How to use pod_template_file parameter with KubernetesPodOperator in airflow 2?

Question

I am running airflow via MWAA on aws and the worker nodes are running k8s. The pods are getting scheduled just fine but I am trying to use pod_template_file with KubernetesPodOperator, it's giving me a bunch of uncertain behavior.

My template file stored in S3

apiVersion: v1
kind: Pod
metadata:
  name: app1
  namespace: app1
spec:
  containers:
  - name: base
    image: "alpine:latest"
    command: ["/bin/sh"]
    args: ["-c", "while true; do echo hi>> /data/app.log; sleep 5; done"]
    volumeMounts:
    - name: persistent-storage
      mountPath: /data
  volumes:
  - name: persistent-storage
    persistentVolumeClaim:
      claimName: claim1

My DAG file

t_1 = KubernetesPodOperator(
    task_id=job_name_1,
    namespace="app",
    name=job_name_1,
    get_logs=True,
    is_delete_operator_pod=False,
    in_cluster=False,
    config_file=kube_config_path,
    startup_timeout_seconds=240,
    cluster_context='test',
    pod_template_file="/opt/airflow/pod_template_file_example-1.yaml",
    dag=dag)

When I go with this, I get an error that the pod spec is invalid as it's missing image field. This is surprising as image is present in pod-template.

I also tried below, it works, but it totally ignores the pod-template file and spins up a alpine container and exits. So looks like it's totally ignoring the pod_template_file param.

full_pod_spec = k8s.V1Pod(
    metadata=metadata_2,
    spec=k8s.V1PodSpec(containers=[
        k8s.V1Container(
            name="base",
            image="alpine:latest",
        )
    ], ))

t_1 = KubernetesPodOperator(
    task_id=job_name_1,
    namespace="mlops",
    name=job_name_1,
    get_logs=True,
    is_delete_operator_pod=False,
    in_cluster=False,
    config_file=kube_config_path,
    startup_timeout_seconds=240,
    cluster_context='aws',
    full_pod_spec=full_pod_spec,
    pod_template_file="/opt/airflow/pod_template_file_example-1.yaml",
    dag=dag)

What is the correct way to reference a pod_template_file in KubernetesPodOperator in airflow?

References : medium

YwH · Answer 1 · 2023-03-20T07:26:21.253

Never used MWAA on aws before. But your problem seems to be:

Is your template file stored in S3 available to the DAG script file through path "/opt/airflow/pod_template_file_example-1.yaml"?

Check out the docs for Difference between KubernetesPodOperator and Kubernetes object spec.

So KubernetesPodOperator just creates the equivalent YAML/JSON object spec for the Pod, and it contains 4 types of arguments for this purpose with the following order of precedence:

KubernetesPodOperator arguments, like name/namespace/image...;
full pod spec, which is arg: full_pod_spec;
pod template file, which is arg: pod_template_file;
airflow connection;

How to use pod_template_file parameter with KubernetesPodOperator in airflow 2?

1 Answers1