Extend init_containers defined in pod_override (#17537)

Needs to extend also the init_containers not just override (e.g. git sync and similar init_containers will stay)

With that change if you define a pod_override and specifies the "init_containers" attribute it will extend the base init_containers with the new ones instead of overwriting them. That is to keep the dag git sync init_containers or other pre-defined init_containers based on the template or the configuration.

Author: repocho

airflow/kubernetes/pod_generator.py

@@ -287,7 +287,8 @@ def reconcile_specs(
             client_spec.containers = PodGenerator.reconcile_containers(
                 base_spec.containers, client_spec.containers
             )
-            merged_spec = extend_object_field(base_spec, client_spec, 'volumes')
+            merged_spec = extend_object_field(base_spec, client_spec, 'init_containers')
+            merged_spec = extend_object_field(base_spec, merged_spec, 'volumes')
             return merge_objects(base_spec, merged_spec)
 
         return None

docs/apache-airflow/executor/kubernetes.rst

@@ -113,7 +113,7 @@ create a V1pod with a single container, and overwrite the fields as follows:
     :start-after: [START task_with_volume]
     :end-before: [END task_with_volume]
 
-Note that volume mounts, environment variables, ports, and devices will all be extended instead of overwritten.
+Note that the following fields **will all be extended** instead of overwritten. From *spec*: volumes, and init_containers. From *container*: volume mounts, environment variables, ports, and devices.
 
 To add a sidecar container to the launched pod, create a V1pod with an empty first container with the
 name ``base`` and a second container containing your desired sidecar.

tests/kubernetes/test_pod_generator.py

@@ -631,6 +631,14 @@ def test_reconcile_specs(self):
         client_spec.active_deadline_seconds = 100
         assert client_spec == res
 
+    def test_reconcile_specs_init_containers(self):
+        base_spec = k8s.V1PodSpec(containers=[], init_containers=[k8s.V1Container(name='base_container1')])
+        client_spec = k8s.V1PodSpec(
+            containers=[], init_containers=[k8s.V1Container(name='client_container1')]
+        )
+        res = PodGenerator.reconcile_specs(base_spec, client_spec)
+        assert res.init_containers == base_spec.init_containers + client_spec.init_containers
+
     def test_deserialize_model_file(self):
         path = sys.path[0] + '/tests/kubernetes/pod.yaml'
         result = PodGenerator.deserialize_model_file(path)