existing pods with new versions.
  • Services: A Service defines a stable access point for a set of pods. Because pods are dynamic and may change over time, Services provide a consistent DNS name or IP address for accessing applications. Common service types include:
    • ClusterIP: Exposes the service within the cluster.
    • NodePort: Exposes the service to the outside world through a static port on each node.
    • LoadBalancer: Exposes the service via a load balancer (e.g., on cloud providers).
    • ExternalName: Maps the service to an external DNS name.
  • Namespaces: Namespaces partition a cluster into logical environments. They are commonly used to separate teams, applications, or environments such as development, staging, and production, improving resource organization and access control.
  • ConfigMaps: ConfigMaps store non-sensitive configuration data as key-value pairs. Applications can consume these values as environment variables or configuration files.
  • Secrets: Secrets store sensitive information such as credentials, tokens, and certificates. They are encoded and securely injected into pods at runtime.
  • Persistent Storage: Kubernetes manages persistent data using Persistent Volumes (PVs) and Persistent Volume Claims (PVCs). Persistent Volumes are provisioned storage resources, while Persistent Volume Claims represent requests for storage by applications. This model ensures data durability across pod restarts and rescheduling.

Benefits of Kubernetes​

  • Automated Container Orchestration: Automates deployment, scaling, and lifecycle management of containers.
  • High Availability: Detects failures and automatically recovers workloads to maintain application uptime.
  • Portability: Supports consistent application deployment across on-premises, private cloud, and public cloud environments.
  • Scalability: Scales applications horizontally based on demand, enabling efficient handling of traffic fluctuations.
  • Self-Healing: Continuously monitors workload health and replaces or restarts failed components automatically.
  • Resource Efficiency: Optimizes resource usage through intelligent scheduling, resource requests, and limits.

Kubernetes Integration in BuildNinja​

BuildNinja integrates with Kubernetes in two primary ways: as a deployment target for containerized applications produced by CI, and as a hosting platform for the BuildNinja Server and Agent.

Kubernetes Deployment Support​

BuildNinja can deploy containerized applications to Kubernetes clusters as part of CI/CD. Build steps executed through the Command Line Runner can invoke kubectl commands such as kubectl apply or kubectl set image to update workloads in a target cluster.

This model requires kubectl to be installed and configured on the BuildNinja Agent, with access to a valid kubeconfig. Sensitive values, such as cluster credentials or configuration paths, are stored securely as Build Parameters and injected at runtime.

This workflow is explained in detail in the How to Deploy a Containerized Application to KubernetesConfigure a deployment build configuration in BuildNinja to deploy a pre-built Docker image into a Kubernetes cluster as part of the Continuous Deployment (CD) process. guide.

Containerized BuildNinja Architecture​

BuildNinja Server and Agent can be deployed on Kubernetes, enabling teams to run the BuildNinja platform within their existing cluster infrastructure. Kubernetes manages availability, restarts, and scaling of BuildNinja components.

Detailed instructions are available in the Configure Server and Agent with Docker and KubernetesKubernetes provides a scalable and automated way to deploy, manage, and orchestrate BuildNinja Server and Agent across multiple environments. guide.

Typical Kubernetes Deployment​

A Kubernetes-based deployment in BuildNinja typically follows this sequence:

  1. A build step compiles the application and runs automated tests.
  2. A subsequent step builds a container image and pushes it to a registry.
  3. A deployment step updates the Kubernetes workload using a manifest or image update command.
  4. BuildNinja captures execution output and reports the result of each step.

Each step operates independently and uses Build Parameters to share values such as image tags, registry URLs, and namespaces.

Agent Requirements​

To execute Kubernetes-related build steps, the BuildNinja Agent must have:

  • kubectl installed and available on the system PATH.
  • Access to a valid kubeconfig or environment-based cluster credentials.
  • Network access to the Kubernetes API server of the target cluster.

Next Steps​

  • How to Deploy a Containerized Application to KubernetesConfigure a deployment build configuration in BuildNinja to deploy a pre-built Docker image into a Kubernetes cluster as part of the Continuous Deployment (CD) process.
  • Configure Server and Agent with KubernetesKubernetes provides a scalable and automated way to deploy, manage, and orchestrate BuildNinja Server and Agent across multiple environments.
  • Configure Build ParametersBuildNinja allows you to define Build Parameters that define reusable variables that control how a build executes. These parameters help eliminate hardcoded values inside build steps, improve security, and enable flexibl…