You may want to save data produced by your tasks. Beam provides an abstraction called Output, which allows you to save files or directories and generate public URLs to access them.

​
Saving Files

To save an Output, you can write any filetype to Beam’s /tmp directory.

Here’s what your code might look like:

from beam import function, Output


@function()
def save_output():
    # File is saved to /tmp directory
    file_name = "/tmp/my_output.txt"

    # Write to new text file
    with open(file_name, "w") as f:
        f.write("This is an output, a glorious text file.")

    # Save output
    output_file = Output(path=file_name)
    output_file.save()

    # Generate and return a public URL
    public_url = output_file.public_url(expires=400)
    return {"output_url": public_url}

​
Directories

You can also create public URLs for directories, by passing in a directory path:

# Generate a public URL for a directory
file_path = "./tmp/waveforms"
output = Output(path=file_path)
output.save()

# Returns https://app.beam.cloud/output/id/abe0c95a-2cd1-40b3-bace-9225f2c79c6d
output_url = output.public_url()

​
PIL Images

If your app uses PIL, Output includes a wrapper around PIL to simplify the process of generating a public URL for the PIL image file:

# Save a PIL image
image = pipe(...)

# Persist the PIL image to an Output
output = Output.from_pil_image(image).save()

Here’s a full example:

from beam import Image as BeamImage, Output, function


@function(
    image=BeamImage(
        python_packages=[
            "pillow",
        ],
    ),
)
def save_image():
    from PIL import Image as PILImage

    # Generate PIL image
    pil_image = PILImage.new(
        "RGB", (100, 100), color="white"
    )  # Creating a 100x100 white image

    # Save image file
    output = Output.from_pil_image(pil_image)
    output.save()

    # Retrieve pre-signed URL for output file
    url = output.public_url(expires=400)
    print(url)

    # Print other details about the output
    print(f"Output ID: {output.id}")
    print(f"Output Path: {output.path}")
    print(f"Output Stats: {output.stat()}")
    print(f"Output Exists: {output.exists()}")

    return {"image": url}


if __name__ == "__main__":
    save_image()

When you run this function, it will return a pre-signed URL to the image:

https://app.beam.cloud/output/id/abe0c95a-2cd1-40b3-bace-9225f2c79c6d

​
Generating Public URLs

Your app might return files from the API, such as images or MP3s. You can use Output to generate a public URL to access the content.

​
Expiring Public URLs

You can pass an optional expires parameter to output.public_url to control how long to persist the file before it is deleted.

By default, public URLs are automatically deleted after 1 hour.
# Delete public URL after 5 minutes
output.public_url(expires=300)

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