[AIRFLOW-2532] Support logs_volume_subpath for KubernetesExecutor

The kubernetes section in the configuration file
supports
logs_volume_subpath for KubernetesExecutor.

Closes apache#3430 from imroc/AIRFLOW-2532

airflow/config_templates/default_airflow.cfg

@@ -559,6 +559,9 @@ dags_volume_subpath =
 # For DAGs mounted via a volume claim (mutually exclusive with volume claim)
 dags_volume_claim =
 
+# For volume mounted logs, the worker will look in this subpath for logs
+logs_volume_subpath =
+
 # A shared volume claim for the logs
 logs_volume_claim =
 

airflow/contrib/executors/kubernetes_executor.py

@@ -133,6 +133,11 @@ def __init__(self):
         self.dags_volume_subpath = conf.get(
             self.kubernetes_section, 'dags_volume_subpath')
 
+        # This prop may optionally be set for PV Claims and is used to locate logs
+        # on a SubPath
+        self.logs_volume_subpath = conf.get(
+            self.kubernetes_section, 'logs_volume_subpath')
+
         # This prop may optionally be set for PV Claims and is used to write logs
         self.base_log_folder = configuration.get(self.core_section, 'base_log_folder')
 

airflow/contrib/kubernetes/worker_configuration.py

@@ -128,7 +128,8 @@ def _construct_volume(name, claim, subpath=None):
             ),
             _construct_volume(
                 logs_volume_name,
-                self.kube_config.logs_volume_claim
+                self.kube_config.logs_volume_claim,
+                self.kube_config.logs_volume_subpath
             )
         ]
         volume_mounts = [{

scripts/ci/kubernetes/kube/configmaps.yaml

@@ -185,7 +185,9 @@ data:
     git_user =
     git_password =
     dags_volume_claim = airflow-dags
+    dags_volume_subpath =
     logs_volume_claim = airflow-logs
+    logs_volume_subpath =
     in_cluster = True
     namespace = default
     gcp_service_account_keys =