implement print queue

docker-compose.printer.dev.yml

@@ -0,0 +1,21 @@
+version: '2'
+services:
+  sce-printer:
+    container_name: sce-printer-dev
+    build:
+      context: .
+      dockerfile: ./printer/Dockerfile.printer.dev
+    ports:
+      # we use port 14000 as that is what the website expects
+      # the printing server to be running on
+      - 14000:14000
+    volumes:
+      - ./config:/app/config
+      - ./printer:/app/printer
+      - ./tmp:/tmp
+    command:
+      - --development
+      - --port=14000
+      - --dont-delete-pdfs
+      - --config-json-path=/app/config/config.json
+      - --dev-printer

printer/Dockerfile.printer.dev

@@ -0,0 +1,28 @@
+# Base image from https://github.com/DrPsychick/docker-cups-airprint
+# Docker images are here https://hub.docker.com/r/drpsychick/airprint-bridge/tags
+FROM drpsychick/airprint-bridge:jammy
+
+WORKDIR /app
+RUN apt-get update
+
+RUN apt install -y python3 python3-pip python3-venv jq ssh
+
+# Create the virtual environment with Python
+RUN python3 -m venv /opt/venv
+
+# Set the virtual environment as the default Python environment
+ENV PATH="/opt/venv/bin:$PATH"
+
+COPY ./printer/requirements.txt  /app/printer/requirements.txt
+
+RUN /opt/venv/bin/pip install -r /app/printer/requirements.txt
+
+COPY ./config/config.json /app/config/config.json
+
+COPY ./printer/what_dev.sh /app/printer/what_dev.sh
+
+COPY ./printer/*.py /app/printer/
+
+EXPOSE 9000
+
+ENTRYPOINT ["./printer/what_dev.sh"]

printer/print_queue.py

@@ -0,0 +1,33 @@
+import subprocess
+import time
+import logging
+
+class PrintQueue:
+    _queue = []
+
+    def add(self, file_name):
+        self._queue.append(file_name)
+
+    def in_queue(self, file_name):
+        return file_name in self._queue
+
+    def feed_into_printer(self):
+        while True:
+            time.sleep(1)
+
+            if self._queue.__len__() == 0:
+                continue
+
+            proc = subprocess.Popen(
+                'lpstat -o',
+                shell=True,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE,
+                text=True,
+            )
+
+            printer_job_count = str(proc.stdout.read()).count("\n")
+
+            if printer_job_count <= 2:
+                logging.info("FED REQUEST INTO PRINTER")
+                self._queue.pop(0)

printer/server.py

@@ -7,6 +7,8 @@
 import time
 import uuid
 import collector
+import asyncio
+from print_queue import PrintQueue
 
 from fastapi import FastAPI, File, Form, HTTPException, UploadFile
 from fastapi.middleware.cors import CORSMiddleware
@@ -17,6 +19,7 @@
 from metrics import MetricsHandler
 
 
+print_queue = PrintQueue()
 metrics_handler = MetricsHandler.instance()
 app = FastAPI()
 
@@ -35,7 +38,6 @@
 logging.getLogger("uvicorn.access").setLevel(logging.WARNING)
 logging.getLogger("uvicorn.error").setLevel(logging.WARNING)
 
-
 def get_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser()
     parser.add_argument(
@@ -49,6 +51,12 @@ def get_args() -> argparse.Namespace:
         default=9000,
         help="PORT name for server to listen on. defaults to 9000",
     )
+    parser.add_argument(
+        "--dev-printer",
+        action="store_true",
+        default=False,
+        help="specify if the development virtual printer should be used",
+    )
     parser.add_argument(
         "--config-json-path",
         default="/app/config/config.json",
@@ -110,10 +118,11 @@ def send_file_to_printer(
         maybe_page_range = f"-o page-ranges={page_range}"
 
     # only the right printer works right now, so we default to it
-    PRINTER_NAME = os.environ.get("RIGHT_PRINTER_NAME")
-    command = f"lp -n {num_copies} {maybe_page_range} -o sides={sides} -o media=na_letter_8.5x11in -d {PRINTER_NAME} {file_path}"
+    PRINTER_NAME = "dev_printer" if args.dev_printer else os.environ.get("RIGHT_PRINTER_NAME")
+    command = f"lp -H hold -n {num_copies} {maybe_page_range} -o sides={sides} -o media=na_letter_8.5x11in -d {PRINTER_NAME} {file_path}"
     metrics_handler.print_jobs_recieved.inc()
-    if args.development:
+
+    if args.development and not args.dev_printer:
         logging.warning(
             f"server is in development mode, command would've been `{command}`"
         )
@@ -126,6 +135,7 @@ def send_file_to_printer(
         stderr=subprocess.PIPE,
         text=True,
     )
+
     print_job.wait()
 
     if print_job.returncode != 0:
@@ -145,16 +155,14 @@ def send_file_to_printer(
         # with code 0 but the output could not be parsed for a job id.
         return ''
 
-
 def maybe_delete_pdf(file_path):
     if args.dont_delete_pdfs:
         logging.info(
-            f"--dont-delete-pdfs is set, skipping deletion of file {file_path}"
+           f"--dont-delete-pdfs is set, skipping deletion of file {file_path}"
         )
         return
     pathlib.Path(file_path).unlink()
 
-
 @app.get("/healthcheck/printer")
 def api():
     metrics_handler.last_health_check_request.set(int(time.time()))
@@ -178,6 +186,18 @@ async def read_item(
       "sides": string value from user input on clark frontend; we insert this into the lp command,
     }
     """
+
+    if args.dev_printer or not args.development:
+        print_queue.add(file.filename)
+        timeout = 0
+        while print_queue.in_queue(file.filename):
+            timeout += 1
+
+            if timeout > 120:
+                raise Exception("/print TIMED OUT AFTER 120 SECONDS WHILE WAITING IN THE PRINTER QUEUE")
+
+            await asyncio.sleep(1)
+
     try:
         base = pathlib.Path("/tmp")
         file_id = str(uuid.uuid4())
@@ -201,7 +221,7 @@ async def read_item(
             status_code=500,
             detail="printing failed, check logs",
         )
-
+    
 
 # we have a separate __name__ check here due to how FastAPI starts
 # a server. the file is first ran (where __name__ == "__main__")
@@ -212,6 +232,13 @@ async def read_item(
 # the thread interacts with an instance different than the one the
 # server uses
 if __name__ == "server":
+    if args.dev_printer or not args.development:
+        queue_thread = threading.Thread(
+            target=print_queue.feed_into_printer,
+            daemon=True
+        )
+        queue_thread.start()
+
     if not args.development:
         # set the last time we opened an ssh tunnel to now because
         # when the script runs for the first time, we did so in what.sh

printer/what_dev.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+/root/start-cups.sh > /dev/null 2>&1 & 
+
+sleep 10
+
+lpadmin -p dev_printer -E -v file:///dev/null
+
+python3 /app/printer/server.py $@