Скачать или смотреть Solving DNS Issues for Kubernetes Pods and Airflow Worker Logs

Discover solutions to DNS resolution issues between Kubernetes pods and Airflow workers to ensure seamless access to logs.
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Solving DNS Issues for Kubernetes Pods and Airflow Worker Logs

When working with Kubernetes and Airflow, one common issue that users might encounter is related to DNS resolution between pods. For example, you may find that an Airflow instance running in one pod cannot access logs stored in another pod because the required hostname cannot be resolved. This guide will explore this issue in detail and provide a straightforward solution.

The Problem

Consider an Airflow pod named airflow-79d5f59644-dd4k7 trying to fetch logs from an Airflow worker pod named airflow-worker-67bcf7844b-rq7r8. Despite both pods running successfully, the Airflow instance cannot resolve the worker's hostname properly, leading to errors like:

[[See Video to Reveal this Text or Code Snippet]]

This error arises because the DNS name for the worker pod is not being recognized in the context of the Airflow pod. Even if you can access the worker using a direct IP, validating the DNS name is essential for proper scaling and networking within Kubernetes.

Understanding Kubernetes DNS

Kubernetes has a built-in DNS service that allows for the following:

Pod-to-pod communication using a defined naming convention.

Automatic creation of DNS records for services and pods.

However, when pods are created with random names, like the airflow-worker in this case, DNS resolution may fail if Airflow does not recognize how to access those services.

Solution

To resolve this issue, take the following steps:

Step 1: Set Up Environment Variable for Worker Pods

Add an environment variable to your Airflow worker pod’s deployment.yaml file that specifies how to resolve the hostnames. This can be done by adding the following snippet to your worker configuration:

[[See Video to Reveal this Text or Code Snippet]]

This setting instructs Airflow to utilize the IP address of the pods instead of relying solely on the hostnames, greatly reducing the DNS resolution failures.

Step 2: Modify the Airflow Configuration

You can also change the Airflow configuration settings directly in the airflow.cfg file if you prefer not to manage environment variables. Adjust the same parameter to ensure that logs are accessed via the correct method.

Step 3: Validate Connectivity

Once you implement the changes, it’s essential to validate that everything works properly. Here’s how to do it:

Get inside the Airflow Pod: Use the command below to open a shell in the Airflow pod:

[[See Video to Reveal this Text or Code Snippet]]

Run a connectivity test: Attempt to fetch logs using the worker's IP address:

[[See Video to Reveal this Text or Code Snippet]]

Check for Log Access: Make sure that you get a success response rather than an error indicating that the logs could not be fetched.

Key Takeaways

Ensure Kubernetes DNS is properly configured for your pods.

Use Airflow environment variables for robust hostname resolution.

Verifying connectivity through a simple curl command can help confirm proper setups.

By following the steps outlined above, you can effectively resolve the DNS-related issues between your Kubernetes pods and Airflow worker logs. This ensures smooth operation without interruptions in your workflow.