openapi: 3.0.3
info:
  title: NCPA (Nagios Cross-Platform Agent) API
  description: |
    REST API exposed by the Nagios Cross-Platform Agent (NCPA) running on
    Linux, Windows, or macOS. The API uses a hierarchical node-based URL
    structure (`/api/{module}/{node1}/{node2}`) and is authenticated by a
    `token` query parameter matching the `community_string` in the agent
    config. Both active polls and Nagios-style passive check results are
    supported.
  version: '3.x'
  contact:
    name: Nagios Enterprises
    url: https://www.nagios.org/ncpa/

servers:
  - url: https://{ncpaHost}:5693/api
    description: NCPA agent listening on default TLS port 5693.
    variables:
      ncpaHost:
        default: localhost

security:
  - TokenAuth: []

tags:
  - name: System
    description: Host system identity and agent metadata.
  - name: CPU
    description: System-wide CPU utilization and core counts.
  - name: Memory
    description: Physical memory and swap.
  - name: Disk
    description: Logical, physical, and mount-point disk metrics.
  - name: Interface
    description: Network interface byte and packet counters.
  - name: Processes
    description: Running process inventory and resource use.
  - name: Services
    description: Host service / daemon status.
  - name: Plugins
    description: User-defined Nagios-style plugins executed by the agent.

paths:
  /system:
    get:
      tags: [System]
      summary: Get System Information
      operationId: getSystem
      parameters:
        - $ref: '#/components/parameters/Token'
      responses:
        '200': { description: Host system info.,
                 content: { application/json: { schema: { $ref: '#/components/schemas/MetricResponse' } } } }
  /system/agent_version:
    get:
      tags: [System]
      summary: Get Agent Version
      operationId: getAgentVersion
      parameters:
        - $ref: '#/components/parameters/Token'
      responses:
        '200': { description: NCPA agent version. }
  /cpu/percent:
    get:
      tags: [CPU]
      summary: Get CPU Percent
      operationId: getCpuPercent
      parameters:
        - $ref: '#/components/parameters/Token'
        - name: aggregate
          in: query
          schema: { type: string, enum: [avg, min, max, sum] }
        - $ref: '#/components/parameters/Warning'
        - $ref: '#/components/parameters/Critical'
        - $ref: '#/components/parameters/Check'
      responses:
        '200': { description: CPU utilization. }
  /cpu/count:
    get:
      tags: [CPU]
      summary: Get CPU Core Count
      operationId: getCpuCount
      parameters:
        - $ref: '#/components/parameters/Token'
      responses:
        '200': { description: Number of CPU cores. }
  /memory/virtual:
    get:
      tags: [Memory]
      summary: Get Virtual Memory
      operationId: getMemoryVirtual
      parameters:
        - $ref: '#/components/parameters/Token'
        - $ref: '#/components/parameters/Units'
        - $ref: '#/components/parameters/Warning'
        - $ref: '#/components/parameters/Critical'
        - $ref: '#/components/parameters/Check'
      responses:
        '200': { description: Virtual memory metrics. }
  /memory/swap:
    get:
      tags: [Memory]
      summary: Get Swap Memory
      operationId: getMemorySwap
      parameters:
        - $ref: '#/components/parameters/Token'
        - $ref: '#/components/parameters/Units'
      responses:
        '200': { description: Swap usage. }
  /disk/logical:
    get:
      tags: [Disk]
      summary: Get Logical Disks
      operationId: getDiskLogical
      parameters:
        - $ref: '#/components/parameters/Token'
        - $ref: '#/components/parameters/Units'
        - $ref: '#/components/parameters/Warning'
        - $ref: '#/components/parameters/Critical'
        - $ref: '#/components/parameters/Check'
      responses:
        '200': { description: Logical disk metrics. }
  /disk/physical:
    get:
      tags: [Disk]
      summary: Get Physical Disks
      operationId: getDiskPhysical
      parameters:
        - $ref: '#/components/parameters/Token'
        - $ref: '#/components/parameters/Units'
      responses:
        '200': { description: Physical disk metrics. }
  /disk/mount:
    get:
      tags: [Disk]
      summary: Get Disk Mount Points
      operationId: getDiskMount
      parameters:
        - $ref: '#/components/parameters/Token'
      responses:
        '200': { description: Mount point metadata. }
  /interface:
    get:
      tags: [Interface]
      summary: Get Network Interfaces
      operationId: getInterface
      parameters:
        - $ref: '#/components/parameters/Token'
        - $ref: '#/components/parameters/Units'
        - name: delta
          in: query
          schema: { type: integer, enum: [0, 1] }
          description: When 1, return per-second change rate.
      responses:
        '200': { description: Network interface counters. }
  /processes:
    get:
      tags: [Processes]
      summary: List Processes
      operationId: listProcesses
      parameters:
        - $ref: '#/components/parameters/Token'
        - name: name
          in: query
          schema: { type: string }
        - name: exe
          in: query
          schema: { type: string }
        - name: cmd
          in: query
          schema: { type: string }
        - name: mem_percent
          in: query
          schema: { type: number }
        - name: cpu_percent
          in: query
          schema: { type: number }
      responses:
        '200': { description: Process list. }
  /services:
    get:
      tags: [Services]
      summary: List Services
      operationId: listServices
      parameters:
        - $ref: '#/components/parameters/Token'
        - name: service
          in: query
          schema: { type: string }
        - name: status
          in: query
          schema: { type: string, enum: [running, stopped] }
      responses:
        '200': { description: Service status. }
  /plugins/{pluginName}:
    get:
      tags: [Plugins]
      summary: Run NCPA Plugin
      operationId: runPlugin
      parameters:
        - $ref: '#/components/parameters/Token'
        - name: pluginName
          in: path
          required: true
          schema: { type: string }
        - name: args
          in: query
          schema: { type: string }
      responses:
        '200':
          description: Plugin output (Nagios check result format).
          content:
            application/json:
              schema: { $ref: '#/components/schemas/CheckResult' }

components:
  securitySchemes:
    TokenAuth:
      type: apiKey
      in: query
      name: token
  parameters:
    Token:
      name: token
      in: query
      required: true
      schema: { type: string }
      description: NCPA community_string token from agent config.
    Units:
      name: units
      in: query
      schema: { type: string, enum: [k, Ki, M, Mi, G, Gi, T, Ti] }
      description: Convert byte/bit values to the requested SI or binary unit.
    Warning:
      name: warning
      in: query
      schema: { type: string }
      description: Nagios-style warning threshold (e.g. '80', '90:', '@70:90').
    Critical:
      name: critical
      in: query
      schema: { type: string }
      description: Nagios-style critical threshold.
    Check:
      name: check
      in: query
      schema: { type: integer, enum: [0, 1] }
      description: When 1, return a Nagios-style check result with returncode + stdout.
  schemas:
    MetricResponse:
      type: object
      additionalProperties:
        type: array
        description: '[value, "unit"] pair returned per metric.'
        minItems: 2
        maxItems: 2
        items: {}
    CheckResult:
      type: object
      required: [returncode, stdout]
      properties:
        returncode:
          type: integer
          enum: [0, 1, 2, 3]
          description: 0=OK, 1=WARNING, 2=CRITICAL, 3=UNKNOWN.
        stdout:
          type: string
          example: "OK: 12% CPU usage | 'cpu_percent'=12;80;90;"