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

CHANGELOG.md

@@ -115,6 +115,8 @@ 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

@@ -358,7 +358,7 @@ 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"):