58+ DevOps and cloud infrastructure terms explained in plain language.
A
Ansible
An open-source automation tool for configuration management, application deployment, and task automation. Ansible uses YAML-based playbooks and operates agentlessly over SSH, making it simple to get started without installing software on target machines.
A server that acts as the single entry point for a set of microservices. It handles request routing, composition, rate limiting, and authentication so that individual services don't need to implement these concerns themselves.
A declarative GitOps continuous delivery tool for Kubernetes. ArgoCD continuously monitors Git repositories and automatically syncs the desired application state to the cluster, providing a clear audit trail of every deployment.
The ability to automatically adjust the number of running compute resources based on real-time demand. Auto scaling ensures applications can handle traffic spikes without over-provisioning during quiet periods, optimizing both performance and cost.
B
Blue-Green Deployment
A release strategy that runs two identical production environments called 'blue' and 'green.' Traffic is switched from one to the other once the new version is verified, enabling instant rollback by redirecting traffic back to the previous environment.
C
Canary Release
A deployment technique where a new version is rolled out to a small subset of users before being promoted to the entire fleet. This limits the blast radius of bugs and allows teams to monitor real-world performance before full rollout.
CI/CD
Continuous Integration and Continuous Delivery/Deployment — the practice of automating the build, test, and release process. CI merges code changes frequently and runs automated tests, while CD ensures those changes are reliably delivered to production.
A Kubernetes object used to store non-confidential configuration data as key-value pairs. ConfigMaps decouple configuration from container images, allowing the same image to be used across different environments with different settings.
A lightweight, standalone package that includes everything needed to run a piece of software — code, runtime, libraries, and system tools. Containers share the host OS kernel, making them far more efficient than traditional virtual machines.
A repository for storing and distributing container images. Registries like Docker Hub, GitHub Container Registry, and Amazon ECR allow teams to push, pull, and version their images as part of the CI/CD pipeline.
A Kubernetes controller that ensures a copy of a specific Pod runs on every (or selected) node in the cluster. DaemonSets are commonly used for node-level concerns like log collection agents, monitoring exporters, and network proxies.
A Kubernetes resource that manages a set of identical Pods and provides declarative updates, rolling rollouts, and automatic rollbacks. Deployments are the standard way to run stateless applications on Kubernetes.
A platform for building, shipping, and running applications inside containers. Docker uses OS-level virtualization to deliver software in portable, reproducible packages that work identically across development, staging, and production.
A tool for defining and running multi-container Docker applications using a YAML configuration file. With a single command you can spin up all the services your app needs — databases, caches, workers — in an isolated environment.
Docker's built-in container orchestration tool that turns a pool of Docker hosts into a single virtual host. Swarm provides service discovery, load balancing, and rolling updates with a simpler learning curve than Kubernetes.
Amazon Elastic Container Service — a fully managed container orchestration service from AWS. ECS lets you run Docker containers at scale without managing the underlying infrastructure, integrating tightly with other AWS services like ALB and CloudWatch.
Amazon Elastic Kubernetes Service — a managed Kubernetes service that runs the Kubernetes control plane across multiple AWS availability zones. EKS removes the operational burden of maintaining your own Kubernetes master nodes.
A high-performance, open-source edge and service proxy designed for cloud-native applications. Envoy handles load balancing, observability, and TLS termination, and is the data plane behind popular service meshes like Istio.
F
Firewall
A network security system that monitors and controls incoming and outgoing traffic based on predetermined rules. In cloud environments, firewalls are often implemented as security groups or network ACLs that restrict access to specific ports and IP ranges.
G
Git
A distributed version control system that tracks changes in source code during development. Git enables branching, merging, and collaboration, and is the foundation of modern DevOps workflows including GitOps and CI/CD pipelines.
An operational framework where Git repositories serve as the single source of truth for both application code and infrastructure configuration. Changes are applied through pull requests and automatically reconciled by controllers running in the cluster.
An open-source analytics and visualization platform commonly used for monitoring dashboards. Grafana connects to data sources like Prometheus, Loki, and Elasticsearch, allowing teams to create rich, interactive dashboards for metrics and logs.
An endpoint or mechanism that reports whether a service is running correctly. Health checks are used by load balancers, orchestrators, and monitoring systems to detect failures and automatically route traffic away from unhealthy instances.
Helm
A package manager for Kubernetes that uses templated YAML files called 'charts' to define, install, and upgrade applications. Helm simplifies complex deployments by bundling related Kubernetes resources into a single, versioned package.
Horizontal Pod Autoscaler — a Kubernetes resource that automatically scales the number of Pod replicas based on observed CPU utilization, memory usage, or custom metrics. HPA enables applications to handle variable workloads without manual intervention.
A property of an operation meaning it produces the same result whether executed once or multiple times. Idempotency is critical in DevOps for configuration management, API design, and deployment scripts where retries must be safe.
A read-only template used to create containers. A container image packages application code, runtime, libraries, and dependencies into a single artifact that can be versioned, shared via registries, and run identically on any compatible host.
An approach where servers or containers are never modified after deployment. Instead of patching running systems, you build a new image with the changes and replace the old instances entirely, eliminating configuration drift and improving reliability.
The practice of managing and provisioning infrastructure through machine-readable configuration files rather than manual processes. IaC tools like Terraform and Ansible make infrastructure reproducible, version-controlled, and auditable.
A Kubernetes resource that manages external HTTP and HTTPS access to services within a cluster. Ingress controllers handle TLS termination, name-based virtual hosting, and path-based routing, acting as the gateway between the internet and your services.
An open-source automation server widely used for building CI/CD pipelines. Jenkins supports hundreds of plugins for integration with virtually every tool in the DevOps ecosystem, though it requires more operational overhead than newer alternatives.
An open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications across clusters of machines. Kubernetes has become the de facto standard for running production container workloads.
A Kubernetes health check that determines whether a container is still running. If the liveness probe fails, the kubelet kills the container and restarts it according to the pod's restart policy, helping recover from deadlocks and hung processes.
A device or software component that distributes incoming network traffic across multiple servers to ensure no single server becomes overwhelmed. Load balancers improve availability, reliability, and responsiveness of applications.
The practice of recording events, errors, and informational messages from applications and infrastructure. Centralized logging with tools like the ELK stack or Loki is essential for debugging, auditing, and understanding system behavior in production.
An architectural pattern where an application is composed of small, independently deployable services, each responsible for a single business capability. Microservices enable teams to develop, deploy, and scale services independently.
N
Namespace
A mechanism in Kubernetes for isolating groups of resources within a single cluster. Namespaces allow multiple teams or environments to coexist on the same cluster while providing logical boundaries for access control and resource quotas.
A high-performance web server, reverse proxy, and load balancer. Nginx is widely used in DevOps for serving static content, terminating TLS, proxying requests to application servers, and acting as an Ingress controller in Kubernetes.
A physical or virtual machine in a Kubernetes cluster that runs workloads. Each node runs the kubelet agent, a container runtime, and the kube-proxy. Nodes are managed by the control plane and can be added or removed to scale the cluster.
The ability to understand a system's internal state through its external outputs — metrics, logs, and traces. Observability goes beyond traditional monitoring by enabling engineers to ask arbitrary questions about system behavior without deploying new instrumentation.
The automated coordination and management of multiple containers, services, or infrastructure components. Container orchestrators like Kubernetes handle scheduling, scaling, networking, and self-healing across clusters of machines.
A Kubernetes storage abstraction that provides durable storage independent of any individual Pod's lifecycle. PersistentVolumes are provisioned by administrators or dynamically by StorageClasses, and claimed by Pods through PersistentVolumeClaims.
An automated sequence of stages that code passes through from commit to production. A typical pipeline includes building, testing, security scanning, staging deployment, and production release, with gates between each stage.
The smallest deployable unit in Kubernetes, consisting of one or more containers that share networking and storage. Pods are ephemeral by design — they can be created, destroyed, and replaced at any time by higher-level controllers like Deployments.
An open-source monitoring and alerting toolkit that collects and stores time-series metrics data. Prometheus uses a pull model to scrape metrics from instrumented targets and provides a powerful query language (PromQL) for analysis and alerting.
A Kubernetes health check that determines whether a container is ready to accept traffic. Unlike liveness probes, a failing readiness probe doesn't restart the container — it simply removes the Pod from the Service's endpoint list until it recovers.
A Kubernetes controller that ensures a specified number of identical Pod replicas are running at all times. While ReplicaSets are rarely created directly (Deployments manage them), they are the underlying mechanism for horizontal scaling.
A deployment strategy that incrementally replaces instances of the old version with the new version, one at a time. Rolling updates ensure zero downtime by keeping a minimum number of healthy instances available throughout the process.
S
Secret
A Kubernetes object for storing sensitive data such as passwords, tokens, and TLS certificates. Secrets are base64-encoded by default and can be mounted as files or injected as environment variables, keeping sensitive values out of container images.
A Kubernetes abstraction that provides stable networking for a set of Pods. Services assign a fixed IP address and DNS name to a logical group of Pods, enabling reliable communication even as individual Pods are created and destroyed.
A dedicated infrastructure layer for managing service-to-service communication within a microservices architecture. Service meshes like Istio and Linkerd provide traffic management, mutual TLS, observability, and resilience features without changing application code.
SLA/SLO/SLI
Service Level Agreement, Objective, and Indicator — a hierarchy of reliability metrics. SLIs measure specific aspects of service performance, SLOs set target values for those indicators, and SLAs are contractual commitments with consequences for violations.
Secure Shell — a cryptographic network protocol for operating network services securely over an unsecured network. SSH is the standard method for remotely accessing Linux servers, transferring files, and tunneling other protocols.
A Kubernetes controller for managing stateful applications that require stable network identities, ordered deployment, and persistent storage. StatefulSets are used for databases, message queues, and other workloads where identity and data persistence matter.
An open-source Infrastructure as Code tool by HashiCorp that lets you define and provision cloud infrastructure using declarative configuration files (HCL). Terraform manages the full lifecycle of resources and supports hundreds of cloud providers.
A tool by HashiCorp for securely storing and managing secrets, encryption keys, and certificates. Vault provides dynamic secrets, automatic rotation, and fine-grained access control, making it a central component of enterprise security architectures.
Volume
A directory accessible to containers in a Pod, used for persisting data beyond the container's lifecycle. Kubernetes supports many volume types including hostPath, NFS, and cloud provider disks, each with different durability and performance characteristics.
A deployment strategy where new versions are released without any service interruption to end users. Techniques include rolling updates, blue-green deployments, and canary releases, all of which ensure availability during the transition between versions.
