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Run a Python function on AWS EC2

This page walks you through running a function on an EC2 instance using your local code and libraries.


  • If you haven't set up the AWS CLI, install and configure it.

  • Install Meadowrun

    pip install meadowrun
    conda install -c defaults -c conda-forge -c meadowdata meadowrun

    If you're using conda on a Windows or Mac, Meadowrun won't be able to mirror your local environment because conda environments aren't cross-platform and Meadowrun runs the remote jobs on Linux. If you're in this situation, you can either switch to Pip or Poetry, or create a CondaEnvironmentFile that's built for Linux and pass that in to the mirror_local call in the next step below, like mirror_local(interpreter=CondaEnvironmentFile(...))

    poetry add meadowrun

  • Finally, set up Meadowrun resources in your AWS account.

    > meadowrun-manage-ec2 install --allow-authorize-ips
    Creating resources for running meadowrun
    Created/updated user group meadowrun_user_group. Add users to this group to allow them
    to use Meadowrun with `aws iam add-user-to-group --group-name meadowrun_user_group
    --user-name <username>`
    Created resources in 27.18 seconds

    You will need to run this as a root/Administrator account.

    In this example, we set --allow-authorize-ips which reduces the configuration we need to do but is slightly less secure. You can rerun this command later without this option to switch to the more secure configuration.

    If you decide to stop using Meadowrun, it's easy to uninstall Meadowrun.

Write a Python script to run a function remotely

Create a file called

import asyncio
import meadowrun

if __name__ == "__main__":
    result =
            # the function to run remotely
            lambda: sum(range(1000)) / 1000,
            # run on a dynamically allocated AWS EC2 instance
            # requirements to choose an appropriate EC2 instance
                logical_cpu=1, memory_gb=4, max_eviction_rate=80
    print(f"Meadowrun worked! Got {result}")

Run the script

Assuming you saved the file above as

> python -m mdr 
Size of pickled function is 40
Job was not allocated to any existing EC2 instances, will launch a new EC2 instance
Launched a new EC2 instance for the job:
t2.medium (2 CPU/4.0 GB), spot ($0.0139/hr, 2.5% eviction rate), will run 1 job/worker
Meadowrun worked! Got 499.5

The output will walk you through what Meadowrun's run_function is doing:

  • Based on the options specified in Resources and AllocEC2Instance, run_function will launch the cheapest EC2 instance type that has at least 1 CPU and 4 GB of memory, and a <80% chance of being evicted. You can set this last parameter to 0 to exclude spot instances and only use on-demand instances. The exact instance type chosen depends on current EC2 prices, but in this case Meadowrun has selected a t2.medium spot instance, and we're paying $0.0139/hr for it.

  • We didn't provide the deployment parameter, which is equivalent to specifying deployment=meadowrun.Deployment.mirror_local. This tells Meadowrun to copy your local environment and code to the provisioned EC2 instance. Meadowrun detects what kind of environment (conda, pip, or poetry) you're currently in and calls the equivalent of pip freeze to capture the libraries installed in the current environment. The EC2 instance will then create a new Docker image based on the list of libraries and cache the image for reuse in a Meadowrun-managed AWS ECR container registry. Meadowrun will also zip up your local code and send it to the EC2 instance.

  • Meadowrun runs the specified function in that environment on the remote machine and returns the result.

  • When we ran meadowrun-manage-ec2 install earlier on this page, that set up an AWS Lambda that runs periodically and turns off unused EC2 instances. If the EC2 instance we started is not reused for a few minutes, it will be terminated automatically by this Lambda.

You can also log or print to stdout in your remote function--Meadowrun will copy the remote output to the local output.

Next steps

  • In addition to run_function, Meadowrun provides other entrypoints. The most important of these is run_map, which allows you to use many EC2 instances in parallel.