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Plugin System

The plugin system (plugin/) provides protocol-level abstraction for device communication. Plugins implement typed getter/setter interfaces and are composed into charger, meter, or vehicle implementations via configuration.

Plugin Types

Plugin Protocol Key Config
http HTTP/REST uri, method, headers, auth, cache, timeout
mqtt MQTT topic, retained, payload template, timeout
modbus Modbus TCP/RTU uri, register, scale, baudrate, rtu
sunspec SunSpec/Modbus Model-based point queries via device tree
js JavaScript/WASM Inline script evaluation
go Go runtime Dynamic Go code
gpio Linux GPIO Digital I/O for relays

Getter/Setter Interfaces

type StringGetter func() (string, error)
type FloatGetter  func() (float64, error)
type IntGetter    func() (int64, error)
type BoolGetter   func() (bool, error)
// + corresponding Setter types

Pipeline Transforms

Plugins support chained transforms: scale, offset, lookup, regex.

Template-Based Device Configuration

Devices can be defined entirely via YAML templates using plugins:

# templates/definition/charger/example.yaml
status:
  source: http
  uri: http://{{ .host }}/status
enable:
  source: http
  uri: http://{{ .host }}/enable
  method: POST
maxcurrent:
  source: http
  uri: http://{{ .host }}/current/{{ .maxcurrent }}

The generic configurable charger (charger/charger.go) wires these plugin configs into the api.Charger interface at runtime.

Templates render once at config time. HTTP uri and body are templates themselves, evaluated per request (util.ReplaceFormatted: sprig, addDate, timeRound). Defer now to request time with a raw string: {{ `{{ now | date "2006-01-02" }}` }}.

Param Suggestions and Discovery

Template params get suggestions from services (service:), see the service and discovery sections in templates/README.md for the contract. Handlers register in init() via service.Register (server/service/registry.go), object responses use service.Option (util/service/helper.go) and render as Helper/Combobox.vue.

Local network discovery lives in util/discovery (mDNS, SSDP, neighbor table, reverse DNS; no raw sockets, no port scans) and feeds network/hosts, network/report and network/scan in util/service/network*.go. The vendor list is generated from the IEEE registry (make oui-update), see Discovery Hints for the update routine.

  • Scan: 3 s first pass (first request waits), 5 s second pass, repeated when older than a minute, results combined, hosts dropped after 30 minutes.
  • mDNS: browses the types of the template hints plus all types announced in the network (DNS-SD enumeration), so reports show vendor types without a hint.
  • A host keeps all its names (router name first, then mDNS), hostname hints match any of them.
  • EVCC_DISCOVERY_HOSTS (JSON list of discovery.Host) replaces the scan, used in tests and for environments without network access. On macOS the neighbor table is empty for binaries started with go run, test with a built binary.

Key Files

  • plugin/config.go — plugin registry and config types
  • plugin/http.go — HTTP plugin
  • plugin/mqtt.go — MQTT plugin
  • plugin/modbus.go — Modbus plugin
  • plugin/sunspec.go — SunSpec plugin
  • charger/charger.go — generic configurable charger using plugins