bug(medcat-demo-app): CU-869azbdfh Fail without model (#197)

* CU-869azbdfh: Avoid running the container without a loaded model

* CU-869azbdfh: Remove unused env variables

* CU-869azbdfh: Avoid loading model pack at module import

Author: mart-r

medcat-demo-app/webapp/Dockerfile

@@ -55,13 +55,6 @@ COPY --from=build /webapp /webapp
 # Copy Python site-packages (installed by pip) from build stage
 COPY --from=build /usr/local/lib/python3.12/site-packages /usr/local/lib/python3.12/site-packages
 
-# Set environment variables
-ENV VOCAB_URL=https://medcat.rosalind.kcl.ac.uk/media/vocab.dat
-ENV CDB_URL=https://medcat.rosalind.kcl.ac.uk/media/cdb-medmen-v1.dat
-
-ENV CDB_PATH=/webapp/models/cdb.dat
-ENV VOCAB_PATH=/webapp/models/vocab.dat
-
 # Set the pythonpath
 WORKDIR /webapp
 

medcat-demo-app/webapp/demo/views.py

@@ -10,13 +10,12 @@
 from wsgiref.util import FileWrapper
 from medcat import __version__ as medcat_version
 from medcat.cat import CAT
-from medcat.cdb import CDB
-from medcat.vocab import Vocab
 from urllib.request import urlretrieve, urlopen
 from urllib.error import HTTPError
 #from medcat.meta_cat import MetaCAT
 from .models import *
 from .forms import DownloaderForm, UMLSApiKeyForm
+from functools import lru_cache
 
 AUTH_CALLBACK_SERVICE = 'https://medcat.rosalind.kcl.ac.uk/auth-callback'
 VALIDATION_BASE_URL = 'https://uts-ws.nlm.nih.gov/rest/isValidServiceValidate'
@@ -29,10 +28,10 @@
 
 model_pack_path = os.getenv('MODEL_PACK_PATH', 'models/medmen_wstatus_2021_oct.zip')
 
-try:
-    cat = CAT.load_model_pack(model_pack_path)
-except Exception as e:
-    print(str(e))
+
+@lru_cache
+def get_model_pack():
+    return CAT.load_model_pack(model_pack_path)
 
 
 TPL_ENT = """<mark class="entity" v-on:click="show_info({id})" style="background: {bg}; padding: 0.12em 0.6em; margin: 0 0.25em; line-height: 1; border-radius: 0.35em; box-decoration-break: clone; -webkit-box-decoration-break: clone"> {text} <span style="font-size: 0.8em; font-weight: bold; line-height: 1; border-radius: 0.35em; text-transform: uppercase; vertical-align: middle; margin-left: 0.1rem">{label}</span></mark>"""
@@ -80,6 +79,7 @@ def fix_floats(in_dict: dict) -> dict:
 
 
 def get_html_and_json(text):
+    cat = get_model_pack()
     doc = cat(text)
 
     a = {