introduce custom UsageError

This is a exception to be thrown when the error occures because
of bad user data. We don't want to print a full stack trace in
these cases but just tell the user what went wrong.

nominatim/cli.py

@@ -14,6 +14,7 @@ from .config import Configuration
 from .tools.exec_utils import run_legacy_script, run_api_script
 from .db.connection import connect
 from .db import status
+from .errors import UsageError
 
 LOG = logging.getLogger()
 
@@ -89,7 +90,16 @@ class CommandlineParser:
 
         args.config = Configuration(args.project_dir, args.data_dir / 'settings')
 
-        return args.command.run(args)
+        try:
+            return args.command.run(args)
+        except UsageError as e:
+            log = logging.getLogger()
+            if log.isEnabledFor(logging.DEBUG):
+                raise # use Python's exception printing
+            log.fatal('FATAL: ' + str(e))
+
+        # If we get here, then execution has failed in some way.
+        return 1
 
 
 def _osm2pgsql_options_from_args(args, default_cache, default_threads):
@@ -292,12 +302,12 @@ class UpdateReplication:
                       "Please check install documentation "
                       "(https://nominatim.org/release-docs/latest/admin/Import-and-Update#"
                       "setting-up-the-update-process).")
-            raise RuntimeError("Invalid replication update interval setting.")
+            raise UsageError("Invalid replication update interval setting.")
 
         if not args.once:
             if not args.do_index:
                 LOG.fatal("Indexing cannot be disabled when running updates continuously.")
-                raise RuntimeError("Bad arguments.")
+                raise UsageError("Bad argument '--no-index'.")
             recheck_interval = args.config.get_int('REPLICATION_RECHECK_INTERVAL')
 
         while True:

nominatim/config.py

@@ -7,6 +7,8 @@ from pathlib import Path
 
 from dotenv import dotenv_values
 
+from .errors import UsageError
+
 LOG = logging.getLogger()
 
 class Configuration:
@@ -57,7 +59,7 @@ class Configuration:
             return int(self.__getattr__(name))
         except ValueError:
             LOG.fatal("Invalid setting NOMINATIM_%s. Needs to be a number.", name)
-            raise
+            raise UsageError("Configuration error.")
 
 
     def get_libpq_dsn(self):

nominatim/db/connection.py

@@ -27,7 +27,7 @@ class _Cursor(psycopg2.extras.DictCursor):
         self.execute(sql, args)
 
         if self.rowcount != 1:
-            raise ValueError("Query did not return a single row.")
+            raise RuntimeError("Query did not return a single row.")
 
         return self.fetchone()[0]
 

nominatim/db/status.py

@@ -6,6 +6,7 @@ import logging
 import re
 
 from ..tools.exec_utils import get_url
+from ..errors import UsageError
 
 LOG = logging.getLogger()
 
@@ -19,7 +20,7 @@ def compute_database_date(conn):
 
         if osmid is None:
             LOG.fatal("No data found in the database.")
-            raise RuntimeError("No data found in the database.")
+            raise UsageError("No data found in the database.")
 
     LOG.info("Using node id %d for timestamp lookup", osmid)
     # Get the node from the API to find the timestamp when it was created.
@@ -31,7 +32,7 @@ def compute_database_date(conn):
     if match is None:
         LOG.fatal("The node data downloaded from the API does not contain valid data.\n"
                   "URL used: %s", node_url)
-        raise RuntimeError("Bad API data.")
+        raise UsageError("Bad API data.")
 
     LOG.debug("Found timestamp %s", match[1])
 

nominatim/errors.py

@@ -0,0 +1,9 @@
+"""
+Custom exception and error classes for Nominatim.
+"""
+
+class UsageError(Exception):
+    """ An error raised because of bad user input. This error will usually
+        not cause a stack trace to be printed unless debugging is enabled.
+    """
+    pass

nominatim/tools/replication.py

@@ -11,6 +11,7 @@ from osmium import WriteHandler
 
 from ..db import status
 from .exec_utils import run_osm2pgsql
+from ..errors import UsageError
 
 LOG = logging.getLogger()
 
@@ -31,7 +32,7 @@ def init_replication(conn, base_url):
         LOG.fatal("Cannot reach the configured replication service '%s'.\n"
                   "Does the URL point to a directory containing OSM update data?",
                   base_url)
-        raise RuntimeError("Failed to reach replication service")
+        raise UsageError("Failed to reach replication service")
 
     status.set_status(conn, date=date, seq=seq)
 
@@ -80,7 +81,7 @@ def update(conn, options):
     if startseq is None:
         LOG.error("Replication not set up. "
                   "Please run 'nominatim replication --init' first.")
-        raise RuntimeError("Replication not set up.")
+        raise UsageError("Replication not set up.")
 
     if not indexed and options['indexed_only']:
         LOG.info("Skipping update. There is data that needs indexing.")