Airflow on Kubernetes: "ERROR: relation "log" does not exist" – Solved!
The Problem:
You're running Airflow on Kubernetes, and when you try to access the UI or execute tasks, you encounter the dreaded "ERROR: relation "log" does not exist" message. This error means that the Airflow database cannot find the table where it stores task logs, which is essential for monitoring and debugging your workflows.
The Scenario:
Imagine you've successfully deployed Airflow on Kubernetes, and you're excited to start using it. But, when you navigate to the Airflow UI, you're greeted with this error message. Here's what might be happening:
# airflow.cfg
[core]
sql_alchemy_conn=postgresql://airflow:airflow@postgres:5432/airflow
You've defined your database connection in your airflow.cfg file, but the database has not been initialized properly, leading to missing tables like "log".
Troubleshooting:
-
Database Initialization: The most common reason for this error is that the Airflow database has not been initialized. Airflow needs to create specific tables within the database to store metadata, logs, and other information.
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Missing Permissions: If you're using a PostgreSQL database, it's crucial to ensure that the Airflow user has sufficient permissions to create and access the necessary tables.
-
Incorrect Configuration: Verify that your
sql_alchemy_connsetting in theairflow.cfgfile is correctly pointing to your database instance.
Solutions:
Here are the steps to resolve the "relation "log" does not exist" error:
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Initialize the Airflow Database:
-
Using the CLI: You can initialize the database using the Airflow CLI:
airflow initdb -
Manually: If the CLI doesn't work, you can manually create the tables using SQL commands. You can find the SQL schema in the
airflow/airflow/sqldirectory of your Airflow installation.
-
-
Granting Permissions (PostgreSQL):
-
Ensure that the user defined in your
sql_alchemy_connhas the necessary privileges. You can use the following SQL command to grant the user all privileges:GRANT ALL PRIVILEGES ON DATABASE airflow TO airflow;
-
-
Verify the Configuration:
- Double-check that the database connection details in your
airflow.cfgfile are correct. Ensure you have the right hostname, database name, username, and password.
- Double-check that the database connection details in your
Additional Considerations:
- Containerization: If you are using containerized environments like Docker or Kubernetes, ensure that the correct environment variables are set for the database connection.
- Persistence: If your database is not persistent (e.g., ephemeral volumes), the database will be recreated each time your container restarts. You'll need to implement a persistent storage solution for your database.
Conclusion:
The "relation "log" does not exist" error in Airflow on Kubernetes often stems from missing database initialization or insufficient database permissions. By following the steps outlined above, you can diagnose and resolve this error, ensuring that Airflow can successfully store task logs and provide the necessary monitoring and debugging capabilities.
