feat: handle retries when fetching from remote registry (#147)

example/entrypoint.sh

@@ -1,10 +1,27 @@
 #!/bin/bash
 . /.venv/bin/activate
 
+MAX_RETRY=10
+REMOTE_DATA_LOCATION="https://registry.spid.gov.it/entities-idp -O ./spid-entities-idps.xml"
+
 # get IDEM MDQ key
 if [[ $GET_IDEM_MDQ_KEY == true ]]; then
   wget https://mdx.idem.garr.it/idem-mdx-service-crt.pem -O $SATOSA_KEYS_FOLDER/idem-mdx-service-crt.pem
-  wget https://registry.spid.gov.it/entities-idp -O metadata/idp/spid-entities-idps.xml
+
+  wget $REMOTE_DATA_LOCATION
+  status=$?
+  while [[ $status != 0 && $MAX_RETRY -gt 0 ]]; do
+    echo "Retrying download from registry.spid.gov.it..."
+    wget $REMOTE_DATA_LOCATION
+    status=$?
+    MAX_RETRY=$((MAX_RETRY-1))
+  done
+
+  if [ $MAX_RETRY == 0 ]; then
+    echo "Cannot fetch identity providers data from remote registry, aborting..."
+    exit 1
+  fi
+
   echo "Downloaded IDEM MDQ key"
 fi