#
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# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
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# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
"""
This is an example dag for using a Kubernetes Executor Configuration.
"""
from __future__ import annotations
import logging
import os
import pendulum
from airflow import DAG
from airflow.configuration import conf
from airflow.decorators import task
from airflow.example_dags.libs.helper import print_stuff
[docs]log = logging.getLogger(__name__)
try:
from kubernetes.client import models as k8s
except ImportError:
log.warning(
"The example_kubernetes_executor example DAG requires the kubernetes provider."
" Please install it with: pip install apache-airflow[cncf.kubernetes]"
)
if k8s:
with DAG(
dag_id="example_kubernetes_executor",
schedule=None,
start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
catchup=False,
tags=["example3"],
) as dag:
# You can use annotations on your kubernetes pods!
[docs] start_task_executor_config = {
"pod_override": k8s.V1Pod(metadata=k8s.V1ObjectMeta(annotations={"test": "annotation"}))
}
@task(executor_config=start_task_executor_config)
def start_task():
print_stuff()
# [START task_with_volume]
executor_config_volume_mount = {
"pod_override": k8s.V1Pod(
spec=k8s.V1PodSpec(
containers=[
k8s.V1Container(
name="base",
volume_mounts=[
k8s.V1VolumeMount(mount_path="/foo/", name="example-kubernetes-test-volume")
],
)
],
volumes=[
k8s.V1Volume(
name="example-kubernetes-test-volume",
host_path=k8s.V1HostPathVolumeSource(path="/tmp/"),
)
],
)
),
}
@task(executor_config=executor_config_volume_mount)
def test_volume_mount():
"""
Tests whether the volume has been mounted.
"""
with open("/foo/volume_mount_test.txt", "w") as foo:
foo.write("Hello")
return_code = os.system("cat /foo/volume_mount_test.txt")
if return_code != 0:
raise ValueError(f"Error when checking volume mount. Return code {return_code}")
volume_task = test_volume_mount()
# [END task_with_volume]
# [START task_with_sidecar]
executor_config_sidecar = {
"pod_override": k8s.V1Pod(
spec=k8s.V1PodSpec(
containers=[
k8s.V1Container(
name="base",
volume_mounts=[k8s.V1VolumeMount(mount_path="/shared/", name="shared-empty-dir")],
),
k8s.V1Container(
name="sidecar",
image="ubuntu",
args=['echo "retrieved from mount" > /shared/test.txt'],
command=["bash", "-cx"],
volume_mounts=[k8s.V1VolumeMount(mount_path="/shared/", name="shared-empty-dir")],
),
],
volumes=[
k8s.V1Volume(name="shared-empty-dir", empty_dir=k8s.V1EmptyDirVolumeSource()),
],
)
),
}
@task(executor_config=executor_config_sidecar)
def test_sharedvolume_mount():
"""
Tests whether the volume has been mounted.
"""
for i in range(5):
try:
return_code = os.system("cat /shared/test.txt")
if return_code != 0:
raise ValueError(f"Error when checking volume mount. Return code {return_code}")
except ValueError as e:
if i > 4:
raise e
sidecar_task = test_sharedvolume_mount()
# [END task_with_sidecar]
# You can add labels to pods
executor_config_non_root = {
"pod_override": k8s.V1Pod(metadata=k8s.V1ObjectMeta(labels={"release": "stable"}))
}
@task(executor_config=executor_config_non_root)
def non_root_task():
print_stuff()
third_task = non_root_task()
executor_config_other_ns = {
"pod_override": k8s.V1Pod(
metadata=k8s.V1ObjectMeta(namespace="test-namespace", labels={"release": "stable"})
)
}
@task(executor_config=executor_config_other_ns)
def other_namespace_task():
print_stuff()
other_ns_task = other_namespace_task()
worker_container_repository = conf.get("kubernetes_executor", "worker_container_repository")
worker_container_tag = conf.get("kubernetes_executor", "worker_container_tag")
# You can also change the base image, here we used the worker image for demonstration.
# Note that the image must have the same configuration as the
# worker image. Could be that you want to run this task in a special docker image that has a zip
# library built-in. You build the special docker image on top your worker image.
kube_exec_config_special = {
"pod_override": k8s.V1Pod(
spec=k8s.V1PodSpec(
containers=[
k8s.V1Container(
name="base", image=f"{worker_container_repository}:{worker_container_tag}"
),
]
)
)
}
@task(executor_config=kube_exec_config_special)
def base_image_override_task():
print_stuff()
base_image_task = base_image_override_task()
# Use k8s_client.V1Affinity to define node affinity
k8s_affinity = k8s.V1Affinity(
pod_anti_affinity=k8s.V1PodAntiAffinity(
required_during_scheduling_ignored_during_execution=[
k8s.V1PodAffinityTerm(
label_selector=k8s.V1LabelSelector(
match_expressions=[
k8s.V1LabelSelectorRequirement(key="app", operator="In", values=["airflow"])
]
),
topology_key="kubernetes.io/hostname",
)
]
)
)
# Use k8s_client.V1Toleration to define node tolerations
k8s_tolerations = [k8s.V1Toleration(key="dedicated", operator="Equal", value="airflow")]
# Use k8s_client.V1ResourceRequirements to define resource limits
k8s_resource_requirements = k8s.V1ResourceRequirements(
requests={"memory": "512Mi"}, limits={"memory": "512Mi"}
)
kube_exec_config_resource_limits = {
"pod_override": k8s.V1Pod(
spec=k8s.V1PodSpec(
containers=[
k8s.V1Container(
name="base",
resources=k8s_resource_requirements,
)
],
affinity=k8s_affinity,
tolerations=k8s_tolerations,
)
)
}
@task(executor_config=kube_exec_config_resource_limits)
def task_with_resource_limits():
print_stuff()
four_task = task_with_resource_limits()
(
start_task()
>> [volume_task, other_ns_task, sidecar_task]
>> third_task
>> [base_image_task, four_task]
)
