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Encountering the `Java command not found` error while running Airflow on the Windows Subsystem for Linux? Learn how to properly install Java and set environment variables to fix the issue.
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This video is based on the question https://stackoverflow.com/q/64592601/ asked by the user 'Smith' ( https://stackoverflow.com/u/13883723/ ) and on the answer https://stackoverflow.com/a/64610941/ provided by the user 'Smith' ( https://stackoverflow.com/u/13883723/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the Java Command Not Found Error in Airflow on Windows Subsystem for Linux

When you’re using Apache Airflow to automate workflows, encountering an error can be frustrating—especially when you are also a newcomer to this powerful tool. One such common issue is the Java command not found error when trying to execute a Java program through an Airflow task. If you’ve set everything correctly but still run into problems, you’re not alone. Let’s dive into the details of this issue and discover how to fix it.

Understanding the Issue

The error usually occurs when:

Java is not installed in the Windows Subsystem for Linux (WSL).

The JAVA_HOME environment variable is not set correctly.

Despite having Java installed on your Windows system, it’s important to remember that WSL operates in its own environment. This means any software installations, including Java, should also be performed inside WSL to be recognized.

Steps to Resolve the Error

1. Install Java on Windows Subsystem for Linux

To ensure that Airflow can access Java, you need to install it within your WSL distribution. Follow these steps:

Open your WSL terminal (e.g., Ubuntu).

Update your package repository:

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

Install Java (choose your desired version, e.g., OpenJDK):

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

2. Set Up the JAVA_HOME Environment Variable

After installing Java, you should set the JAVA_HOME environment variable so that Airflow can find Java easily. Here’s how to do it:

Open your WSL terminal.

Find the Java installation path:

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

This command will show you the path of the installed Java version, usually something like /usr/lib/jvm/java-11-openjdk-amd64. Note this path.

Open your .bashrc or .bash_profile file to edit:

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

Add the following lines at the end of the file, replacing /path/to/java with your noted path:

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

Save the changes and exit the editor (for nano: press CTRL + X, then Y, and Enter).

Refresh your terminal session by running:

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

3. Restart Airflow

Now that you have Java installed and the JAVA_HOME variable set up, restart your Airflow scheduler. You can do this by stopping and starting the scheduler service, or simply by rerunning your Airflow job.

4. Test Your Airflow Task

Finally, rerun your Airflow DAG that includes the Java command. If everything is configured correctly, the task should locate the Java executable and run smoothly.

Conclusion

By following the above steps, users can overcome the Java command not found error in Airflow running on Windows Subsystem for Linux. It’s essential to keep in mind that installations and configurations in WSL are distinct from those on your Windows host system. With a correctly installed Java and properly configured environment variables, you will be well on your way to leveraging both Airflow and Java effectively.

If you have any additional questions or run into further issues, feel free to reach out for help or consult the Airflow documentation for more in-depth troubleshooting!