Custom resource definition
A CustomResourceDefinition is a Kubernetes API object that defines a custom resource type and its schema.
Acing the Certified Kubernetes Administrator Exam, Second Edition
A custom resource definition is a Kubernetes API object that defines a new custom resource type and its schema.
- How it is used
- Extends the Kubernetes API with resource types that operators can manage as part of running applications.
- How deep it goes
- Explains CRD fields, scope, installation, discovery, and CR creation; directs field inspection to kubectl explain rather than unpacking generated schemas.
- Examples
- Uses CloudNativePG installation, a PostgreSQL Cluster manifest, kubectl discovery commands, and cluster-status checks.
- What you can do after
- Operate/configure it by installing an operator’s CRDs, inspecting available fields, creating a custom resource, and verifying its resulting workload.
Server-Side WebAssembly
A custom resource definition is a Kubernetes API declaration that extends the Kubernetes API with a new custom resource type.
- How it is used
- Extends Kubernetes so Wasm platforms can declare and orchestrate application-specific resources through familiar API workflows.
- How deep it goes
- Explains CRD registration, custom-resource application, operator reconciliation, and concrete SpinKube and wasmCloud deployment workflows.
- Examples
- Uses Crossplane databases, KubeVirt virtual machines, SpinKube resources, and a wasmCloud Application deployed with kubectl.
- What you can do after
- Operate/configure CRD-backed Wasm deployments with kubectl, Helm, SpinKube, and wasmCloud status or inspection commands.
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Kubernetes in Action, Second Edition
A CustomResourceDefinition is a Kubernetes API object that extends the Kubernetes API with a new custom resource type.
- How it is used
- Extends the Kubernetes API for Gateway networking resources and operator-managed application resources.
- How deep it goes
- Explains installation, release channels, custom objects, reconciliation, and cleanup, but does not detail CRD schema implementation.
- Examples
- Uses Gateway API CRDs and a MongoDBCommunity CRD, with kubectl installation, inspection, reconciliation, and deletion commands.
- What you can do after
- Operate custom API types by installing CRDs, creating custom resources, inspecting them, and removing them during cleanup.
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Designing Deep Learning Systems: A guide for software engineers
A Kubernetes API extension that defines a custom resource kind and its schema.
- How it is used
- Extends Kubernetes with declarative API objects that operators can reconcile into running services, pods, and other resources.
- How deep it goes
- Explains the desired-versus-observed state loop, resource provisioning, status updates, and pod failover without detailing schema fields.
- Examples
- Uses TFJob, PyTorchJob, MPIJob, and Argo Workflow objects to demonstrate training and workflow execution.
- What you can do after
- Operate/configure Kubernetes-native training and workflow systems by submitting CRD objects and inspecting reconciled resources and status.
Kubernetes for Developers
A custom resource definition is a Kubernetes API extension that introduces a new resource type with a user-defined schema.
- How it is used
- Extends Kubernetes when built-in resources cannot express particular business logic or application constructs.
- How deep it goes
- Explains the purpose of custom resource definitions and operator patterns but stops short of implementation details.
- Examples
- Uses unsupported business logic and new constructs as motivating cases, contrasting them with ordinary web application deployment.
- What you can do after
- Build it from scratch by creating a Kubernetes-style API for requirements that built-in Kubernetes resources do not support.
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Kafka for Architects
A custom resource definition is a Kubernetes API extension that declares a new resource type and its schema.
- How it is used
- Represents Kafka artifacts as Kubernetes resources within a GitOps-managed Kafka deployment.
- How deep it goes
- Traces the YAML-to-Git-to-operator reconciliation flow without detailing CRD schema design or controller implementation.
- Examples
- Uses YAML definitions for Kafka topics, connectors, ACLs, and other resources.
- What you can do after
- Operate/configure Kafka resources through Git-backed Kubernetes reconciliation and an operator.
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Logs and Telemetry
A custom resource definition is a Kubernetes API extension that defines a new custom resource type.
- How it is used
- Extends Kubernetes so Fluent Operator components can be deployed and configured through declarative resources.
- How deep it goes
- Defines several resource roles and shows selector-based configuration, but does not detail CRD schema authoring or controller internals.
- Examples
- Uses FluentBit, ClusterFluentBitConfig, and FluentBitConfig resources with enabled-label selectors for logging inputs, filters, and outputs.
- What you can do after
- Operate Fluent Bit through Kubernetes resources that select and assemble logging components.
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Related concepts
- Kubernetesused by · Kubernetes is an open-source platform for orchestrating and automating the deployment, scaling, and management of containerized workloads across computing clusters.
- Fluent Operatorused by · Fluent Operator is a Kubernetes operator for deploying and managing Fluent Bit configurations and resources.
- KServeproduced by · KServe is an open-source Kubernetes-native platform for deploying and serving machine-learning models through standardized resources and interfaces.
- wasmCloudconfigures · wasmCloud is a platform for deploying and coordinating WebAssembly components with distributed capability providers and hosts.
- cert-managerproduced by · cert-manager is a Kubernetes add-on that automates obtaining, issuing, renewing, and deploying TLS certificates from certificate authorities and other issuers.
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