Add config CLI argument to lint, fix, and parse (#1986)

* Add extra-config CLI argument to lint, fix, and parse

* rename --extra-config to --config

* Fix missing unit test

src/sqlfluff/cli/commands.py

@@ -177,7 +177,6 @@ def core_options(f: Callable) -> Callable:
     f = click.option(
         "--rules",
         default=None,
-        # short_help='Specify a particular rule, or comma separated rules, to check',
         help=(
             "Narrow the search to only specific rules. For example "
             "specifying `--rules L001` will only search for rule `L001` (Unnecessary "
@@ -189,7 +188,6 @@ def core_options(f: Callable) -> Callable:
     f = click.option(
         "--exclude-rules",
         default=None,
-        # short_help='Specify a particular rule, or comma separated rules to exclude',
         help=(
             "Exclude specific rules. For example "
             "specifying `--exclude-rules L001` will remove rule `L001` (Unnecessary "
@@ -200,6 +198,17 @@ def core_options(f: Callable) -> Callable:
             "`L001` and rule `L002`."
         ),
     )(f)
+    f = click.option(
+        "--config",
+        "extra_config_path",
+        default=None,
+        help=(
+            "Include additional config file. By default the config is generated "
+            "from the standard configuration files described in the documentation. This "
+            "argument allows you to specify an additional configuration file that overrides "
+            "the standard configuration files. N.B. cfg format is required."
+        ),
+    )(f)
     f = click.option(
         "--ignore",
         default=None,
@@ -225,7 +234,7 @@ def core_options(f: Callable) -> Callable:
     return f
 
 
-def get_config(**kwargs) -> FluffConfig:
+def get_config(extra_config_path: Optional[str] = None, **kwargs) -> FluffConfig:
     """Get a config object from kwargs."""
     if "dialect" in kwargs:
         try:
@@ -249,7 +258,10 @@ def get_config(**kwargs) -> FluffConfig:
     # Instantiate a config object (filtering out the nulls)
     overrides = {k: kwargs[k] for k in kwargs if kwargs[k] is not None}
     try:
-        return FluffConfig.from_root(overrides=overrides)
+        return FluffConfig.from_root(
+            extra_config_path=extra_config_path,
+            overrides=overrides,
+        )
     except SQLFluffUserError as err:  # pragma: no cover
         click.echo(
             colorize(
@@ -396,6 +408,7 @@ def lint(
     logger: Optional[logging.Logger] = None,
     bench: bool = False,
     disable_progress_bar: Optional[bool] = False,
+    extra_config_path: Optional[str] = None,
     **kwargs,
 ) -> NoReturn:
     """Lint SQL files via passing a list of files or using stdin.
@@ -416,7 +429,7 @@ def lint(
         echo 'select col from tbl' | sqlfluff lint -
 
     """
-    config = get_config(**kwargs)
+    config = get_config(extra_config_path, **kwargs)
     non_human_output = format != FormatType.human.value
     lnt, formatter = get_linter_and_formatter(config, silent=non_human_output)
 
@@ -548,6 +561,7 @@ def fix(
     fixed_suffix: str = "",
     logger: Optional[logging.Logger] = None,
     disable_progress_bar: Optional[bool] = False,
+    extra_config_path: Optional[str] = None,
     **kwargs,
 ) -> NoReturn:
     """Fix SQL files.
@@ -560,7 +574,7 @@ def fix(
     # some quick checks
     fixing_stdin = ("-",) == paths
 
-    config = get_config(**kwargs)
+    config = get_config(extra_config_path, **kwargs)
     lnt, formatter = get_linter_and_formatter(config, silent=fixing_stdin)
 
     verbose = config.get("verbose")
@@ -767,6 +781,7 @@ def parse(
     bench: bool,
     nofail: bool,
     logger: Optional[logging.Logger] = None,
+    extra_config_path: Optional[str] = None,
     **kwargs,
 ) -> NoReturn:
     """Parse SQL files and just spit out the result.
@@ -776,7 +791,7 @@ def parse(
     character to indicate reading from *stdin* or a dot/blank ('.'/' ') which will
     be interpreted like passing the current working directory as a path argument.
     """
-    c = get_config(**kwargs)
+    c = get_config(extra_config_path, **kwargs)
     # We don't want anything else to be logged if we want json or yaml output
     non_human_output = format in (FormatType.json.value, FormatType.yaml.value)
     lnt, formatter = get_linter_and_formatter(c, silent=non_human_output)

src/sqlfluff/core/config.py

@@ -298,6 +298,25 @@ def load_config_at_path(self, path: str) -> dict:
         self._config_cache[str(path)] = configs
         return configs
 
+    def load_extra_config(self, extra_config_path: str) -> dict:
+        """Load specified extra config."""
+        if not os.path.exists(extra_config_path):
+            raise SQLFluffUserError(
+                f"Extra config '{extra_config_path}' does not exist."
+            )
+
+        # First check the cache
+        if str(extra_config_path) in self._config_cache:
+            return self._config_cache[str(extra_config_path)]
+
+        configs: dict = {}
+        elems = self._get_config_elems_from_file(extra_config_path)
+        configs = self._incorporate_vals(configs, elems)
+
+        # Store in the cache
+        self._config_cache[str(extra_config_path)] = configs
+        return configs
+
     @staticmethod
     def _get_user_config_dir_path() -> str:
         appname = "sqlfluff"
@@ -329,13 +348,20 @@ def load_user_config(self) -> dict:
         user_home_path = os.path.expanduser("~")
         return self.load_config_at_path(user_home_path)
 
-    def load_config_up_to_path(self, path: str) -> dict:
+    def load_config_up_to_path(
+        self, path: str, extra_config_path: Optional[str] = None
+    ) -> dict:
         """Loads a selection of config files from both the path and its parent paths."""
         user_appdir_config = self.load_user_appdir_config()
         user_config = self.load_user_config()
         config_paths = self.iter_config_locations_up_to_path(path)
         config_stack = [self.load_config_at_path(p) for p in config_paths]
-        return nested_combine(user_appdir_config, user_config, *config_stack)
+        extra_config = (
+            self.load_extra_config(extra_config_path) if extra_config_path else {}
+        )
+        return nested_combine(
+            user_appdir_config, user_config, *config_stack, extra_config
+        )
 
     @classmethod
     def find_ignore_config_files(
@@ -395,9 +421,13 @@ class FluffConfig:
     def __init__(
         self,
         configs: Optional[dict] = None,
+        extra_config_path: Optional[str] = None,
         overrides: Optional[dict] = None,
         plugin_manager: Optional[pluggy.PluginManager] = None,
     ):
+        self._extra_config_path = (
+            extra_config_path  # We only store this for child configs
+        )
         self._overrides = overrides  # We only store this for child configs
 
         # Fetch a fresh plugin manager if we weren't provided with one
@@ -472,23 +502,33 @@ def __setstate__(self, state):
         # in the child processes.
 
     @classmethod
-    def from_root(cls, overrides: Optional[dict] = None) -> "FluffConfig":
+    def from_root(
+        cls, extra_config_path: Optional[str] = None, overrides: Optional[dict] = None
+    ) -> "FluffConfig":
         """Loads a config object just based on the root directory."""
         loader = ConfigLoader.get_global()
-        c = loader.load_config_up_to_path(path=".")
-        return cls(configs=c, overrides=overrides)
+        c = loader.load_config_up_to_path(path=".", extra_config_path=extra_config_path)
+        return cls(configs=c, extra_config_path=extra_config_path, overrides=overrides)
 
     @classmethod
     def from_path(
         cls,
         path: str,
+        extra_config_path: Optional[str] = None,
         overrides: Optional[dict] = None,
         plugin_manager: Optional[pluggy.PluginManager] = None,
     ) -> "FluffConfig":
         """Loads a config object given a particular path."""
         loader = ConfigLoader.get_global()
-        c = loader.load_config_up_to_path(path=path)
-        return cls(configs=c, overrides=overrides, plugin_manager=plugin_manager)
+        c = loader.load_config_up_to_path(
+            path=path, extra_config_path=extra_config_path
+        )
+        return cls(
+            configs=c,
+            extra_config_path=extra_config_path,
+            overrides=overrides,
+            plugin_manager=plugin_manager,
+        )
 
     @classmethod
     def from_kwargs(
@@ -548,9 +588,12 @@ def get_templater(self, templater_name="jinja", **kwargs):
             )
 
     def make_child_from_path(self, path: str) -> "FluffConfig":
-        """Make a new child config at a path but pass on overrides."""
+        """Make a new child config at a path but pass on overrides and extra_config_path."""
         return self.from_path(
-            path, overrides=self._overrides, plugin_manager=self._plugin_manager
+            path,
+            extra_config_path=self._extra_config_path,
+            overrides=self._overrides,
+            plugin_manager=self._plugin_manager,
         )
 
     def diff_to(self, other: "FluffConfig") -> dict:

src/sqlfluff/core/linter/linter.py

@@ -102,7 +102,9 @@ def rule_tuples(self) -> List[RuleTuple]:
     # These are the building blocks of the linting process.
 
     @staticmethod
-    def _load_raw_file_and_config(fname, root_config):
+    def _load_raw_file_and_config(
+        fname: str, root_config: FluffConfig
+    ) -> Tuple[str, FluffConfig, str]:
         """Load a raw file and the associated config."""
         file_config = root_config.make_child_from_path(fname)
         encoding = get_encoding(fname=fname, config=file_config)

test/cli/commands_test.py

@@ -112,6 +112,25 @@ def test__cli__command_dialect_legacy():
     assert "Please use the 'exasol' dialect instead." in result.stdout
 
 
+def test__cli__command_extra_config_fail():
+    """Check the script raises the right exception on a non-existant extra config path."""
+    result = invoke_assert_code(
+        ret_code=66,
+        args=[
+            lint,
+            [
+                "--config",
+                "test/fixtures/cli/extra_configs/.sqlfluffsdfdfdfsfd",
+                "test/fixtures/cli/extra_config_tsql.sql",
+            ],
+        ],
+    )
+    assert (
+        "Extra config 'test/fixtures/cli/extra_configs/.sqlfluffsdfdfdfsfd' does not exist."
+        in result.stdout
+    )
+
+
 @pytest.mark.parametrize(
     "command",
     [
@@ -263,6 +282,15 @@ def test__cli__command_lint_stdin(command):
         ),
         # Check nofail works
         (lint, ["--nofail", "test/fixtures/linter/parse_lex_error.sql"]),
+        # Check config works (sets dialect to tsql)
+        (
+            lint,
+            [
+                "--config",
+                "test/fixtures/cli/extra_configs/.sqlfluff",
+                "test/fixtures/cli/extra_config_tsql.sql",
+            ],
+        ),
     ],
 )
 def test__cli__command_lint_parse(command):

test/fixtures/cli/extra_config_tsql.sql

@@ -0,0 +1,4 @@
+-- Some tsql specifc sql to test config cli argument.
+BEGIN
+    SELECT 'Weekend';
+END

test/fixtures/cli/extra_configs/.sqlfluff

@@ -0,0 +1,2 @@
+[sqlfluff]
+dialect = tsql