AP-859 add basic worker task

Dockerfile

@@ -9,7 +9,7 @@ RUN apt-get update -y && apt-get upgrade -y \
         gcc \
         libpq-dev \
         libxml2-dev \
-        python3-dev \ 
+        python3-dev \
         postgresql-client \
     && rm -rf /var/lib/apt/lists/
 
@@ -45,3 +45,20 @@ RUN pip install --no-cache-dir -e .
 EXPOSE 8000
 
 CMD ["gunicorn", "-w", "4", "-b", "0.0.0.0", "quiabo:app"]
+
+FROM app AS worker
+
+USER root
+
+RUN apt-get update -y \
+    && apt-get install -y --no-install-recommends \
+        tesseract-ocr \
+        tesseract-ocr-eng \
+        tesseract-ocr-spa \
+        tesseract-ocr-deu \
+        tesseract-ocr-chi-tra \
+        tesseract-ocr-ita \
+        tesseract-ocr-fra \
+    && rm -rf /var/lib/apt/lists/*
+
+USER $APP_USER

docker-compose.yml

@@ -13,7 +13,6 @@ x-quiabo-common:
     QUIABO_CELERY__task_default_queue: ${QUIABO_CELERY__task_default_queue:-quiabo}
     QUIABO_CELERY__task_ignore_result: ${QUIABO_CELERY__task_ignore_result:-false}
 
-
 services:
   db:
     environment:
@@ -39,7 +38,7 @@ services:
       redis:
         condition: service_healthy
     environment:
-      <<: 
+      <<:
         - *quiabo-common-environment
         - *dbconfig
     init: true
@@ -48,10 +47,12 @@ services:
       - 8000:8000
     volumes:
       - ./quiabo:/app/quiabo:rw
+      - ./test:/app/test:rw
 
   worker:
     build:
       context: .
+      target: worker
     depends_on:
       db:
         condition: service_healthy
@@ -66,6 +67,7 @@ services:
     command: celery -A quiabo.celery_app worker --loglevel INFO
     volumes:
       - ./quiabo:/app/quiabo:rw
+      - ./files:/app/files:rw
 
   flower:
     build:

quiabo/celery.py

@@ -32,5 +32,6 @@ def __call__(self, *args: object, **kwargs: object) -> object:
     celery_app = Celery(app.name, task_cls=FlaskTask)
     celery_app.config_from_object(app.config["CELERY"])
     celery_app.set_default()
+    celery_app.autodiscover_tasks(["quiabo"], force=True)
     app.extensions["celery"] = celery_app
     return celery_app

quiabo/tasks.py

@@ -0,0 +1,28 @@
+"""Celery tasks for running OCR jobs."""
+
+import subprocess
+from pathlib import Path
+
+from celery import shared_task
+
+
+@shared_task(bind=True)
+def run_tesseract_job(self, filelist: str, languages: list[str], output: str) -> dict:
+    """Run Tesseract over the files listed in filelist and write output PDF."""
+
+    output = output.removesuffix(".pdf")
+
+    output_dir = Path(output).parent
+    if not output_dir.exists():
+        raise FileNotFoundError(f"Output directory {output_dir} does not exist.")
+
+    # The state update does not need any meta, unless we want it for debugging or tracking.
+    self.update_state(
+        state="STARTED",
+        meta={"filelist": filelist, "languages": languages, "output": output},
+    )
+
+    command = ["tesseract", "-l", "+".join(languages), filelist, output, "pdf"]
+    subprocess.run(command, check=True, capture_output=True, text=True)
+
+    return {"output": f"{output}.pdf"}

test/fixtures/files/files.txt

@@ -0,0 +1 @@
+/app/test/fixture/files/testocr.png

test/unit/test_tasks.py

@@ -0,0 +1,84 @@
+"""Unit tests for the shared task defined in ``tasks.py``."""
+
+from unittest.mock import Mock
+
+from quiabo.tasks import run_tesseract_job
+
+
+def test_shared_task_is_registered():
+    """Verify that the Tesseract task is registered with Celery."""
+    task = run_tesseract_job
+
+    assert task.name
+    assert task.app.tasks[task.name].name == task.name
+    assert callable(task.run)
+
+
+def test_shared_task_delay_delegates_to_apply_async(monkeypatch):
+    """Verify that delaying the task delegates to ``apply_async``."""
+    apply_async = Mock(return_value="queued")
+    monkeypatch.setattr(run_tesseract_job, "apply_async", apply_async)
+
+    result = run_tesseract_job.delay("filelist.txt", ["eng", "spa"], "output")
+
+    assert result == "queued"
+    apply_async.assert_called_once_with(
+        ("filelist.txt", ["eng", "spa"], "output"),
+        {},
+    )
+
+
+def test_run_tesseract_job_updates_state_and_runs_tesseract(monkeypatch):
+    """Verify that the task updates state and invokes Tesseract."""
+    update_state = Mock()
+    run = Mock()
+    monkeypatch.setattr(run_tesseract_job, "update_state", update_state)
+    monkeypatch.setattr("quiabo.tasks.subprocess.run", run)
+
+    result = run_tesseract_job.run(
+        "files.txt",
+        ["eng", "spa"],
+        "output",
+    )
+
+    update_state.assert_called_once_with(
+        state="STARTED",
+        meta={
+            "filelist": "files.txt",
+            "languages": ["eng", "spa"],
+            "output": "output",
+        },
+    )
+    run.assert_called_once_with(
+        ["tesseract", "-l", "eng+spa", "files.txt", "output", "pdf"],
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    assert result == {"output": "output.pdf"}
+
+
+def test_run_tesseract_job_removes_pdf_suffix(monkeypatch):
+    """Verify that an existing PDF suffix is removed before invocation."""
+    update_state = Mock()
+    run = Mock()
+    monkeypatch.setattr(run_tesseract_job, "update_state", update_state)
+    monkeypatch.setattr("quiabo.tasks.subprocess.run", run)
+
+    result = run_tesseract_job.run("files.txt", ["eng"], "output.pdf")
+
+    update_state.assert_called_once_with(
+        state="STARTED",
+        meta={
+            "filelist": "files.txt",
+            "languages": ["eng"],
+            "output": "output",
+        },
+    )
+    run.assert_called_once_with(
+        ["tesseract", "-l", "eng", "files.txt", "output", "pdf"],
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    assert result == {"output": "output.pdf"}