Add TOML configuration file support

Layout is:

[tool.newrelic]
app_name = "app name"

Keys with . in them are expanded to be subkeys:

[tool.newrelic.browser_monitoring]
enabled = true

Anything that is a list in the layout is made into a string joined with a single space.

import-hook: is translated as such:

[tool.newrelic.import-hook.module_name]
"sub.sub" = ["item1", "item2"]

error_collector.ignore_errors:

[tool.newrelic.error_collector]
ignore_errors = ["module.name:ClassName", "module.name:ClassName2"]

Environment use the tool.newrelic.env namespace:

[tool.newrelic.env.production]
app_name = "production name"

newrelic/config.py

@@ -911,6 +911,32 @@ def apply_local_high_security_mode_setting(settings):
     return settings
 
 
+def _toml_config_to_configparser_dict(d, top=None, _path=None):
+    def is_list_of_str(ls):
+        return isinstance(ls, list) and all(isinstance(item, str) for item in ls)
+
+    top = top or {"newrelic": {}}
+    _path = _path or ""
+    for key, value in d.items():
+        if isinstance(value, dict):
+            _toml_config_to_configparser_dict(value, top, f"{_path}.{key}" if _path else key)
+        else:
+            fixed_value = " ".join(value) if is_list_of_str(value) else value
+            path_split = _path.split(".")
+            # Handle environments
+            if _path.startswith("env."):
+                env_key = f"newrelic:{path_split[1]}"
+                fixed_key = ".".join((*path_split[2:], key))
+                top[env_key] = {**top.get(env_key, {}), fixed_key: fixed_value}
+            # Handle import-hook:... configuration
+            elif _path.startswith("import-hook."):
+                import_hook_key = f"import-hook:{'.'.join(path_split[1:])}"
+                top[import_hook_key] = {**top.get(import_hook_key, {}), key: fixed_value}
+            else:
+                top["newrelic"][f"{_path}.{key}" if _path else key] = fixed_value
+    return top
+
+
 def _load_configuration(
     config_file=None,
     environment=None,
@@ -994,8 +1020,20 @@ def _load_configuration(
 
     # Now read in the configuration file. Cache the config file
     # name in internal settings object as indication of succeeding.
-
-    if not _config_object.read([config_file]):
+    if config_file.endswith(".toml"):
+        try:
+            import tomllib
+        except ImportError:
+            raise newrelic.api.exceptions.ConfigurationError(
+                "TOML configuration file can only be used if tomllib is available (Python 3.11+)."
+            )
+        with open(config_file, "rb") as f:
+            content = tomllib.load(f)
+            newrelic_section = content.get("tool", {}).get("newrelic")
+            if not newrelic_section:
+                raise newrelic.api.exceptions.ConfigurationError("New Relic configuration not found in TOML file.")
+            _config_object.read_dict(_toml_config_to_configparser_dict(newrelic_section))
+    elif not _config_object.read([config_file]):
         raise newrelic.api.exceptions.ConfigurationError(f"Unable to open configuration file {config_file}.")
 
     _settings.config_file = config_file

tests/agent_features/test_configuration.py

@@ -949,6 +949,73 @@ def test_initialize_developer_mode(section, expect_error, logger):
         assert "CONFIGURATION ERROR" not in logger.caplog.records
 
 
+newrelic_toml_contents = b"""
+[tool.newrelic]
+app_name = "test11"
+monitor_mode = true
+
+[[tool.newrelic.url_rules]]
+ignore = false
+match_expression = ".*\\\\.(ace|arj|ini|txt|udl|plist|css|gif|ico|jpe?g|js|png|swf|woff|caf|aiff|m4v|mpe?g|mp3|mp4|mov)$"
+
+[tool.newrelic.env.development]
+app_name = "test11 (Development)"
+
+[tool.newrelic.env.production]
+app_name = "test11 (Production)"
+log_level = "error"
+
+[tool.newrelic.env.production.distributed_tracing]
+enabled = false
+
+[tool.newrelic.error_collector]
+enabled = true
+ignore_errors = ["module:name1", "module:name"]
+
+[tool.newrelic.transaction_tracer]
+enabled = true
+
+[tool.newrelic.import-hook.django]
+"instrumentation.scripts.django_admin" = ["stuff", "stuff2"]
+"""
+
+
+def test_toml_parse_development():
+    settings = global_settings()
+    _reset_configuration_done()
+    _reset_config_parser()
+    _reset_instrumentation_done()
+
+    with tempfile.NamedTemporaryFile(suffix=".toml") as f:
+        f.write(newrelic_toml_contents)
+        f.seek(0)
+
+        initialize(config_file=f.name, environment="development")
+        value = fetch_config_setting(settings, "app_name")
+        assert value != "test11"
+        value = fetch_config_setting(settings, "monitor_mode")
+        assert value is True
+        value = fetch_config_setting(settings, "error_collector")
+        assert value.enabled is True
+        assert value.ignore_classes[0] == "module:name1"
+        assert value.ignore_classes[1] == "module:name"
+
+
+def test_toml_parse_production():
+    settings = global_settings()
+    # _reset_configuration_done()
+
+    with tempfile.NamedTemporaryFile(suffix=".toml") as f:
+        f.write(newrelic_toml_contents)
+        f.seek(0)
+
+        initialize(config_file=f.name, environment="production")
+        value = fetch_config_setting(settings, "app_name")
+        assert value == "test11 (Production)"
+        value = fetch_config_setting(settings, "distributed_tracing")
+        assert value.enabled is False
+
+
 @pytest.fixture
 def caplog_handler():
     class CaplogHandler(logging.StreamHandler):