Build: show the YAML config file before validating it (#11175)

* Build: show the YAML config file before validating it

This moves the `cat readthedocs.yaml` command _before_ validating the YAML file.
This allows the user to inspect the configuration file in case it fails due to a
validation error.

Closes #11097

* Use a better name for the variable

* Omit check for `cat readthedocs.yaml` for now

We can't perform this check on the "build environment" because it happens in the
"VCS environment" now and we are not mocking it.

We should find a way to check these commands on the "VCS environment".

Author: humitos

readthedocs/doc_builder/director.py

@@ -16,6 +16,8 @@
 from django.utils.translation import gettext_lazy as _
 
 from readthedocs.builds.constants import EXTERNAL
+from readthedocs.config.config import CONFIG_FILENAME_REGEX
+from readthedocs.config.find import find_one
 from readthedocs.core.utils.filesystem import safe_open
 from readthedocs.doc_builder.config import load_yaml_config
 from readthedocs.doc_builder.exceptions import BuildUserError
@@ -108,20 +110,6 @@ def setup_vcs(self):
         # self.run_build_job("pre_checkout")
         self.checkout()
 
-        # Output the path for the config file used.
-        # This works as confirmation for us & the user about which file is used,
-        # as well as the fact that *any* config file is used.
-        if self.data.config.source_file:
-            cwd = self.data.project.checkout_path(self.data.version.slug)
-            command = self.vcs_environment.run(
-                "cat",
-                # Show user the relative path to the config file
-                # TODO: Have our standard path replacement code catch this.
-                # https://github.com/readthedocs/readthedocs.org/pull/10413#discussion_r1230765843
-                self.data.config.source_file.replace(cwd + "/", ""),
-                cwd=cwd,
-            )
-
         self.run_build_job("post_checkout")
 
         commit = self.data.build_commit or self.vcs_repository.commit
@@ -240,6 +228,24 @@ def checkout(self):
 
         if custom_config_file:
             log.info("Using a custom .readthedocs.yaml file.", path=custom_config_file)
+
+        checkout_path = self.data.project.checkout_path(self.data.version.slug)
+        default_config_file = find_one(checkout_path, CONFIG_FILENAME_REGEX)
+        final_config_file = custom_config_file or default_config_file
+
+        # Output the path for the config file used.
+        # This works as confirmation for us & the user about which file is used,
+        # as well as the fact that *any* config file is used.
+        if final_config_file:
+            command = self.vcs_environment.run(
+                "cat",
+                # Show user the relative path to the config file
+                # TODO: Have our standard path replacement code catch this.
+                # https://github.com/readthedocs/readthedocs.org/pull/10413#discussion_r1230765843
+                final_config_file.replace(checkout_path + "/", ""),
+                cwd=checkout_path,
+            )
+
         self.data.config = load_yaml_config(
             version=self.data.version,
             readthedocs_yaml_path=custom_config_file,

readthedocs/projects/tests/test_build_tasks.py

@@ -810,11 +810,14 @@ def test_build_commands_executed(
         python_version = settings.RTD_DOCKER_BUILD_SETTINGS["tools"]["python"]["3"]
         self.mocker.mocks["environment.run"].assert_has_calls(
             [
-                mock.call(
-                    "cat",
-                    "readthedocs.yml",
-                    cwd="/tmp/readthedocs-tests/git-repository",
-                ),
+                # TODO: check for this in the VCS environment.
+                # We can't check it here because this is the build environment.
+                #
+                # mock.call(
+                #     "cat",
+                #     "readthedocs.yml",
+                #     cwd="/tmp/readthedocs-tests/git-repository",
+                # ),
                 mock.call("asdf", "install", "python", python_version),
                 mock.call("asdf", "global", "python", python_version),
                 mock.call("asdf", "reshim", "python", record=False),
@@ -1348,7 +1351,10 @@ def test_conda_config_calls_conda_command(self, load_yaml_config):
         ]
         self.mocker.mocks["environment.run"].assert_has_calls(
             [
-                mock.call("cat", "readthedocs.yml", cwd=mock.ANY),
+                # TODO: check for this in the VCS environment.
+                # We can't check it here because this is the build environment.
+                #
+                # mock.call("cat", "readthedocs.yml", cwd=mock.ANY),
                 mock.call("asdf", "install", "python", python_version),
                 mock.call("asdf", "global", "python", python_version),
                 mock.call("asdf", "reshim", "python", record=False),
@@ -1442,7 +1448,10 @@ def test_python_mamba_commands(self, load_yaml_config):
 
         self.mocker.mocks["environment.run"].assert_has_calls(
             [
-                mock.call("cat", "readthedocs.yml", cwd=mock.ANY),
+                # TODO: check for this in the VCS environment.
+                # We can't check it here because this is the build environment.
+                #
+                # mock.call("cat", "readthedocs.yml", cwd=mock.ANY),
                 mock.call("asdf", "install", "python", "mambaforge-4.10.3-10"),
                 mock.call("asdf", "global", "python", "mambaforge-4.10.3-10"),
                 mock.call("asdf", "reshim", "python", record=False),