Merge pull request #2471 from lonvia/update-install-rules

[nominatim.git] / nominatim / config.py

diff --git a/nominatim/config.py b/nominatim/config.py
index a8436440b9f5ca78670ba9fe9e1cc8e3979ece96..f316280bb42bf1dfc71bb5b1e16704bbdfcafa5c 100644 (file)
--- a/nominatim/config.py
+++ b/nominatim/config.py
@@ -4,6 +4,7 @@ Nominatim configuration accessor.
 import logging
 import os
 from pathlib import Path
+import yaml
 
 from dotenv import dotenv_values
 
@@ -11,6 +12,27 @@ from nominatim.errors import UsageError
 
 LOG = logging.getLogger()
 
+
+def flatten_config_list(content, section=''):
+    """ Flatten YAML configuration lists that contain include sections
+        which are lists themselves.
+    """
+    if not content:
+        return []
+
+    if not isinstance(content, list):
+        raise UsageError(f"List expected in section '{section}'.")
+
+    output = []
+    for ele in content:
+        if isinstance(ele, list):
+            output.extend(flatten_config_list(ele, section))
+        else:
+            output.append(ele)
+
+    return output
+
+
 class Configuration:
     """ Load and manage the project configuration.
 
@@ -53,7 +75,10 @@ class Configuration:
     def __getattr__(self, name):
         name = 'NOMINATIM_' + name
 
-        return self.environ.get(name) or self._config[name]
+        if name in self.environ:
+            return self.environ[name]
+
+        return self._config[name]
 
     def get_bool(self, name):
         """ Return the given configuration parameter as a boolean.
@@ -114,3 +139,93 @@ class Configuration:
         env.update(self.environ)
 
         return env
+
+
+    def load_sub_configuration(self, filename, config=None):
+        """ Load additional configuration from a file. `filename` is the name
+            of the configuration file. The file is first searched in the
+            project directory and then in the global settings dirctory.
+
+            If `config` is set, then the name of the configuration file can
+            be additionally given through a .env configuration option. When
+            the option is set, then the file will be exclusively loaded as set:
+            if the name is an absolute path, the file name is taken as is,
+            if the name is relative, it is taken to be relative to the
+            project directory.
+
+            The format of the file is determined from the filename suffix.
+            Currently only files with extension '.yaml' are supported.
+
+            YAML files support a special '!include' construct. When the
+            directive is given, the value is taken to be a filename, the file
+            is loaded using this function and added at the position in the
+            configuration tree.
+        """
+        assert Path(filename).suffix == '.yaml'
+
+        configfile = self._find_config_file(filename, config)
+
+        return self._load_from_yaml(configfile)
+
+
+    def _find_config_file(self, filename, config=None):
+        """ Resolve the location of a configuration file given a filename and
+            an optional configuration option with the file name.
+            Raises a UsageError when the file cannot be found or is not
+            a regular file.
+        """
+        if config is not None:
+            cfg_filename = self.__getattr__(config)
+            if cfg_filename:
+                cfg_filename = Path(cfg_filename)
+
+                if cfg_filename.is_absolute():
+                    cfg_filename = cfg_filename.resolve()
+
+                    if not cfg_filename.is_file():
+                        LOG.fatal("Cannot find config file '%s'.", cfg_filename)
+                        raise UsageError("Config file not found.")
+
+                    return cfg_filename
+
+                filename = cfg_filename
+
+
+        search_paths = [self.project_dir, self.config_dir]
+        for path in search_paths:
+            if path is not None and (path / filename).is_file():
+                return path / filename
+
+        LOG.fatal("Configuration file '%s' not found.\nDirectories searched: %s",
+                  filename, search_paths)
+        raise UsageError("Config file not found.")
+
+
+    def _load_from_yaml(self, cfgfile):
+        """ Load a YAML configuration file. This installs a special handler that
+            allows to include other YAML files using the '!include' operator.
+        """
+        yaml.add_constructor('!include', self._yaml_include_representer,
+                             Loader=yaml.SafeLoader)
+        return yaml.safe_load(cfgfile.read_text(encoding='utf-8'))
+
+
+    def _yaml_include_representer(self, loader, node):
+        """ Handler for the '!include' operator in YAML files.
+
+            When the filename is relative, then the file is first searched in the
+            project directory and then in the global settings dirctory.
+        """
+        fname = loader.construct_scalar(node)
+
+        if Path(fname).is_absolute():
+            configfile = Path(fname)
+        else:
+            configfile = self._find_config_file(loader.construct_scalar(node))
+
+        if configfile.suffix != '.yaml':
+            LOG.fatal("Format error while reading '%s': only YAML format supported.",
+                      configfile)
+            raise UsageError("Cannot handle config file format.")
+
+        return yaml.safe_load(configfile.read_text(encoding='utf-8'))