CRD

CRD is an acronym that can refer to several concepts in computing and medicine. In computing, it most commonly stands for Custom Resource Definition, a Kubernetes mechanism for extending the API with user-defined resource types.

A CRD defines a resource's name, scope (namespaced or cluster), and schema, and is implemented by a controller or operator that ensures the desired state is reflected in the cluster. Once a CRD is applied, users can create custom resources of that type; their data is stored in etcd and exposed through the Kubernetes API. Features commonly used with CRDs include OpenAPI-based schema validation, versioning, subresources such as status and scale, and optional conversion webhooks for evolving API versions.

In medicine, CRD is also commonly used to denote chronic respiratory disease, a broad category of long-term lung conditions that impair airflow. Diseases in this group include asthma and chronic obstructive pulmonary disease (COPD). Management emphasizes risk factor reduction, vaccination, inhaled bronchodilators and corticosteroids, pulmonary rehabilitation, and regular monitoring.

In some contexts, CRD may also refer to chronic renal disease, a long-standing impairment of kidney function. Chronic renal disease is less standardized as an acronym compared with CKD, but in certain regions and texts it appears as CRD. Care focuses on preserving kidney function, managing blood pressure and diabetes, and planning for potential dialysis or transplantation if progression occurs.