Glossary

Overview

This glossary defines key terms and acronyms used throughout the AgileTV CDN Manager (ESB3027) documentation.

A

ACD (Agile Content Delivery)

The overall CDN solution comprising the Manager (ESB3027) and Director (ESB3024) components.

Agent Node

A Kubernetes node that runs workloads but does not participate in the control plane. Agent nodes provide additional capacity for running application pods.

API Gateway

See NGinx Gateway.

ASN (Autonomous System Number)

A unique identifier for a network on the internet. Used in GeoIP-based routing decisions.

C

CDN Director

The Edge Server Business (ESB3024) component that handles actual content routing and delivery. Multiple Directors can be managed by a single CDN Manager.

Cloudnative PG (CNPG)

A Kubernetes operator that manages PostgreSQL clusters. Provides high availability, automatic failover, and backup capabilities for the Manager’s database layer.

Confd

Configuration daemon that synchronizes configuration from the Manager to CDN Directors. Runs as a sidecar or separate deployment.

CORS (Cross-Origin Resource Sharing)

A security mechanism that allows web applications to make requests to a different domain. Zitadel enforces CORS policies requiring the external domain to match the configured hostname.

CrashLoopBackOff

A Kubernetes pod state indicating the container is repeatedly crashing and being restarted. Typically indicates a configuration or dependency issue.

D

Datastore

The internal key-value storage system used by the Manager for short-lived or simple structured data. Backed by Redis.

Descheduler

A Kubernetes component that periodically analyzes pod distribution and evicts pods from overutilized nodes to optimize cluster balance.

Director

See CDN Director.

E

EDB (EnterpriseDB)

A company that provides PostgreSQL-related software and services. The Cloudnative PG operator was originally developed by EDB.

Ephemeral Storage

Temporary storage available to pods. Used for temporary files and caches. Not persistent across pod restarts.

ESB (Edge Server Business)

The product family designation for CDN components. ESB3027 is the Manager, ESB3024 is the Director.

etcd

A distributed key-value store used by Kubernetes for cluster state management. Runs on Server nodes as part of the control plane.

F

FailedScheduling

A Kubernetes event indicating a pod could not be scheduled due to insufficient resources or scheduling constraints.

Flannel

A network overlay solution for Kubernetes. Provides VXLAN-based networking for pod-to-pod communication.

Frontend GUI

See MIB Frontend.

G

GeoIP

Geographic IP lookup service using MaxMind databases. Used for location-based routing decisions.

Grafana

A visualization and dashboard platform for time-series data. Used to display metrics collected by Telegraf and stored in VictoriaMetrics.

H

Helm Chart

A package of pre-configured Kubernetes resources. The CDN Manager is deployed via a Helm chart that handles all component installation.

HPA (Horizontal Pod Autoscaler)

A Kubernetes feature that automatically scales the number of pods based on CPU/memory utilization or custom metrics.

HTTP Server

The main API server component of the Manager, built with Actix Web (Rust framework).

I

Ingress

A Kubernetes resource that exposes HTTP/HTTPS routes from outside the cluster to services within. The CDN Manager uses Traefik as the ingress controller.

Ingress Controller

A component that implements ingress rules. The CDN Manager uses Traefik for primary ingress and NGinx for external Director communication.

K

Kafka

A distributed event streaming platform used by the Manager for asynchronous communication and event processing.

K3s

A lightweight Kubernetes distribution optimized for edge and production deployments. Used as the underlying cluster technology.

Kubernetes (K8s)

An open-source container orchestration platform. The CDN Manager runs on a K3s-based Kubernetes cluster.

L

Longhorn

A distributed block storage system for Kubernetes. Provides persistent volumes for stateful components like PostgreSQL and Kafka.

Liveness Probe

A Kubernetes health check that determines if a container is running properly. Failed liveness probes trigger container restart.

M

Manager

The central management component (ESB3027) for configuring and monitoring CDN Directors.

MaxMind

A provider of IP intelligence databases including GeoIP City, GeoLite2 ASN, and Anonymous IP databases used by the Manager.

MIB Frontend

The web-based configuration GUI for CDN operators. Provides a user interface for managing streams, routers, and other configuration.

Multi-Factor Authentication (MFA)

An authentication method requiring multiple forms of verification. Note: MFA is not currently supported in the CDN Manager and should be skipped during setup.

N

Name-based Virtual Hosting

A technique where multiple hostnames are served from the same IP address. Zitadel uses this for CORS validation.

Namespace

A Kubernetes abstraction for organizing cluster resources. The CDN Manager uses namespaces to group related components.

NGinx Gateway

An NGinx-based gateway that handles external communication with CDN Directors.

Node Token

A secret token used to authenticate new nodes joining a K3s cluster. Located at /var/lib/rancher/k3s/server/node-token on Server nodes.

O

Operator

A method of packaging, deploying, and managing a Kubernetes application. Cloudnative PG is an operator for PostgreSQL.

OOMKilled

A Kubernetes pod state indicating the container was terminated due to exceeding memory limits.

P

PDB (Pod Disruption Budget)

A Kubernetes feature that ensures a minimum number of pods remain available during voluntary disruptions like maintenance.

PersistentVolume (PV)

A piece of storage in the Kubernetes cluster. Created dynamically by Longhorn for stateful components.

PersistentVolumeClaim (PVC)

A request for storage by a pod. Bound to a PersistentVolume.

Pod

The smallest deployable unit in Kubernetes. Contains one or more containers.

PostgreSQL

An open-source relational database. Used by the Manager for persistent data storage, managed by Cloudnative PG.

Probe

A Kubernetes health check mechanism. Types include liveness, readiness, and startup probes.

Prometheus

An open-source monitoring and alerting toolkit. Telegraf exports metrics in Prometheus format.

R

RBAC (Role-Based Access Control)

A method of regulating access to resources based on user roles. Used by Kubernetes for authorization.

Readiness Probe

A Kubernetes health check that determines if a container is ready to receive traffic. Failed readiness probes remove the pod from service load balancing.

Redis

An in-memory data structure store used for caching and as the datastore backend for the Manager.

Replica

A copy of a pod. Multiple replicas provide high availability and load distribution.

Resource Preset

Predefined resource configurations (nano, micro, small, medium, large, xlarge, 2xlarge) for common deployment sizes.

Rolling Update

A deployment strategy that updates pods one at a time to maintain availability during upgrades.

S

Selection Input

A key-value storage mechanism used for configuration data that can be queried with wildcard patterns. Available in v1 and v2 APIs with different semantics.

Server Node

A Kubernetes node that participates in the control plane (etcd, API server). Can also run workloads unless tainted.

Service

A Kubernetes abstraction that defines a logical set of pods and a policy for accessing them. Provides stable networking endpoints.

ServiceAccount

A Kubernetes identity for processes running in pods. Used for authentication between Kubernetes components.

StatefulSet

A Kubernetes workload API object for managing stateful applications. Used for PostgreSQL and Kafka deployments.

Startup Probe

A Kubernetes health check that determines if a container application has started. Disables liveness and readiness checks until it succeeds.

Stream

A content stream configuration defining source and routing parameters.

T

Telegraf

An agent for collecting, processing, aggregating, and writing metrics. Runs on each node to gather system and application metrics.

TLS (Transport Layer Security)

A cryptographic protocol for secure communication. The CDN Manager uses TLS for all external HTTPS connections.

Topology Aware Hints

A Kubernetes feature that prefers routing traffic to pods in the same zone as the source. Reduces latency by keeping traffic local.

Traefik

A modern HTTP reverse proxy and ingress controller. Used as the primary ingress controller for the CDN Manager.

TTL (Time To Live)

The duration after which data expires. Used in the datastore and selection input APIs.

V

Values.yaml

The Helm chart configuration file. Contains all configurable parameters for the CDN Manager deployment.

VictoriaMetrics

A time-series database used for storing metrics data. Provides long-term storage and querying capabilities.

VXLAN

Virtual Extensible LAN. A network virtualization technology used by Flannel for pod networking.

Z

Zitadel

An identity and access management (IAM) platform used for authentication and authorization in the CDN Manager. Provides OAuth2/OIDC capabilities.

Default Credentials

The following table lists all default credentials used by the CDN Manager. Change these defaults before deploying to production.

Security Warning: These are default credentials only. For production deployments, you must change all default passwords before exposing the system to users.

Zitadel Default Account: Use the default admin@agiletv.dev account only to create a new administrator account with proper roles. After verifying the new account works, disable or delete the default admin account. For details on required roles and administrator permissions, see Zitadel’s Administrator Documentation. See the Next Steps Guide for initial configuration procedures.

Common Abbreviations

Next Steps

After reviewing terminology:

1. Architecture Guide - Understand component relationships
2. Configuration Guide - Full configuration reference
3. Operations Guide - Day-to-day operational procedures