fix: bind-mount in dev-specific services

The -m/--mount option makes it possible to bind-mount volumes at runtime. The
volumes are declared in a local/docker-compose.tmp.yml file. The problem with
this approach is when we want to bind-mount a volume to a service which is
specific to the dev context. For instance: the "learning" service when the MFE
plugin is enabled.

In such a case, starting the service triggers a call to `docker-compose stop`
in the local context. This call fails because the "learning" service does not
exist in the local context. Note that this issue only seems to occur with
docker-compose v1.

To resolve this issue, we create two additional filters for
the dev context, which emulate the behaviour of the local context. With this approach, we convert the -m/--mount arguments right after they are parsed. Because they are parsed just once, we can get rid of the de-duplication logic initially introduced with the COMPOSE_CLI_MOUNTS context.

Close #711. Close also overhangio/tutor-mfe#57.

CHANGELOG.md

@@ -18,8 +18,9 @@ Every user-facing change should have an entry in this changelog. Please respect
 
 ## Unreleased
 
+- [Bugfix] Fix `tutor dev start -m /path/to/frontend-app-learning` by introducing dev-specific `COMPOSE_DEV_TMP` and `COMPOSE_DEV_JOBS_TMP` filters (by @regisb).
 - [Bugfix] Log the shell commands that Tutor executes more accurately. (by @kdmccormick)
-- [Fix] `tutor dev quickstart` would fail under certain versions of docker-compose due to a bug in the logic that handled volume mounting. (by @kdmccormick)
+- [Bugfix] `tutor dev quickstart` would fail under certain versions of docker-compose due to a bug in the logic that handled volume mounting. (by @kdmccormick)
 - [Bugfix] The `tutor k8s start` command will succeed even when `k8s-override` and `kustomization-patches-strategic-merge` are not specified. (by @edazzocaisser)
 - [Fix] `kubectl wait` checks deployments instead of pods as it could hang indefinitely if there are extra pods in a broken state. (by @keithgg)
 

tests/commands/test_compose.py

@@ -1,5 +1,7 @@
 import typing as t
 import unittest
+from io import StringIO
+from unittest.mock import patch
 
 from click.exceptions import ClickException
 
@@ -42,25 +44,21 @@ def test_mount_option_parsing(self) -> None:
         with self.assertRaises(ClickException):
             param("lms,:/path/to/edx-platform:/openedx/edx-platform")
 
-    def test_compose_local_tmp_generation(self) -> None:
+    @patch("sys.stdout", new_callable=StringIO)
+    def test_compose_local_tmp_generation(self, _mock_stdout: StringIO) -> None:
         """
-        Ensure that docker-compose.tmp.yml is correctly generated, even when
-        mounts are processed more than once.
+        Ensure that docker-compose.tmp.yml is correctly generated.
         """
         param = compose.MountParam()
-        mount_args: t.Tuple[t.List[compose.MountParam.MountType], ...] = (
-            # Auto-mounting of edx-platform to lms* and cms*
-            param("/path/to/edx-platform"),
-            # Manual mounting of some other folder to mfe and lms
-            param("mfe,lms:/path/to/something-else:/openedx/something-else"),
+        mount_args: t.List[compose.MountParam.MountType] = []
+        # Auto-mounting of edx-platform to lms* and cms*
+        mount_args += param.convert_implicit_form("/path/to/edx-platform")
+        # Manual mounting of some other folder to mfe and lms
+        mount_args += param.convert_explicit_form(
+            "mfe,lms:/path/to/something-else:/openedx/something-else"
         )
-
-        # In some cases, process_mount_arguments ends up being called more
-        # than once. To ensure that we can handle that situation, we call it
-        # multiple times here.
-        compose.process_mount_arguments(mount_args)
-        compose.process_mount_arguments(mount_args)
-        compose.process_mount_arguments(mount_args)
+        # Mount volumes
+        compose.mount_tmp_volumes(mount_args, compose.BaseComposeContext(""))
 
         compose_file: t.Dict[str, t.Any] = hooks.Filters.COMPOSE_LOCAL_TMP.apply({})
         actual_services: t.Dict[str, t.Any] = compose_file["services"]