Container Support with fal

fal now supports running functions within custom Docker containers, providing greater flexibility and control over your environment.

Example: Using Custom Containers with fal functions

Here’s a complete example demonstrating how to use custom containers with fal.

import fal

from fal.container import ContainerImage

dockerfile_str = """
FROM python:3.11

RUN apt-get update && apt-get install -y ffmpeg
RUN pip install pyjokes ffmpeg-python
"""

@fal.function(
    kind="container",
    image=ContainerImage.from_dockerfile_str(dockerfile_str),
)
def test_container():
    # A dependency that might have complex installation requirements.
    import ffmpeg
    (
        ffmpeg.input("input.mp4")
        .filter('thumbnail', n=300)
        .output("thumbnail_filter_2.png")
        .run()
    )
    # And tell me a joke!
    import pyjokes
    print(pyjokes.get_joke())

    print("done")

if __name__ == "__main__":
    test_container()

Detailed Explanation

1. Importing fal and ContainerImage:

import fal
from fal.container import ContainerImage

2. Creating a Dockerfile String: A multi-line string (dockerfile_str) is defined, specifying the base image as python:3.11, and installing ffmpeg and pyjokes packages.

dockerfile_str = """
FROM python:3.11

RUN apt-get update && apt-get install -y ffmpeg
RUN pip install pyjokes ffmpeg-python
"""

Version mismatch

Ensure that the Python version in the Dockerfile matches the Python version in your local environment that you use to run the function.

This is required to avoid any compatibility issues. We use pickle to serialize the function under the hood, and the Python versions must match to avoid any serialization issues.

That being said, we are constantly working on improving this experience.

Alternatively, you can use a Dockerfile path to specify the Dockerfile location:

import pathlib
PWD = Path(__file__).resolve().parent
@fal.function(
    kind="container",
    image=ContainerImage.from_dockerfile(f"{PWD}/Dockerfile"),
)
def test_container():
    ...

3. Defining the Container Function: The @fal.function decorator specifies that this function runs in a container. The image parameter is set using ContainerImage.from_dockerfile_str(dockerfile_str), which builds the Docker image from the provided Dockerfile string.

   @fal.function(
       kind="container",
       image=ContainerImage.from_dockerfile_str(dockerfile_str),
   )

4. Function Implementation: Inside test_container, the ffmpeg library processes a video to create a thumbnail image. Then, it uses pyjokes to print a random joke.

   def test_container():
       import ffmpeg
       (
           ffmpeg.input("input.mp4")
           .filter('thumbnail', n=300)
           .output("thumbnail_filter_2.png")
           .run()
       )
       import pyjokes
       print(pyjokes.get_joke())
   
       print("done")

Running the Function

To run the function, save the code to a file (e.g., test_container.py) and execute it using the fal run command:

fal run test_container.py

or directly from the Python interpreter:

python test_container.py

This example demonstrates how to leverage Docker containers in fal, enabling customized execution environments for your functions. For more details and advanced usage, refer to the fal Container Documentation.