Implement Pydantic BaseSettings for Env Vars

Author: ben-burwood

docker-compose.yml

@@ -4,11 +4,24 @@ services:
       context: .
       dockerfile: Dockerfile
     container_name: print_server
+    environment:
+      - BACKEND=${BACKEND}
+      - PRINTER=${PRINTER}
+      - VENDOR_ID=${VENDOR_ID}
+      - PRODUCT_ID=${PRODUCT_ID}
+      - MEDIA=${MEDIA}
+      - FONT=${FONT}
     ports:
       - "80:80"
     privileged: true
     devices:
       - /dev/bus/usb:/dev/usb  # USB Printer
-    # volumes:
+      # volumes:
       # - /sys/class/pwm/pwmchip0/pwm1/:/sys/class/pwm/pwmchip0/pwm1
     restart: always
+    healthcheck:
+      test: [ "CMD", "curl", "-f", "http://localhost:80/health" ]
+      interval: 60s
+      timeout: 10s
+      retries: 2
+      start_period: 30s

web/.env.example

@@ -0,0 +1,11 @@
+BACKEND=usb
+PRINTER=PTP_700
+
+VENDOR_ID=
+PRODUCT_ID=
+
+MOTOR_INITIAL=50
+MOTOR_FINAL=25
+
+MEDIA=W12
+FONT=/root/.local/share/fonts/fonts/ttf/JetBrainsMono-Regular.ttf

web/config.py

@@ -4,35 +4,34 @@
 from fastapi import FastAPI
 from fastapi.staticfiles import StaticFiles
 
-from . import BrotherPrinterApiError
-from .config import Config
 from .printer_manager import PrinterManager
-from .routes.config import router as config_router
 from .routes.print import router as print_router
+from .settings import Settings
 
 app = FastAPI()
 
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
-    config = Config.get()
-    if config.backend is None or config.printer is None:
-        raise BrotherPrinterApiError("Must Provide a Valid Backend AND Printer Configuration")
+    settings = Settings()
 
-    PrinterManager.toggle_power_button(config.motor_initial, config.motor_pressed)
+    PrinterManager.toggle_power_button(settings.motor_initial, settings.motor_final)
     time.sleep(5)
 
-    PrinterManager(config.backend, config.printer, config.vendor_id, config.product_id)
+    PrinterManager(
+        settings.backend, settings.printer, settings.vendor_id, settings.product_id
+    )
 
     yield
 
 
 app.router.lifespan_context = lifespan
-app.include_router(config_router)
 app.include_router(print_router)
 
+
 @app.get("/health")
 def health():
     return {"status": "ok"}
 
+
 app.mount("/", StaticFiles(directory="static", html=True), name="static")

web/config.yaml

@@ -4,7 +4,7 @@
 from brother_label_printer_control.labels.text import Padding, Text
 from pydantic import BaseModel, Field, field_validator
 
-from .config import Config
+from .settings import Settings
 
 
 class PrintRequest(BaseModel):
@@ -13,8 +13,8 @@ class PrintRequest(BaseModel):
     padding: Padding = Field(
         default_factory=lambda: Padding(top=0, right=0, bottom=0, left=0)
     )
-    font: str = Field(default_factory=lambda: Config.get().font)
-    media: Media = Field(default_factory=lambda: Config.get().media)
+    font: str = Field(default_factory=lambda: Settings().font)
+    media: Media = Field(default_factory=lambda: Settings().media)
 
     @field_validator("padding")
     def set_padding(cls, padding: dict[str, int] | Padding) -> Padding:

web/main.py

@@ -1,14 +1,14 @@
 from brother_label_printer_control.job import Job
 from fastapi import APIRouter, Depends
 
-from .config import Config
 from ..print_request import PrintRequest
 from ..printer_manager import PrinterManager
+from ..settings import Settings
 
 router = APIRouter()
 
 
-def get_printer_manager(config: Config = Depends(Config.get)) -> "PrinterManager":
+def get_printer_manager(config: Settings = Depends(Settings)) -> "PrinterManager":
     return PrinterManager(config.backend, config.printer)
 
 

web/print_request.py

@@ -0,0 +1,51 @@
+from brother_label_printer_control.backends.main import Backend
+from brother_label_printer_control.constants import Media
+from brother_label_printer_control.printers.main import Printer
+from brother_label_printer_control.utils.font import get_fonts
+from pydantic import model_validator
+from pydantic_settings import BaseSettings
+
+from . import BrotherPrinterApiError
+
+
+class Settings(BaseSettings):
+    """Get the Settings from the Environment"""
+
+    backend: Backend | None
+    printer: Printer | None
+    vendor_id: int | None
+    product_id: int | None
+    motor_initial: int
+    motor_final: int
+    media: Media | None
+    font: str | None
+
+    @classmethod
+    @model_validator(mode="before")
+    def convert_fields(cls, values):
+        backend_value = values.get("backend")
+        if not backend_value:
+            raise BrotherPrinterApiError("Must Provide a Valid Backend")
+        values["backend"] = Backend.get(backend_value)
+
+        printer_value = values.get("printer")
+        if not printer_value:
+            raise BrotherPrinterApiError("Must Provide a Valid Printer")
+        values["printer"] = Printer.get(printer_value)
+
+        media_value = values.get("media")
+        if media_value:
+            values["media"] = Media.get(media_value)
+
+        if not values.get("font"):
+            values["font"] = cls._get_default_font()
+
+        return values
+
+    @staticmethod
+    def _get_default_font() -> str | None:
+        """Get the First Available TrueType Font in Linux as Default"""
+        try:
+            return list(get_fonts().values())[0][0].as_posix()
+        except IndexError:
+            return None