Provide CHECKBOX_RUNTIME environment variable during job execution only (BugFix) (#2362)

* Set CHECKBOX_RUNTIME from within Checkbox when running Snap version

Fix #2295

* Remove CHECKBOX_RUNTIME from wrapper scripts

* Add unit tests for the get_execution_environment function

* black

* Add reference page about environment variables

Author: pieqq

checkbox-core-snap/common_files/config/wrapper_common

@@ -37,10 +37,6 @@ else
   append_path PYTHONPATH $RUNTIME/lib/python3*/dist-packages
 fi
 
-# make sure we always know where the content snap is especially for classic
-# checkbox snaps where the checkbox-runtime bind mount does not exist
-export CHECKBOX_RUNTIME=$(findmnt -oTARGET -n $(findmnt -oSOURCE -n $RUNTIME) | grep -P "^\/snap\/checkbox(|\d{2})\/")
-
 # Tell GStreamer where to find its plugins
 export GST_PLUGIN_PATH=$RUNTIME/usr/lib/$ARCH/gstreamer-1.0
 export GST_PLUGIN_SYSTEM_PATH=$RUNTIME/usr/lib/$ARCH/gstreamer-1.0

checkbox-core-snap/common_files/config/wrapper_common_classic

@@ -45,10 +45,6 @@ else
   append_path PYTHONPATH $RUNTIME/lib/python3*/dist-packages
 fi
 
-# make sure we always know where the content snap is especially for classic
-# checkbox snaps where the checkbox-runtime bind mount does not exist
-export CHECKBOX_RUNTIME=$RUNTIME
-
 # Use a modules directory which doesn't exist so we don't load random things
 # which may then get deleted (or their dependencies) and potentially segfault
 export GIO_MODULE_DIR=$SNAP/gio/modules-dummy

checkbox-ng/plainbox/impl/execution.py

@@ -626,6 +626,8 @@ def set_if_not_none(envvar, source):
     set_if_not_none("PLAINBOX_PROVIDER_DATA", job.provider.data_dir)
     set_if_not_none("PLAINBOX_PROVIDER_UNITS", job.provider.units_dir)
     set_if_not_none("CHECKBOX_SHARE", job.provider.CHECKBOX_SHARE)
+    if os.getenv("SNAP"):
+        set_if_not_none("CHECKBOX_RUNTIME", str(get_checkbox_runtime_path()))
     # Inject additional variables that are requested in the config
     if environ is not None:
         for env_var in environ:

checkbox-ng/plainbox/impl/test_execution.py

@@ -16,8 +16,8 @@
 # You should have received a copy of the GNU General Public License
 # along with Checkbox.  If not, see <http://www.gnu.org/licenses/>.
 
-import os
 import contextlib
+import os
 from pathlib import Path
 from unittest import TestCase, mock
 
@@ -28,6 +28,7 @@
     dangerous_nsenter,
     get_execution_command_subshell,
     get_execution_command_systemd_unit,
+    get_execution_environment,
 )
 from plainbox.impl.unit.job import InvalidJob
 
@@ -459,3 +460,63 @@ def test_present(self):
         self.assertIn("og_path2", new_path)
         self.assertIn("some", new_path)
         self.assertIn("path", new_path)
+
+
+class TestGetExecutionEnvironment(TestCase):
+    def setUp(self):
+        self.job = mock.Mock()
+        self.job.get_flag_set.return_value = set()
+        self.job.provider.gettext_domain = None
+        self.job.provider.locale_dir = None
+        self.job.provider.extra_PYTHONPATH = []
+        self.job.provider.extra_PATH = []
+        self.job.provider.extra_LD_LIBRARY_PATH = []
+        self.job.provider.extra_snap_environment = {}
+        self.job.provider.data_dir = None
+        self.job.provider.units_dir = None
+        self.job.provider.CHECKBOX_SHARE = None
+
+    @mock.patch.dict(os.environ, {"ORIGINAL_ENV": "value"}, clear=True)
+    @mock.patch("plainbox.impl.execution.WellKnownDirsHelper")
+    def test_basic_environment(self, mock_well_known):
+        mock_well_known.session_share.return_value = "/session/share"
+
+        env = get_execution_environment(
+            self.job, None, "test_session", "/nest"
+        )
+
+        self.assertIn("ORIGINAL_ENV", env)
+        self.assertEqual(env["ORIGINAL_ENV"], "value")
+        self.assertEqual(env["PLAINBOX_SESSION_SHARE"], "/session/share")
+        self.assertIn("/nest", env["PATH"])
+        mock_well_known.session_share.assert_called_once_with("test_session")
+
+    @mock.patch.dict(os.environ, {"SNAP": "/snap/checkbox24"}, clear=True)
+    @mock.patch("plainbox.impl.execution.get_checkbox_runtime_path")
+    @mock.patch("plainbox.impl.execution.WellKnownDirsHelper")
+    def test_checkbox_runtime_in_snap(
+        self, mock_well_known, mock_runtime_path
+    ):
+        mock_well_known.session_share.return_value = "/session/share"
+        mock_runtime_path.return_value = Path("/snap/checkbox24/current")
+
+        env = get_execution_environment(
+            self.job, None, "test_session", "/nest"
+        )
+
+        self.assertEqual(env["CHECKBOX_RUNTIME"], "/snap/checkbox24/current")
+
+    @mock.patch.dict(
+        os.environ, {"EXISTING_VAR": "original_value"}, clear=True
+    )
+    @mock.patch("plainbox.impl.execution.WellKnownDirsHelper")
+    def test_environ_dict_does_not_override_existing(self, mock_well_known):
+        mock_well_known.session_share.return_value = "/session/share"
+
+        environ = {"EXISTING_VAR": "new_value"}
+
+        env = get_execution_environment(
+            self.job, environ, "test_session", "/nest"
+        )
+
+        self.assertEqual(env["EXISTING_VAR"], "original_value")

checkbox-ng/plainbox/impl/unit/unit.py

@@ -96,7 +96,6 @@ def get_checkbox_runtime_path():
     #       runtime, while SNAP on the legacy arch is the frontend
     snap_base_n = get_snap_base().replace("core", "")
     # the bases of the runtime and frontend must always match
-    runtime_name = "checkbox" + snap_base_n
     return Path("/snap") / ("checkbox" + snap_base_n) / "current"
 
 

docs/reference/envvar.rst

@@ -0,0 +1,28 @@
+.. _envvar:
+
+Environment variables set by Checkbox
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Checkbox sets a few environment variables during execution. These can be
+used in the job definition itself or even in the script called by the
+``command`` field of a the job.
+
+``PLAINBOX_SESSION_SHARE``
+    Path to a directory that can be used to store temporary data during the
+    test run. This is useful if you have one test gathering data, and another
+    one checking said data. For example, the first test would write its
+    output to ``$PLAINBOX_SESSION_SHARE/my_test_output``, and the other one
+    would retrieve the content of the file to analyze it.
+
+``PLAINBOX_PROVIDER_DATA``
+    Directory within the provider that contains additional data required by
+    some jobs. For instance, the `Base provider data directory`_ contains
+    files used to assign the GPIO pins specific to some hardware.
+
+``CHECKBOX_RUNTIME``
+    Directory where the Checkbox runtime is located. This is especially useful
+    when in a snap environment where test authors may need to point to specific
+    files within the runtime environment. For example, when using the
+    checkbox24 snap, the runtime is ``/snap/checkbox24/current``.
+
+.. _Base provider data directory: https://github.com/canonical/checkbox/tree/main/providers/base/data

docs/reference/index.rst

@@ -8,6 +8,7 @@ Reference
    glossary
    stack
    launcher
+   envvar
    units/index
    snaps
    submission-schema