Hi I have a project with a simple python file that is containerized with a Dockerfile. The dockerfile is:

FROM python:3.9-slim

    WORKDIR /app

    COPY . .

    RUN pip install --no-cache-dir -r requirements.txt

    CMD ["python", "prefect-test.py"]

prefect-test.py is a simple file that print a message. If I build the image locally with Docker Desktop and run it, it works. I already pushed it on docker hub in a public repo. Now I want to start a Prefect server versione 3 (not 2, it's important). I created this Dokefile:

FROM prefecthq/prefect:3-latest

	WORKDIR /app

	CMD ["prefect", "server", "start", "--host", "0.0.0.0"]

I build the image and ran it with:

docker build -t prefect-server .

	docker run -d -p 4200:4200 --name prefect-server prefect-server

Then I access the GIU with: http://localhost:4200 Everything works. Now I want to create a work pool, start an agent and do a deploy. The target is to create a deploy file that run the Dockerimage that run the prefect-test.py file. I create the work pool with:

prefect work-pool create --type docker my-work-pool

I started a worker:

prefect worker start --pool docker my-work-pool

Now I have to define the deployment. I created a file named deploy_buy.py in a different folder than the root where I have the Dockerfile and prefect-test.py file:

from prefect import flow

	@flow(log_prints=True)
	def buy():
		print("Selling securities")

	if __name__ == "__main__":
		buy.deploy(
			name="my-deployment",
			work_pool_name="my-work-pool",
			image="docker.io/xxx/image"
		)

I copied it from official doc here: [https://docs.prefect.io/v3/deploy/infrastructure-examples/docker][1] [1]: https://docs.prefect.io/v3/deploy/infrastructure-examples/docker If I run the task, I see the message "Buying securities" in logs and at the end I see: Finished in state Completed() Process for flow run 'xxx' exited cleanly. But the file prefect-test.py wasn't invoked, because I don't see any other log. I used a different folder for deploy file because, if I don't do that, when I run deploy, it gives me an error saying that a Dockerfile is already in that folder. Executing in a different folder, it creates automatically a Dockerfile with this:

FROM prefecthq/prefect:3.1.4-python3.10
COPY . /opt/prefect/deploy/
WORKDIR /opt/prefect/deploy/

This is not clear, because that file doesn't contain anything about how to run my prefect-test.py file. For this reason I created another deploy file in the root of my project with this:

from prefect import flow
    from prefect.docker import DockerImage

    @flow(log_prints=True)
    def buy():
        print("Selling securities")

    if __name__ == "__main__":
        buy.deploy(
            name="my-deployment",
            work_pool_name="my-work-pool",
            image=DockerImage(
                name="docker.io/xxx/image",
                dockerfile="Dockerfile"
            ),
            push=False
        )

I used dockerfile="Dockerfile" because I want Prefect to use my Dockerfile. If I remove that line and try to make a deploy, as I wrote above, Prefect tells me that I already have a Dockerfile in that folder. With that line, I get no error. I don't want prefect create another build and push it, but I want it uses the image I already have on dockerhub. For this reason I put also:

push=False

If I deploy it and run the task, I get error:

Flow could not be retrieved from deployment.
	Traceback (most recent call last):
	File "<frozen importlib._bootstrap_external>", line 850, in exec_module
	File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
	File "deploy.py", line 2, in <module>
	from prefect.docker import DockerImage
	ImportError: cannot import name 'DockerImage' from 'prefect.utilities.dockerutils' (/usr/local/lib/python3.9/site-packages/prefect/utilities/dockerutils.py)

The above exception was the direct cause of the following exception:
...
prefect.exceptions.ScriptError: Script at 'deploy.py' encountered an exception: ImportError("cannot import name 'DockerImage' from 'prefect.utilities.dockerutils' (/usr/local/lib/python3.9/site-packages/prefect/utilities/dockerutils.py)")

This is strange because that import is the same of the one in the example on Prefect v3 docs. Any ideas? Thanks

hi @Luca Marantelli! thanks! ill follow up in github 🙂

Thanks!

Hi @Luca Marantelli, I have exactly same problem as this, but when the flow completed, I can not find the text written in my local machine. Where am I wrong in setting up this? Did you set the volume in the docker pool in prefect? Any clue is much appreciated!

Hi Vu. Sorry but i have completely abandoned Prefect. It's too hard to build what i need with it