Document dependency conflicts between dbt and Airflow (astronomer#347)

Add a matrix of Apache Airflow versions versus dbt versions,
highlighting which combinations lead to conflict errors.
Document how to re-run the analysis.

docs/dbt/execution-mode-local-conflicts.rst

@@ -0,0 +1,70 @@
+.. _execution-mode-local-conflicts:
+
+Airflow and DBT dependencies conflicts
+======================================
+
+When using the `Local Execution Mode <execution-modes.html#local>`__, users may face dependency conflicts between
+Apache Airflow and DBT. The amount of conflicts may increase depending on the Airflow providers and DBT plugins being used.
+
+If you find errors, we recommend users look into using `alternative execution modes <execution-modes.html>`__.
+
+In the following table, ``x`` represents combinations that lead to conflicts (vanilla ``apache-airflow`` and ``dbt-core`` packages):
+
++---------------+-----+-----+-----+-----+-----+-----+---------+
+| Airflow \ DBT | 1.0 | 1.1 | 1.2 | 1.3 | 1.4 | 1.5 | 1.6.0b6 |
++===============+=====+=====+=====+=====+=====+=====+=========+
+| 2.2           |     |     |     | x   | x   | x   | x       |
++---------------+-----+-----+-----+-----+-----+-----+---------+
+| 2.3           | x   | x   |     | x   | x   | x   | x       |
++---------------+-----+-----+-----+-----+-----+-----+---------+
+| 2.4           | x   | x   | x   |     |     |     |         |
++---------------+-----+-----+-----+-----+-----+-----+---------+
+| 2.5           | x   | x   | x   |     |     |     |         |
++---------------+-----+-----+-----+-----+-----+-----+---------+
+| 2.6           | x   | x   | x   | x   | x   |     | x       |
++---------------+-----+-----+-----+-----+-----+-----+---------+
+
+Examples of errors
+-----------------------------------
+
+.. code-block:: bash
+
+  ERROR: Cannot install apache-airflow==2.2.4 and dbt-core==1.5.0 because these package versions have conflicting dependencies.
+  The conflict is caused by:
+    apache-airflow 2.2.4 depends on jinja2<3.1 and >=2.10.1
+    dbt-core 1.5.0 depends on Jinja2==3.1.2
+
+.. code-block:: bash
+
+  ERROR: Cannot install apache-airflow==2.6.0 and dbt-core because these package versions have conflicting dependencies.
+  The conflict is caused by:
+    apache-airflow 2.6.0 depends on importlib-metadata<5.0.0 and >=1.7; python_version < "3.9"
+    dbt-semantic-interfaces 0.1.0.dev7 depends on importlib-metadata==6.6.0
+
+
+How to reproduce
+----------------
+
+The table was created by running  `nox <https://nox.thea.codes/en/stable/>`__ with the following ``noxfile.py``:
+
+.. code-block:: python
+
+  import nox
+
+
+  nox.options.sessions = ["compatibility"]
+  nox.options.reuse_existing_virtualenvs = True
+
+
+  @nox.session(python=["3.10"])
+  @nox.parametrize("dbt_version", ["1.0", "1.1", "1.2", "1.3", "1.4", "1.5", "1.6.0b6"])
+  @nox.parametrize("airflow_version", ["2.2.4", "2.3", "2.4", "2.5", "2.6"])
+  def compatibility(session: nox.Session, airflow_version, dbt_version) -> None:
+      """Run both unit and integration tests."""
+      session.run(
+          "pip3",
+          "install",
+          "--pre",
+          f"apache-airflow=={airflow_version}",
+          f"dbt-core=={dbt_version}",
+      )

docs/dbt/execution-modes.rst

@@ -46,7 +46,7 @@ Local
 By default, Cosmos uses the ``local`` execution mode.
 
 The ``local`` execution mode is the fastest way to run Cosmos operators since they don't install ``dbt`` nor build docker containers. However, it may not be an option for users using managed Airflow services such as
-Google Cloud Composer, since Airflow and ``dbt`` dependencies can conflict, the user may not be able to install ``dbt`` in a custom path.
+Google Cloud Composer, since Airflow and ``dbt`` dependencies can `conflict <execution-mode-local-conflicts.html>`__, the user may not be able to install ``dbt`` in a custom path.
 
 The ``local`` execution mode assumes a ``dbt`` binary is reachable within the Airflow worker node.