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Mehdi

10/01/2024, 10:18 AM

@Marvin How can I make prefect use the config vars specified in a .env file

Marvin

10/01/2024, 10:18 AM

Prefect can use environment variables specified in a

.env

file by leveraging the existing functionality to work with environment variables. Here’s how you can configure this in both Prefect 2.x and 3.x: 1. Prefect 2.x: - Prefect 2.x mentions using job variables within your

prefect.yaml

. You can configure environment variables by templating them in your

prefect.yaml

file using the

{{ $ENV_VAR_NAME }}

syntax. - You’ll need to ensure environment variables are available when you deploy. This means loading them into your environment using a tool like

dotenv

before running the

prefect deploy

command. Example from the documentation:

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yaml
   deployments:
   - name: demo-deployment
     entrypoint: demo_project/demo_flow.py:some_work
     work_pool:
       name: local
     job_variables:
       env:
         EXECUTION_ENVIRONMENT: "{{ $EXECUTION_ENVIRONMENT }}"
         MY_NOT_SO_SECRET_CONFIG: "{{ $MY_NOT_SO_SECRET_CONFIG }}"
     schedule: null

Then, ensure you have these variables set in your environment before running deploy:

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sh
   export EXECUTION_ENVIRONMENT=staging
   export MY_NOT_SO_SECRET_CONFIG=plumbus
   prefect deploy

References: - Prefect 2.x documentation on using .env - Prefect 2.x documentation on variables 2. Prefect 3.x: - Prefect 3.x follows a similar pattern. You can use a

.env

file to load environment variables and then refer to them in your

prefect.yaml

. Example from the documentation:

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yaml
   deployments:
   - name: demo-deployment
     entrypoint: demo_project/demo_flow.py:some_work
     work_pool:
       name: local
     job_variables:
       env:
         EXECUTION_ENVIRONMENT: "{{ $EXECUTION_ENVIRONMENT }}"
         MY_NOT_SO_SECRET_CONFIG: "{{ $MY_NOT_SO_SECRET_CONFIG }}"
     schedule: null

Load your environment variables before deploying:

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sh
   export $(grep -v '^#' .env | xargs)
   prefect deploy -n demo-deployment

References: - Prefect 3.x documentation on using environment variables In both versions, you can use the

python-dotenv

package to load environment variables from a

.env

file into your environment:

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python
from dotenv import load_dotenv
import os

load_dotenv()  # take environment variables from .env.

# Your prefect deployment code here.

If these examples do not quite fit your needs or if you encounter any specific issues, feel free to share more details!

Mehdi

10/01/2024, 10:32 AM

@Marvin I am trying to run this CLI command

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prefect worker start --pool 'docker-work-pool'

but it should be able to read the .env file without doing a prefect login step is it possible ?

Marvin

10/01/2024, 10:33 AM

To run the Prefect CLI command to start a worker and have it read from a

.env

file without requiring a Prefect login step, you can use the

python-dotenv

package to load environment variables from a

.env

file into your environment. This approach works for both Prefect 2.x and 3.x versions. Here’s how you can do this: 1. Create your
.env
file: This file should contain your environment variables, including the Prefect API key and URL if needed.

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env
   PREFECT_API_URL=<https://api.prefect.cloud/api/accounts/<ACCOUNT-ID>/workspaces/<WORKSPACE-ID>>
   PREFECT_API_KEY=<YOUR-API-KEY>
   # Other environment variables
   YOUR_ENV_VAR=value

2. Load the
.env
file and run the Prefect worker via a script: Instead of running the command directly, you can create a simple Python script that loads the environment variables and then runs the

prefect

command using

os.system

. Here's an example of such a script:

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python
   # run_worker.py
   import os
   from dotenv import load_dotenv

   # Load environment variables from .env file
   load_dotenv()

   # Start the prefect worker
   os.system("prefect worker start --pool 'docker-work-pool'")

3. Run the script: Execute the script from the command line to start the worker:

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sh
   python run_worker.py

This will load the environment variables from the

.env

file and start the Prefect worker with the specified pool, without you needing to perform a login step manually. References for further reading: 1. Prefect 2.x: Read more about using and configuring environment variables in Prefect here. 2. Prefect 3.x: Documentation on environment variables and workers can be found here. If you have any additional questions or encounter any issues, feel free to ask!

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