Add support to store and fetch dbt ls cache in remote stores

cosmos/__init__.py

@@ -5,7 +5,7 @@
 
 Contains dags, task groups, and operators.
 """
-__version__ = "1.5.1"
+__version__ = "1.6.0a6"
 
 
 from cosmos.airflow.dag import DbtDag

cosmos/cache.py

@@ -17,6 +17,7 @@
 from airflow.models.dag import DAG
 from airflow.utils.session import provide_session
 from airflow.utils.task_group import TaskGroup
+from airflow.version import version as airflow_version
 from sqlalchemy import select
 from sqlalchemy.orm import Session
 
@@ -25,22 +26,66 @@
     DBT_MANIFEST_FILE_NAME,
     DBT_TARGET_DIR_NAME,
     DEFAULT_PROFILES_FILE_NAME,
+    FILE_SCHEME_AIRFLOW_DEFAULT_CONN_ID_MAP,
     PACKAGE_LOCKFILE_YML,
 )
 from cosmos.dbt.project import get_partial_parse_path
+from cosmos.exceptions import CosmosValueError
 from cosmos.log import get_logger
 from cosmos.settings import (
+    AIRFLOW_IO_AVAILABLE,
     cache_dir,
     dbt_profile_cache_dir_name,
     enable_cache,
     enable_cache_package_lockfile,
     enable_cache_profile,
+    remote_cache_dir_conn_id,
 )
+from cosmos.settings import remote_cache_dir as settings_remote_cache_dir
 
 logger = get_logger(__name__)
 VAR_KEY_CACHE_PREFIX = "cosmos_cache__"
 
 
+def _configure_remote_cache_dir() -> Path | None:
+    """Configure the remote cache dir if it is provided."""
+    if not settings_remote_cache_dir:
+        return None
+
+    _configured_cache_dir = None
+
+    cache_dir_str = str(settings_remote_cache_dir)
+
+    remote_cache_conn_id = remote_cache_dir_conn_id
+    if not remote_cache_conn_id:
+        cache_dir_schema = cache_dir_str.split("://")[0]
+        remote_cache_conn_id = FILE_SCHEME_AIRFLOW_DEFAULT_CONN_ID_MAP.get(cache_dir_schema, None)  # type: ignore[assignment]
+    if remote_cache_conn_id is None:
+        return _configured_cache_dir
+
+    if not AIRFLOW_IO_AVAILABLE:
+        raise CosmosValueError(
+            f"You're trying to specify remote cache_dir {cache_dir_str}, but the required "
+            f"Object Storage feature is unavailable in Airflow version {airflow_version}. Please upgrade to "
+            "Airflow 2.8 or later."
+        )
+
+    from airflow.io.path import ObjectStoragePath
+
+    _configured_cache_dir = ObjectStoragePath(cache_dir_str, conn_id=remote_cache_conn_id)
+
+    if not _configured_cache_dir.exists():  # type: ignore[no-untyped-call]
+        # TODO: Check if we should raise an error instead in case the provided path does not exist.
+        _configured_cache_dir.mkdir(parents=True, exist_ok=True)
+
+        # raise CosmosValueError(
+        #     f"remote_cache_path `{cache_dir_str}` does not exist or is not accessible using "
+        #     f"remote_cache_conn_id `{remote_cache_conn_id}`"
+        # )
+
+    return _configured_cache_dir
+
+
 def _get_airflow_metadata(dag: DAG, task_group: TaskGroup | None) -> dict[str, str | None]:
     dag_id = None
     task_group_id = None
@@ -366,6 +411,64 @@
     return deleted_cosmos_variables
 
 
+# TODO: Add integration tests once remote cache is supported in the CI pipeline
+@provide_session
+def delete_unused_dbt_ls_remote_cache_files(  # pragma: no cover
+    max_age_last_usage: timedelta = timedelta(days=30), session: Session | None = None
+) -> int:
+    """
+    Delete Cosmos cache stored in remote storage based on the last execution of their associated DAGs.
+    """
+    if session is None:
+        return 0
+
+    logger.info(f"Delete the Cosmos cache stored remotely that hasn't been used for  {max_age_last_usage}")
+    cosmos_dags_ids_remote_cache_files = defaultdict(list)
+
+    configured_remote_cache_dir = _configure_remote_cache_dir()
+    if not configured_remote_cache_dir:
+        logger.info(
+            "No remote cache directory configured. Skipping the deletion of the dbt ls cache files in remote storage."
+        )
+        return 0
+
+    dirs = [obj for obj in configured_remote_cache_dir.iterdir() if obj.is_dir()]
+    files = [f for label in dirs for f in label.iterdir() if f.is_file()]
+
+    total_cosmos_remote_cache_files = 0
+    for file in files:
+        prefix_path = (configured_remote_cache_dir / VAR_KEY_CACHE_PREFIX).as_uri()
+        if file.as_uri().startswith(prefix_path):
+            with file.open("r") as fp:
+                cache_dict = json.load(fp)
+            cosmos_dags_ids_remote_cache_files[cache_dict["dag_id"]].append(file)
+            total_cosmos_remote_cache_files += 1
+
+    deleted_cosmos_remote_cache_files = 0
+
+    for dag_id, files in cosmos_dags_ids_remote_cache_files.items():
+        last_dag_run = (
+            session.query(DagRun)
+            .filter(
+                DagRun.dag_id == dag_id,
+            )
+            .order_by(DagRun.execution_date.desc())
+            .first()
+        )
+        if last_dag_run and last_dag_run.execution_date < (datetime.now(timezone.utc) - max_age_last_usage):
+            for file in files:
+                logger.info(f"Removing the dbt ls cache remote file {file}")
+                file.unlink()
+                deleted_cosmos_remote_cache_files += 1
+    logger.info(
+        "Deleted %s/%s dbt ls cache files in remote storage.",
+        deleted_cosmos_remote_cache_files,
+        total_cosmos_remote_cache_files,
+    )
+
+    return deleted_cosmos_remote_cache_files
+
+
 def is_profile_cache_enabled() -> bool:
     """Return True if global and profile cache is enable"""
     return enable_cache and enable_cache_profile

cosmos/dbt/graph.py

@@ -19,6 +19,7 @@
 
 from cosmos import cache, settings
 from cosmos.cache import (
+    _configure_remote_cache_dir,
     _copy_cached_package_lockfile_to_project,
     _get_latest_cached_package_lockfile,
     is_cache_package_lockfile_enabled,
@@ -312,7 +313,22 @@ def save_dbt_ls_cache(self, dbt_ls_output: str) -> None:
             "last_modified": datetime.datetime.now(datetime.timezone.utc).isoformat(),
             **self.airflow_metadata,
         }
-        Variable.set(self.dbt_ls_cache_key, cache_dict, serialize_json=True)
+        remote_cache_dir = _configure_remote_cache_dir()
+        if remote_cache_dir:
+            remote_cache_key_path = remote_cache_dir / self.dbt_ls_cache_key / "dbt_ls_cache.json"
+            with remote_cache_key_path.open("w") as fp:
+                json.dump(cache_dict, fp)
+        else:
+            Variable.set(self.dbt_ls_cache_key, cache_dict, serialize_json=True)
+
+    def _get_dbt_ls_remote_cache(self, remote_cache_dir: Path) -> dict[str, str]:
+        """Loads the remote cache for dbt ls."""
+        cache_dict: dict[str, str] = {}
+        remote_cache_key_path = remote_cache_dir / self.dbt_ls_cache_key / "dbt_ls_cache.json"
+        if remote_cache_key_path.exists():
+            with remote_cache_key_path.open("r") as fp:
+                cache_dict = json.load(fp)
+        return cache_dict
 
     def get_dbt_ls_cache(self) -> dict[str, str]:
         """
@@ -327,7 +343,12 @@ def get_dbt_ls_cache(self) -> dict[str, str]:
         """
         cache_dict: dict[str, str] = {}
         try:
-            cache_dict = Variable.get(self.dbt_ls_cache_key, deserialize_json=True)
+            remote_cache_dir = _configure_remote_cache_dir()
+            cache_dict = (
+                self._get_dbt_ls_remote_cache(remote_cache_dir)
+                if remote_cache_dir
+                else Variable.get(self.dbt_ls_cache_key, deserialize_json=True)
+            )
         except (json.decoder.JSONDecodeError, KeyError):
             return cache_dict
         else:

cosmos/settings.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import os
 import tempfile
 from pathlib import Path
@@ -7,7 +9,10 @@
 from airflow.version import version as airflow_version
 from packaging.version import Version
 
-from cosmos.constants import DEFAULT_COSMOS_CACHE_DIR_NAME, DEFAULT_OPENLINEAGE_NAMESPACE
+from cosmos.constants import (
+    DEFAULT_COSMOS_CACHE_DIR_NAME,
+    DEFAULT_OPENLINEAGE_NAMESPACE,
+)
 
 # In MacOS users may want to set the envvar `TMPDIR` if they do not want the value of the temp directory to change
 DEFAULT_CACHE_DIR = Path(tempfile.gettempdir(), DEFAULT_COSMOS_CACHE_DIR_NAME)
@@ -23,6 +28,11 @@
 enable_cache_profile = conf.getboolean("cosmos", "enable_cache_profile", fallback=True)
 dbt_profile_cache_dir_name = conf.get("cosmos", "profile_cache_dir_name", fallback="profile")
 
+# Experimentally adding `remote_cache_dir` as a separate entity in the Cosmos 1.6 release to gather feedback.
+# This will be merged with the `cache_dir` config parameter in upcoming releases.
+remote_cache_dir = conf.get("cosmos", "remote_cache_dir", fallback=None)
+remote_cache_dir_conn_id = conf.get("cosmos", "remote_cache_dir_conn_id", fallback=None)
+
 try:
     LINEAGE_NAMESPACE = conf.get("openlineage", "namespace")
 except airflow.exceptions.AirflowConfigException:

dev/dags/example_cosmos_cleanup_dag.py

@@ -8,7 +8,7 @@
 
 from airflow.decorators import dag, task
 
-from cosmos.cache import delete_unused_dbt_ls_cache
+from cosmos.cache import delete_unused_dbt_ls_cache, delete_unused_dbt_ls_remote_cache_files
 
 
 @dag(
@@ -28,6 +28,15 @@ def clear_db_ls_cache(session=None):
 
     clear_db_ls_cache()
 
+    @task()
+    def clear_db_ls_remote_cache(session=None):
+        """
+        Delete the dbt ls remote cache files that have not been used for the last five days.
+        """
+        delete_unused_dbt_ls_remote_cache_files(max_age_last_usage=timedelta(days=5))
+
+    clear_db_ls_remote_cache()
+
 
 # [END cache_example]
 

docs/configuration/caching.rst

@@ -19,7 +19,7 @@ It is possible to turn off any cache in Cosmos by exporting the environment vari
 Disabling individual types of cache in Cosmos is also possible, as explained below.
 
 Caching the dbt ls output
-~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~
 
 (Introduced in Cosmos 1.5)
 
@@ -29,13 +29,24 @@ also the tasks queueing time.
 
 Cosmos 1.5 introduced a feature to mitigate the performance issue associated with ``LoadMode.DBT_LS`` by caching the output
 of this command as an  `Airflow Variable <https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/variables.html>`_.
-Based on an initial `analysis <https://github.com/astronomer/astronomer-cosmos/pull/1014>`_, enabling this setting reduced some DAGs ask queueing from 30s to 0s. Additionally, some users `reported improvements of 84% <https://github.com/astronomer/astronomer-cosmos/pull/1014#issuecomment-2168185343>`_ in the DAG run time.
+Based on an initial `analysis <https://github.com/astronomer/astronomer-cosmos/pull/1014>`_, enabling this setting reduced some DAGs task queueing from 30s to 0s. Additionally, some users `reported improvements of 84% <https://github.com/astronomer/astronomer-cosmos/pull/1014#issuecomment-2168185343>`_ in the DAG run time.
 
 This feature is on by default. To turn it off, export the following environment variable: ``AIRFLOW__COSMOS__ENABLE_CACHE_DBT_LS=0``.
 
+(Introduced in Cosmos 1.6 - Experimental feature)
+
+Starting with Cosmos 1.6.0, users can also set a remote directory path to store this cache instead of using Airflow
+Variables. To do so, you need to configure a remote cache directory. See :ref:`remote_cache_dir` and
+:ref:`remote_cache_dir_conn_id` for more information. This is an experimental feature introduced in 1.6.0 to gather
+user feedback. The ``remote_cache_dir`` will eventually be merged into the :ref:`cache_dir` setting in upcoming
+releases.
+
 **How the cache is refreshed**
 
-Users can purge or delete the cache via Airflow UI by identifying and deleting the cache key.
+If using the default Variables cache approach, users can purge or delete the cache via Airflow UI by identifying and
+deleting the cache key. In case you're using the alternative approach by setting the ``remote_cache_dir`` introduced
+in Cosmos 1.6.0, you can delete the cache by removing the specific files by identifying them using your configured path
+in the remote store.
 
 Cosmos will refresh the cache in a few circumstances:
 

docs/configuration/cosmos-conf.rst

@@ -94,6 +94,31 @@ This page lists all available Airflow configurations that affect ``astronomer-co
     - Default: ``profile``
     - Environment Variable: ``AIRFLOW__COSMOS__PROFILE_CACHE_DIR_NAME``
 
+.. _remote_cache_dir:
+
+`remote_cache_dir`_:
+    The remote directory to store the dbt cache. Starting with Cosmos 1.6.0, you can store the `dbt ls` output as cache
+    in a remote location (an alternative to the Variable cache approach released previously since Cosmos 1.5.0)
+    using this configuration. The value for the remote cache directory can be any of the schemes that are supported by
+    the `Airflow Object Store <https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/objectstorage.html>`_
+    feature introduced in Airflow 2.8.0 (e.g. ``s3://your_s3_bucket/cache_dir/``, ``gs://your_gs_bucket/cache_dir/``,
+    ``abfs://your_azure_container/cache_dir``, etc.)
+
+    This is an experimental feature available since Cosmos 1.6 to gather user feedback and will be merged into the
+    ``cache_dir`` setting in upcoming releases.
+
+    - Default: ``None``
+    - Environment Variable: ``AIRFLOW__COSMOS__REMOTE_CACHE_DIR``
+
+.. _remote_cache_dir_conn_id:
+
+`remote_cache_dir_conn_id`_:
+    The connection ID for the remote cache directory. If this is not set, the default Airflow connection ID identified
+    for the scheme will be used.
+
+    - Default: ``None``
+    - Environment Variable: ``AIRFLOW__COSMOS__REMOTE_CACHE_DIR_CONN_ID``
+
 [openlineage]
 ~~~~~~~~~~~~~