@Marvin How can we pass environment variables to Prefect V3 from the worker start command? I have tried a .cmd script that sets the variable and boots the worker. I cannot access the variable via prefect.context.env, running a basic python script also does not see it. I must pass it with --env, but when I try use --env with Prefect Worker is will not boot due to unrecognised argument

It seems you're facing issues with passing environment variables to a Prefect V3 worker via the command line. The

--env

flag isn't recognized for this purpose in the Prefect worker start command. Here's a concise way to approach this: 1. Setting Environment Variables: Prefect V3 does not directly support an

--env

flag for passing environment variables when starting a worker. Instead, you should set environment variables in your shell before starting the worker. This can be done using a script or directly in the command line. 2. Using Shell Scripts: If you're using a

.cmd

script, ensure that the environment variables are exported correctly before the command to start the worker. For example:

cmd
   set MY_ENV_VAR=value
   prefect worker start ...

3. Python Access: To access these environment variables in your Prefect flows, use Python's

os.environ

instead of

prefect.context.env

. This is because environment variables set at the OS level are accessed through

os.environ

. 4. Documentation and Issues: Unfortunately, the Prefect documentation doesn't provide direct support for passing environment variables via the worker start command. You can refer to the Prefect documentation on settings and profiles and worker concepts for more details. If you're encountering persistent issues, you might consider raising a question on Prefect's GitHub issues for more tailored support.

@Marvin Thank you, I am trying to pass this variable to be used in a deployment step. We are using the set_working_directory pull step with "{{ prefect.context.env.PREFECT_WORKER_PID }}". How would I make the environment variable accessible to this step when booting from shell?

To make an environment variable accessible to a deployment step using the

set_working_directory

pull step in Prefect V3, you need to ensure that the environment variable is set on the machine where the deployment is executed. Here's how you can achieve this: 1. Set Environment Variables: Ensure the environment variable is set in the shell before you run the Prefect deployment command. For example:

bash
   export PREFECT_WORKER_PID=your_value
   prefect deployment run your_deployment_name

2. Use Environment Variables in Deployment: In your

prefect.yaml

or deployment configuration, you can reference environment variables using the

{{ $ENV_VAR_NAME }}

syntax. For example:

yaml
   pull:
     - prefect.deployments.steps.set_working_directory:
         directory: "{{ $PREFECT_WORKER_PID }}"

3. Deployment Execution: When you execute the deployment, Prefect will substitute

{{ $PREFECT_WORKER_PID }}

with the value of the environment variable set in your shell. 4. Common Gotchas: Remember that Prefect 3.x has replaced agents with workers and uses work pools instead of infrastructure blocks. Ensure that your environment is properly configured to reflect these changes. For more details, you can refer to the Prefect documentation on deployment customization and variables. If you follow these steps, the environment variable should be accessible to the deployment step when booting from the shell.

@Marvin You have saved the day, the key was to use {{ $PREFECT_WORKER_PID }} in the deployment step. Thank you

You're welcome. It's nice to be of use occasionally. If you have any more questions or need further assistance with Prefect or anything else, feel free to ask. Enjoy your day!