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Hi <@ULVA73B9P> I have three different repos each ...
# ask-marvin
m
Hi @Marvin I have three different repos each with their own poetry virtual environment running on a remote windows server, the code is stored on the remote machine. When I'm running a worker outside any of those repos it is not able to recognize the virtual environment, can you help?
m
Certainly! It sounds like you're running into an issue related to the activation of virtual environments when using Poetry, especially in contexts like Prefect workers running remotely. Here are some steps and considerations to help resolve this: 1. Activate the Virtual Environment: Before starting your Prefect worker, you'll need to activate the appropriate Poetry virtual environment. This can typically be done by navigating to the project directory and running 
poetry shell
or directly activating the virtual environment using the path provided by 
poetry env info --path
. 2. Environment Variables: Since you're running your worker outside of the project directories, ensure that the environment variables pointing to the correct Python interpreter and dependencies are set. You can set the 
PYTHONPATH
and other necessary environment variables in your worker's execution context. 3. Configuration of Prefect Worker: - When configuring your Prefect worker, you may specify the path to the Python interpreter from the virtual environment. This ensures that the worker uses the correct environment. Typically, something like 
path\to\your\env\Scripts\python.exe
should be used. 4. Scripts and Task Definitions: If your Prefect tasks or flows depend on any specific packages or configurations, ensure these are exportable and can be recognized by the worker no matter where it's executed. 5. Check Poetry Settings: Ensure that each virtual environment has been properly set up and is isolated using 
poetry config --list
. This can help confirm there's no misconfiguration affecting the interpreter selection. Here's a highlighted step to help you check and activate a Poetry virtual environment manually: - Navigate to your project directory and run the following command:
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bash
  poetry env info --path
Use this path to activate your virtual environment manually in your scripts or Prefect worker setup. Lastly, if there's specific functionality or tasks related to Prefect you're struggling with, please let me know. I could also help you find information directly from the Prefect documentation. Sometimes, remote execution can have additional nuances depending on the version of Prefect you're using. If it comes to that, I can dive into some detailed Prefect-specific solutions for you.
m
@Marvin The code runs fine when I'm running the worker from inside the folders proving the venv is fine, the problem is I'd like the Prefect Worker to be able to run all three projects. We accomplished this earlier with agents running from each project.
m
To have a single Prefect worker capable of running tasks from multiple projects, each with its own Poetry virtual environment, you can employ a strategy that leverages dynamic environment management. Here are some approaches to achieve this: 1. Dynamic Activation: Before executing a task, dynamically activate the appropriate Poetry virtual environment based on the task or flow being executed. This can be done by scripting the activation process in your flow setup or task execution logic. You may use Python subprocesses to execute 
poetry shell
or activate the appropriate virtual environment. 2. Environment Customization in Prefect Flows/Tasks: - Within your Prefect flow or task, make use of environment variables to activate the correct environment. You can manually specify commands in your task's run function. - For instance, each task can include logic like this to activate the required environment:
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python
     import subprocess

     def run_task():
         subprocess.run(["poetry", "run", "task-specific-command"])
3. Prefect Job Templates: If you're using a setup that supports job templates or custom job configurations, integrate the environment-specific activation commands within these templates. 4. Task-specific Configuration: Extend your Prefect task definitions to accept a parameter that indicates which project's environment to activate. This allows conditional execution based on the passed parameter. 5. Use of Process Executors: Leverage Prefect’s process-based executors which allow the execution of tasks in separate subprocesses. This approach allows you to set up a subprocess that runs inside the desired virtual environment. Utilizing these strategies, you can achieve a setup where a single Prefect worker can handle tasks from multiple projects while ensuring each task runs within its proper environment. If you have further specifics about how you're managing task execution or particular difficulties you face, I can also help look into Prefect documentation or community solutions for more tailored advice. Just let me know!
n
hi @Mads you'd probably want a 
pull
step here that sets up / activates the right venv for the deployment for example, like this but only some command to activate your venv instead of 
pwd
m
That makes sense @Nate thanks, I'll look into how that's done, you wouldn't happen to have an example laying around?
n
I don't have exactly that as an example, are you familiar with uv by chance?
m
I'm not, but from a quick glance it looks wonderful, sadly i'm stuck with poetry :I
n
aha! uv is really great at "run this process in an ephemeral venv" but lemme see if I can find a more poetry conducive example
m
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pull:
- prefect.deployments.steps.run_shell_script:
    id: dynamic-dir
    script: |
      powershell -Command "& { $currentDir = [System.IO.Directory]::GetCurrentDirectory(); if ($currentDir  -match '^(C:\\Users\\[^\\]+)(\\.*)') {$matches[1]}}"
    stream_output: true
- prefect.deployments.steps.set_working_directory:
    directory: "{{ dynamic-dir.stdout }}\\Repos\\repox"
This is my current pull section, which could also be the cause of the issues, as I'm doing some powershell action here to try and make it dynamic so we don't have to hardcode the path on the remote. Could this be the cause of the issues, because I feel like it shouldn't really be an issue atleast it wasn't back when we were on prefect 2x
Also UV sounds really good at a closer look, I'll make sure to keep that in mind if the team ever needs a new package manager
n
yeah fwiw i wrote a prefect worker that uses uv to run each flow run in a venv and it works nicely. but anyways, im not a powershell expert but I would recommend something like this example where you may want to replace the latter 
pip_install_requirements
step with 
run_shell_script
to use whatever poetry command sets up a venv from requirements / pyproject
m
I've been playing around with this and feel pretty close. @Marvin Can you help me get the rest of the way with this:
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- prefect.deployments.steps.run_shell_scripts:
  id: activate-poetry-venv
  script: |
    powershell -Command "& {
      $poetryEnvPath = (poetry env info --path);
      Write-Host 'Debug: Poetry environment path = ' $poetryEnvPath;
      $activateScript = Join-Path $poetryEnvPath 'Scripts\\Activate.ps1';
      Write-Host 'Debug: Activation script path = ' $activateScript;
      . $activateScript;
    }"
  stream_output: true
It errors out with ValueError: Step has unexpected additional keys: id, script, stream_output, but when I run the powershell command inside a powershell prompt it runs no issue.
m
It looks like you're encountering syntax issues with your 
prefect.deployments.steps.run_shell_scripts
configuration. The error message indicates that the step has unexpected keys. Here's how you can adjust your setup based on the Prefect 3.x documentation: 1. Understanding 
run_shell_scripts
Step: According to the Prefect 3.x documentation, the 
run_shell_script
step is used to execute shell commands in a subprocess and return the standard output and error. The documentation didn't mention using keys like 
id
, 
script
, or 
stream_output
directly as you've listed. 2. Correct Syntax: You might need to adjust your deployment YAML to follow the expected syntax. Here's a more generic example that aligns with what Prefect expects based on similar excerpts:
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yaml
   - prefect.deployments.steps.run_shell_script:
       script: |
         powershell -Command "& {
           $poetryEnvPath = (poetry env info --path);
           Write-Host 'Debug: Poetry environment path = ' $poetryEnvPath;
           $activateScript = Join-Path $poetryEnvPath 'Scripts\\Activate.ps1';
           Write-Host 'Debug: Activation script path = ' $activateScript;
           . $activateScript;
         }"
       expand_env_vars: true
3. Script Execution Notes: The 
expand_env_vars: true
setting is relevant if you're leveraging environment variables within your script. 4. Deployment Mechanics: Whenever you run a 
prefect deploy
, ensure the YAML is correctly formatted and follows the sequence of build, push, and any template steps outlined by your Prefect configuration. If any of these adjustments don't solve the problem, please provide more details or check that the script runs smoothly outside of Prefect, then tweak it accordingly in the Prefect deployment. If there's anything else specifically troubling you, just let me know, and I'll dig some more or give you other suggestions! Here's where I found some useful insights: Prefect 3.x Documentation.
m
@Marvin I still get a similar error, just with valueError: Step has unexpected additional keys: script, expand_env_vars. I have two different prefect.deployments.steps.run_shell_script in my pull section, am I not able to do that?
m
It seems you're having trouble due to syntax or configuration issues surrounding the 
run_shell_script
step in your Prefect deployment. From what's been gathered, here's how you can address this problem: 1. Utility Steps in Prefect YAML: Based on the documentation, 
run_shell_script
steps can be used within build, push, or pull actions to manage deployment lifecycle tasks. However, the documentation does not specify restrictions on multiple 
run_shell_script
steps within the same section, such as "pull." Therefore, it's technically possible to have multiple steps, but they must adhere strictly to the required syntax. 2. Syntax Structure: Ensure that each 
run_shell_script
step is defined correctly without introducing unexpected keys. The most relevant parameters seem to stick to 
script
, and using these with correct indentation and structure within the YAML is crucial. Here’s a refined example based on the syntax guidelines:
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yaml
pull:
  - prefect.deployments.steps.run_shell_script:
      script: |
        powershell -Command "& {
          $poetryEnvPath = (poetry env info --path);
          Write-Host 'Debug: Poetry environment path = ' $poetryEnvPath;
          $activateScript = Join-Path $poetryEnvPath 'Scripts\\Activate.ps1';
          Write-Host 'Debug: Activation script path = ' $activateScript;
          . $activateScript;
        }"
  - prefect.deployments.steps.run_shell_script:
      script: |
        # Another script here
3. Common Mistakes: Double-check that none of the scripts include unexpected parameters and that indentation is correct. YAML is whitespace-sensitive, and any deviation from the proper structure can cause issues. 4. Deployment Mechanics: Remember, when you run 
prefect deploy
, make sure every section of the 
prefect.yaml
file resolves all references and follows the proper order, such as build, push, and pull. If those points don't resolve the issue, double-check for any uncommon syntax errors or edge-happenings in your specific use case. Here's the Prefect 3.x YAML Documentation which provides context on how these configurations should look. If you need further assistance, feel free to ask.
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