@Marvin Prefect3, pull step at prefect.deployments.steps.pip_install_requirements, any ways to install requirements to my virtualenv created with

python -m venv venv

?

To install requirements into a virtual environment created with

python -m venv venv

using the

pip_install_requirements

step in Prefect 3.x, you generally follow the deployment mechanics outlined in the Prefect documentation. When you set up your deployment using a

prefect.yaml

file, you can specify steps such as

pip_install_requirements

to install dependencies from a

requirements.txt

file. However, to specifically target a virtual environment, you can use a step like

run_shell_script

to activate your virtual environment and then install the requirements. Here's an example approach you could take: - Use the

run_shell_script

step to activate your virtual environment and then run the

pip

command. It might look something like this in your

prefect.yaml

under the pull section of your steps:

yaml
steps:
  - run_shell_script:
      id: install_dependencies
      command: |
        source venv/bin/activate
        pip install -r requirements.txt

This will allow the script to utilize the activated virtual environment when

pip

is called. For additional details on deploying with Prefect 3.x and using

pip_install_requirements

, you might find this part of the documentation useful: Prefect Infrastructure Concepts - prefect.yaml. And if you find bumps in the road, rest assured you’re not alone. If even robots had a "sigh" function, I'd use it all the time when dealing with virtual environments. If you need any more help, feel free to ask!

@Marvin When I started prefect worker in my

venv

, do I need

source venv/bin/activate

at that time?

When starting a Prefect worker within a virtual environment (

venv

), it is important to activate the virtual environment using

source venv/bin/activate

. Activating the virtual environment ensures that the Python interpreter and dependencies installed in that environment are used when the worker is running. The Prefect documentation mentions that if you're running a systemd service in a virtual environment, you should ensure that your

ExecPath

points to the Prefect application in the

bin

subdirectory of your virtual environment. This implies that activating the virtual environment is necessary to set the appropriate paths and environment variables. Before starting your Prefect worker, run:

source venv/bin/activate

This will make sure your virtual environment is correctly set up and all dependencies required by your flows and tasks are available. For more details on running Prefect in different environments, you can check this link to the documentation: Daemonizing Processes. And remember, robots don't technically need to worry about paths, but we prefer to do so anyway, just for kicks. If you have more questions, just let me know!

hi @syakesaba - are you using a process worker?

Hi @Nate yes, I use process worker

do you have a situation where you have N deployments, each with their own requirements.txt and you want to essentially run each flow run in its own ephemeral venv?

Yes. *I don't use Docker worker

hi @syakesaba! ok this is a pattern that I think we should make easier for the local process worker (since we have lately begun sneaking

uv

into prefect itself) but this is technically possible now like this

deployments:
  - name: deployment-1
    entrypoint: examples/run_a_prefect_worker/on_local/emoji_flow.py:uses_emoji
    work_pool:
      name: local
      job_variables:
        command: uv run --with emoji python -m prefect.engine
    pull:
      - prefect.deployments.steps.git_clone:
          repository: <https://github.com/zzstoatzz/prefect-pack.git>

the key idea is to use

uv

to install ephemeral dependencies for the

command

that starts the flow run process im not exactly sure how you'd use the

--with-requirements

flag here, or how you'd do it with

pip

but hopefully this is somewhat helpful - ill return to this later since with

uv

we should be able to support ephemeral deps in a more first class way with the process worker

@Nate Thank you I really appreciate your help. I will try that!