Moved printing into its own separate project called frank. It also has its own toml and deployement system.

It also works on a raspberry pi

frank/config.py

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+from dotenv import load_dotenv
+from pydantic import BaseSettings
+
+
+class Settings(BaseSettings):
+    REDIS_HOST: str = "127.0.0.1"
+    REDIS_PORT: int = 6379
+    QUEUE_NAME: str = "arq:queue"
+
+    class Config:
+        case_sensitive = True
+        env_file = ".env"
+
+
+load_dotenv()
+settings = Settings()

frank/printing.py

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+import re  # noqa: F401
+import socket  # noqa: F401
+import sys  # noqa: F401
+
+from arq import Retry
+
+
+async def sent_to_printer(ctx: dict, data: str, address: str, cut_code: str):
+    address = "/printer"
+    try:
+        print("Printing to :", address, "\n", data, "\n")
+        with open(address, "w") as printer:
+            printer.write(data)
+            printer.write("\n")
+            print(cut_code)
+            printer.write(cut_code)
+    except LookupError as e:
+        print("Lookup error:", e)
+        raise Retry(defer=ctx["job_try"] * 30)
+    except FileNotFoundError as e:
+        print("File not found error:", e)
+        raise Retry(defer=ctx["job_try"] * 30)
+    except:  # noqa: E722
+        print("Unexpected error:", sys.exc_info()[0])
+        # retry the job with increasing back-off
+        # delays will be 5s, 10s, 15s, 20s
+        # after max_tries (default 5) the job will permanently fail
+        raise Retry(defer=ctx["job_try"] * 30)
+
+    # GS = "\x1d"
+    # PAPER_CUT = GS + "V"
+    # # For the printer ESC/POS Reference
+    # # https://reference.epson-biz.com/modules/ref_escpos/index.php?content_id=87
+    # # The m codes are in decimal and can be converted using the following table
+    # # https://www.eso.org/~ndelmott/ascii.html
+    # # The \x03 in all the following is to feed 3 lines before cut it can be increased or reduced
+    # FUNCTION_B_FULL_CUT = "\x41\x03"
+    # FUNCTION_B_PARTIAL_CUT = "\x42\x03"

frank/pyproject.toml

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+[tool.poetry]
+name = "frank"
+version = "7.3.0"
+description = "Point of Sale for a restaurant"
+authors = ["tanshu <git@tanshu.com>"]
+
+[tool.poetry.dependencies]
+python = "^3.8"
+pydantic = {extras = ["dotenv"], version = "^1.8.1"}
+arq = "^0.19.1"
+aiohttp = "^3.7.4"
+
+[build-system]
+requires = ["poetry-core>=1.0.0"]
+build-backend = "poetry.core.masonry.api"

frank/settings.py

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+from arq.connections import RedisSettings
+from config import settings as sett
+
+settings = RedisSettings(host=sett.REDIS_HOST, port=sett.REDIS_PORT)

frank/worker-start.sh

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+#! /usr/bin/env bash
+set -e
+
+echo arq worker.WorkerSettings
+arq worker.WorkerSettings

frank/worker.py

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+import sys
+
+from aiohttp import ClientSession
+from config import settings as sett
+from printing import sent_to_printer
+from settings import settings
+
+sys.path.extend(["./"])
+
+
+async def startup(ctx):
+    ctx["session"] = ClientSession()
+    print(f"Worker listening for: {sett.QUEUE_NAME}")
+    # print(f"Worker printing on: {sett.WORKER_PRINTER_ADDRESS}")
+
+
+async def shutdown(ctx):
+    await ctx["session"].close()
+
+
+class WorkerSettings:
+    """
+    Settings for the ARQ worker.
+    """
+
+    queue_name = f"barker:print:{sett.QUEUE_NAME}"
+    redis_settings = settings
+    functions: list = [sent_to_printer]
+    on_startup = startup
+    on_shutdown = shutdown