fix(logger): do not output WARN level logs for non-root modules (#3760)

A user has reported issues which actually resulted from a particular
`bazel` version being used and once he updated, the issues disappeared
because of changes in implicit non-root module dependencies.

In order to reduce the warning spam of non-root modules, set the default
level to `ERROR` for non-root module parsing context and `WARN` for root
module context. This means that the users will not get console output
that they have no way to fix without patching upstream dependencies.

At the same time ensure that the name of the module is printed together
with the logs to better understand where something is coming from.

Fixes #3749

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
(cherry picked from commit 5511aaf)

Author: aignas

CHANGELOG.md

@@ -58,6 +58,8 @@ END_UNRELEASED_TEMPLATE
 * (pypi) Fix the versions of packages that we are recording to a `MODULE.bazel.lock` file
   facts by passing all of the versions to the `get_index` function.
   Fixes [#3756](https://github.com/bazel-contrib/rules_python/issues/3756).
+* (bzlmod) Reduce default verbosity of our loggers for non-root modules
+  ([#3749](https://github.com/bazel-contrib/rules_python/issues/3749)).
 
 {#v2-0-0}
 ## [2.0.0] - 2026-04-09

python/private/pypi/extension.bzl

@@ -244,7 +244,7 @@ You cannot use both the additive_build_content and additive_build_content_file a
                     minor_mapping = kwargs.get("minor_mapping", MINOR_MAPPING),
                     evaluate_markers_fn = kwargs.get("evaluate_markers", None),
                     available_interpreters = kwargs.get("available_interpreters", INTERPRETER_LABELS),
-                    logger = repo_utils.logger(module_ctx, "pypi:hub:" + hub_name),
+                    logger = repo_utils.logger(module_ctx, "pypi:hub:" + hub_name, mod = mod),
                 )
                 pip_hub_map[pip_attr.hub_name] = builder
             elif pip_hub_map[hub_name].module_name != mod.name:

python/private/python.bzl

@@ -31,7 +31,7 @@ load(
 )
 load(":version.bzl", "version")
 
-def parse_modules(*, module_ctx, logger, _fail = fail):
+def parse_modules(*, module_ctx, logger = None, _fail = fail):
     """Parse the modules and return a struct for registrations.
 
     Args:
@@ -137,7 +137,7 @@ def parse_modules(*, module_ctx, logger, _fail = fail):
                         first = first,
                         second_toolchain_name = toolchain_name,
                         second_module_name = mod.name,
-                        logger = logger,
+                        logger = logger or repo_utils.logger(module_ctx, "python", mod = mod),
                     )
                 toolchain_info = None
             else:
@@ -213,8 +213,10 @@ def parse_modules(*, module_ctx, logger, _fail = fail):
     )
 
 def _python_impl(module_ctx):
-    logger = repo_utils.logger(module_ctx, "python")
-    py = parse_modules(module_ctx = module_ctx, logger = logger)
+    py = parse_modules(module_ctx = module_ctx)
+
+    # For all other processing (after parsing the modules) let's use a single logger.
+    logger = repo_utils.logger(module_ctx, "python", mod = module_ctx.modules[0])
 
     # Host compatible runtime repos
     # dict[str version, struct] where struct has:

python/private/repo_utils.bzl

@@ -31,7 +31,7 @@ def _is_repo_debug_enabled(mrctx):
     """
     return mrctx.getenv(REPO_DEBUG_ENV_VAR) == "1"
 
-def _logger(mrctx = None, name = None, verbosity_level = None, printer = None):
+def _logger(mrctx = None, name = None, verbosity_level = None, printer = None, mod = None):
     """Creates a logger instance for printing messages.
 
     Args:
@@ -42,6 +42,7 @@ def _logger(mrctx = None, name = None, verbosity_level = None, printer = None):
             taken from `mrctx`.
         printer: a function to use for printing. Defaults to `print` or `fail` depending
             on the logging method.
+        mod: {type}`module_ctx.module`. The module for which the logger is created.
 
     Returns:
         A struct with attributes logging: trace, debug, info, warn, fail.
@@ -50,20 +51,30 @@ def _logger(mrctx = None, name = None, verbosity_level = None, printer = None):
         the logger injected into the function work as expected by terminating
         on the given line.
     """
+    default_verbosity_level = "WARN"
+    if mod:
+        if name:
+            name = "{}:{}".format(mod.name, name)
+        else:
+            name = mod.name
+
+        if not mod.is_root:
+            default_verbosity_level = "ERROR"  # the warnings are non actionable anyway, but we should keep them.
+
     if verbosity_level == None:
         if _is_repo_debug_enabled(mrctx):
-            verbosity_level = "DEBUG"
-        else:
-            verbosity_level = "WARN"
+            default_verbosity_level = "DEBUG"
 
         env_var_verbosity = mrctx.getenv(REPO_VERBOSITY_ENV_VAR)
-        verbosity_level = env_var_verbosity or verbosity_level
+        verbosity_level = env_var_verbosity or default_verbosity_level
 
     verbosity = {
         "DEBUG": 2,
+        "ERROR": -1,
         "FAIL": -1,
         "INFO": 1,
         "TRACE": 3,
+        "WARN": 0,
     }.get(verbosity_level, 0)
 
     if hasattr(mrctx, "attr"):