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Dev Dasgupta

01/31/2022, 5:13 PM

Hi All, I'm new to prefect and after making a few refactoring to my existing flow.py. Initially, the folder structure looked the following and it was getting registered successfully (

prefect register --project my_project -p bar

)

foo_root_folder
├── README.md
├── bar
│   └── flow.py
├── pyproject.toml
├── requirements.txt
├── setup.cfg

Since the file

flow.py

was cluttered with all utils functions required for the flow execution I refactored it into a separate python package and made calls to those functions in

flow.py

from bar.utils import get_some_useful_function

The resultant folder looked like the following:

foo_root_folder
├── README.md
├── bar
│   ├── __init__.py
│   ├── utils.py
│   └── flow.py
├── pyproject.toml
├── requirements.txt
├── setup.cfg

When I try to register now I am getting error as

ModuleNotFoundError: No module named 'bar'

Can anyone please let me know if anyone faced similar issues before and how they resolved it? Thanks

2 replies · 2 participants

Andrew Lawlor

01/31/2022, 5:38 PM

im trying out prefect for our etl pipelines. we use GCP as our cloud provider. Id like to use prefect cloud and run agents in GCP. is the best option for doing this the vertex agent? If I do use that, what is the process for getting started? do i just create the agents at the beginning via cli and then leave them running, or do i have to continuously update them? is there a way to set up ci/cd for my flow code?

108 replies · 3 participants

Keith Veleba

01/31/2022, 5:53 PM

Does anyone know how to run an AWS batch job and wait for completion?

13 replies · 2 participants

David Yang

01/31/2022, 6:46 PM

Hi All, anyone can get flows from Azure DevOps service successfully using git storage? I got this error "Failed to load and execute Flow's environment: HTTPUnauthorized('No valid credentials provided')". It seems that git storage doesn't support private access token to access azure devops? This is my code: flow.storage = Git( repo="xxxxxxx/prefect/_git/prefect", # name of repo flow_path ="./flows/azuredevops.py", # location of flow file in repo branch_name ="main", repo_host="xxxxx@dev.azure.com", # repo host name git_token_secret_name ="azuresecret" )

14 replies · 3 participants

Keith Veleba

01/31/2022, 7:16 PM

when you put AWS_CREDENTIALS in via the UI as a Secret, do you use the text or the json options, and do you put it in as a JSON snippet?

22 replies · 3 participants

Chris Hemphill

01/31/2022, 8:05 PM

Hey everyone! Chris Hemphill from Actium Health

👋 5

4 replies · 4 participants

Dave

01/31/2022, 8:21 PM

Hi team, our team has recently deployed prefect on gcp kubernete. and it keeps saying

Couldn't connect to *Prefect Server* at *<http://34.82.119.23:4200/graphql>

,* can anyone help?

106 replies · 5 participants

Leon Kozlowski

01/31/2022, 9:10 PM

What will happen if I deploy a new version of a flow while a previous version is in a running state?

6 replies · 2 participants

Daniel Kornhauser

01/31/2022, 10:26 PM

Can anybody point to a relatively large project that uses prefect in github to checkout their directory tree structure ? Wondering how they group and name the python files of their flows and tasks when they have a lot of them.

5 replies · 2 participants

Yorrick Mendes

01/31/2022, 10:34 PM

Hey prefectors, I’ve got a rather basic question. Is it possible to add 2 flows as tasks/dependencies to a main flow? It doesn’t look like it’s possible besides unpacking each flow and adding all the tasks and dependencies individually. The other way to go about it would be to add two tasks that each run a flow locally but that doesn’t seem like the cleanest solution and I’d probably lose a lot of the UI sugar with that approach

2 replies · 2 participants

Suresh R

02/01/2022, 7:40 AM

Hi! Each mapped task is getting executed twice in my flow, What might be the reason?

INFO
CloudTaskRunner
Task 'collate-quarterly-crdlotcookie[5]': Starting task run...
INFO
CloudTaskRunner
Task 'collate-quarterly-crdlotcookie[5]': Starting task run...

8 replies · 2 participants

Vinoth Kumar

02/01/2022, 8:03 AM

Hi unable to install prefect Orion . I am getting ImportError: cannot import name 'ThreadedChildWatcher' from 'asyncio'

31 replies · 2 participants

Tony Waddle

02/01/2022, 12:03 PM

Sorry if I'm missing something obvious - how do you cancel a running agent? Can't see it in docs, -h or ui

3 replies · 2 participants

Muddassir Shaikh

02/01/2022, 12:31 PM

The slack alerts sent by state handlers

handler = slack_notifier(only_states=[Failed])

do not contain details of the flow name and the taskname, how can we add that?

2 replies · 2 participants

Konstantin

02/01/2022, 12:41 PM

Hello everyone, I can't figure out how to use native libraries in Prefect, for example "prefect.tasks.gsheets"
Give an example of the code for using this class

26 replies · 2 participants

Muddassir Shaikh

02/01/2022, 12:54 PM

The search bar is not able to find the taskname when the task name are created from a function. Example: PREFECT_SPLIT_FILES..... is a taskname but when searched doesn't appear. Does it have something to do with task_name and task_run_name ?

26 replies · 4 participants

Madhup Sukoon

02/01/2022, 1:57 PM

Hello! I am extremely new to Prefect, so apologies if this is a rookie question or has already been answered. I have a repository containing a bunch of scripts, folders and modules. I want to import a subset of the functions defined here and build a Flow in a new

flow.py

file and then run it via a Docker Agent. I also have some external (pip-installable) dependencies that would need to be present for the flow to run. Is it possible to do this? Does someone have an example Flow that uses Github Storage and Docker Run?

14 replies · 3 participants

Vladimir Bolshakov

02/01/2022, 2:09 PM

Hi! Is it possible to customise base URL of Orion UI in static builds? I have started standalone Orion server (without agent) and UI is not refreshed, because of CORS errors. UI app try to fetch data from

localhost:4200

. I think the reason is here: https://github.com/PrefectHQ/prefect/blob/orion/orion-ui/src/plugins/api.ts#L198

3 replies · 2 participants

Madhup Sukoon

02/01/2022, 5:24 PM

Hi! Just wondering if it's possible (maybe using

env

host_config

) to have the Docker Agent install packages in the docker container at runtime? (Looking for something similar to Docker Storage's

python_dependencies

, but for runtime)

4 replies · 2 participants

Constantino Schillebeeckx

02/01/2022, 5:44 PM

I've got a question about the ECS Agent documentation, in this section, there is a "Agent role policy" example, but there is no mention (I think) of where that gets used. The documentation only goes through the "execution role" and the "task role", where does "agent role" come into play?

12 replies · 3 participants

Madhup Sukoon

02/01/2022, 6:16 PM

I am using Prefect Cloud. My task Goes to

Scheduled

Submitted

and then nothing happens. The only entry in logs is:

Submitted for execution: Container ID: 143cabe06c721.....

My flow uses GitHub Storage and DockerRun, and uses some secrets. Any way I could get more verbose logs on what might be happening? This is what my

flow.py

looks like:

from main import planner, creator, publisher

planner = task(planner)
creator = task(creator)
publisher = task(publisher)

foo = Secret('foo')
bar = Secret('bar')

with Flow(
    "myflow",
    run_config = DockerRun(
        env={"EXTRA_PIP_PACKAGES": "requests pyyaml"}
    ),
    storage = GitHub(
        repo="me/myrepo",
        path="flow.py",
        access_token_secret="GITHUB_ACCESS_TOKEN"
    )
    
) as flow:
    plan = planner()
    media = creator(foo, bar, plan)
    post = publisher(foo, bar, media)

main

is an adjacent python file (

main.py

)

56 replies · 3 participants

Davoud Hejazi

02/01/2022, 9:22 PM

I want to add slack notifications in case there is an error while running the flow. I have the lines below as part of my code:

from prefect.utilities.notifications import slack_notifier
from prefect.engine.state import Failed
SLACK_WEBHOOK_URL = "the slack secret webhook url"
# os.environ["PREFECT__CONTEXT__SECRETS__SLACK_WEBHOOK_URL"] = "<https://hooks.slack.com/services/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>"
handler = slack_notifier(only_states=[Failed])
prefect.context.setdefault("secrets", {})
prefect.context.secrets["SLACK_WEBHOOK_URL"] = "the slack secret webhook url"

I have even created config.toml file in .predict directory with the content below:

[context.secrets]
SLACK_WEBHOOK_URL = "the slack secret webhook url"

My task stats with:

@task(nout=2, max_retries=1, retry_delay=timedelta(seconds=1), checkpoint=False, state_handlers=[handler])

I also tried to add prefect app to slack. But when running my flows I am seeing this error (part of the error): see thread To make it clear, when I remove the

state_handlers=[handler]

from my task definition the flow runs fine. When I visit the prefect app in slack I see this too, which I am not sure if it connected to my problem or not. Any comments on how I can solve the slack notification problem?

46 replies · 2 participants

Kevin Mullins

02/01/2022, 10:33 PM

Any advice on how to troubleshoot a job being scheduled but not submitted to Kubernetes? I have Prefect Core 0.15.11 with the agent installed in k8s. I ran a first flow which is running still, and then triggered a separate flow that got scheduled in the prefect UI but not submitted to K8S. I don’t say any logs from the agent saying it is deploying the flow run with that ID.

9 replies · 2 participants

Shaoyi Zhang

02/01/2022, 11:49 PM

Is there a timeout for submitted flow runs with Kubernetes agent when there’s not enough resources in the k8s namespace?

6 replies · 3 participants

Horatiu Bota

02/02/2022, 8:37 AM

hi community & thanks for the help! i've got a parameters json file that i want to pass to a prefect flow using

flow.run(parameters=json.loads(open(file).read()))

-- the parameters file looks something like this:

{
    "other_params": {},
    "company_params": {
        "company_id": "ID1",
        "company_name": "Company",
        "datasets": [
            {
                "dataset_label": "label",
                "dataset_url": "URL"
            },
        ]
    }
}

is there any way to access nested values in the actual flow? something like:

with Flow("flow") as flow:
        company_params = Parameter("company_params")
        datasets = company_params.get("datasets")

1 reply · 2 participants

Suresh R

02/02/2022, 10:45 AM

Hi!, I have a mapped task with 21 childs, also set task concurrency of 5, But only 2 child tasks are scheduled at a time, What might be the cause?

35 replies · 3 participants

Chris Arderne

02/02/2022, 12:09 PM

@task

decorator has

log_stdout=True

but is there any way to add

stderr

to logging?

41 replies · 3 participants

shijas km

02/02/2022, 2:50 PM

Hi I am facing an issue I need to add a shell task before my python tasks in a flow but its not working , throwing some error like flow outside cant be called but when i comment out all task except the shell task it works can I combine both shell task and python task in a single flow? any example??

9 replies · 3 participants

Constantino Schillebeeckx

02/02/2022, 3:36 PM

is there some sort of API endpoint that we can hit which serves as a health check? I'm wondering how I can programmatically check that the agent is healthy

17 replies · 4 participants

David Wang

02/02/2022, 4:02 PM

Hi everyone, I am currently trying to setup an ECS agent with aws. However, the task seems to stop and exit with the error

essential container in task exited

. The prefect ecs agent also does not appear in the UI. I have been able to start the ECS agent locally, but am unable to start it through aws. Another thing to mention is that when I try to add the logConfiguration to try to see what could be going wrong with the service it will give me an error of

ResourceInitializationError: failed to validate logger args: : signal: killed

. I’ve double checked with devOps that the IAM roles and network configurations should be correct too. Any ideas on how to debug this or why this is happening?

41 replies · 4 participants

Title

David Wang

02/02/2022, 4:02 PM

Hi everyone, I am currently trying to setup an ECS agent with aws. However, the task seems to stop and exit with the error

essential container in task exited

ResourceInitializationError: failed to validate logger args: : signal: killed

. I’ve double checked with devOps that the IAM roles and network configurations should be correct too. Any ideas on how to debug this or why this is happening?

Kevin Kho

02/02/2022, 4:05 PM

First time I have seen the

ResourceInitializationError

myself. Are you using the base Prefect image or your own? Are you just following the docs or do you have any added configuration?

David Wang

02/02/2022, 4:06 PM

I followed the docs and the tutorial at https://towardsdatascience.com/how-to-cut-your-aws-ecs-costs-with-fargate-spot-and-prefect-1a1ba5d2e2df

only difference I made was not using the aws parameter store for now

Kevin Kho

02/02/2022, 4:15 PM

I think we need the logging to figure out the ECS issue and it might be a connectivity issue or the log group doesn’t exist so I would check for those?

David Wang

02/02/2022, 4:29 PM

I’ve confirmed that the log group exists. I did ask devOps about the connectivity earlier, but they said that I shouldnt be having trouble connecting to CloudWatch. I will try asking again about it though

Kevin Kho

02/02/2022, 4:31 PM

The most common cause for the container exiting though is image incompatibility.

David Wang

02/02/2022, 4:32 PM

current image that is specified in the container definitions is

"image": "prefecthq/prefect:latest-python3.8",

Kevin Kho

02/02/2022, 4:34 PM

Ah ok that should be good

David Wang

02/02/2022, 10:20 PM

I talked to devOps and they confirmed that connectivity is not the problem, as there would be a different error message. I also rechecked the log configuration but there doesn’t seem to be anything wrong.

"logConfiguration": {
                "logDriver": "awslogs",
                "options": {
                    "awslogs-group": "$ECS_LOG_GROUP_NAME",
                    "awslogs-region": "$AWS_REGION",
                    "awslogs-stream-prefix": "ecs",
                    "awslogs-create-group": "true"
                }
            }

is there any other way to add the logs to the task definition like in the aws console?

Kevin Kho

02/02/2022, 10:23 PM

Not quite cuz the Task Definition tab just gives an error but no logs if you don’t setup CloudWatch. It won’t fix your logging issue, but the

task exited

can also be due to a lack of IAM permissions

Like not able to pull the image

David Wang

02/07/2022, 4:21 PM

I did once get a

CannotPullContainerError: inspect image has been retried 5 time(s): failed to resolve ref "<http://docker.io/prefecthq/prefect:latest-python3.8|docker.io/prefecthq/prefect:latest-python3.8>": failed to do request: Head <https://registry-1.docker.io/v2/prefecthq/prefect/manifests/latest-python3.8>: dial tcp ...

error while I was messing around with the security groups

I did also double check the IAM permissions and I should have the correct permissionss

Anna Geller

02/07/2022, 5:08 PM

it looks like this setting might be missing:

assignPublicIp=ENABLED

You can set up as part of the network configuration:

aws ecs create-service \
    --service-name $ECS_SERVICE_NAME\
    --task-definition $ECS_SERVICE_NAME:1 \
    --desired-count 1 \
    --launch-type FARGATE \
    --platform-version LATEST \
    --cluster $ECS_CLUSTER_NAME \
    --network-configuration awsvpcConfiguration="{subnets=[$SUBNET1, $SUBNET2, $SUBNET3],assignPublicIp=ENABLED}" --region $AWS_REGION

To explain it a bit more - my intuition (not 100% sure) is that your flow run container doesn't have access to the Internet in order to pull the container image from Dockerhub

David Wang

02/07/2022, 6:50 PM

I do have that setting enabled, however the VPC and subnets I’m using is not a default subnet, nor does it allow auto-assign public ipv4 or 6 addresses - would that affect it?

the VPC and subnet does have internet connection through a NAT gateway

Anna Geller

02/07/2022, 6:57 PM

that may be the issue indeed since you need to make sure that the CONTAINER within that instance also has access to the internet through that NAT gateway, You can test this out by launching a simple ECS task with a container getting the image from some public Dockerhub repo. Have you tried launching any ECS task within that container without Prefect? Did that work using the same network configuration?

David Wang

02/07/2022, 6:59 PM

I have not launched any task without prefect - is there any simple ecs task I can run to test this out?

Anna Geller

02/07/2022, 7:04 PM

there are a bunch of tutorials online, here are some you can use: •

https://www.youtube.com/watch?v=o_qSS4S1g34▾

•

https://www.youtube.com/watch?v=eq4wL2MiNqo▾

• https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ECS_AWSCLI_Fargate.html • https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs-cli-tutorial-ec2.html

David Wang

02/07/2022, 9:06 PM

just tested out launching an ecs task using the aws docs tutorial, and it was able to run with no problems

Anna Geller

02/08/2022, 2:43 PM

Did you run it in the same subnets as your Perfect flows? Did you assign public IPs? Did the setup for this differ in any way from your Prefect ECSRun?

David Wang

02/08/2022, 4:08 PM

Yes, I ran it in the same subnets as the prefect flows. I don’t think I assigned public IPs as I followed the part of the tutorial where the example was using a private subnet. I also reran the prefect flows with the exact same command as the tutorial besides the task definition name and it returned the

ResourceInitializationError: failed to validate logger args: : signal: killed

error again. And even if I remove the log configuration part to see if it will run it will give the

essential container in task exited

Kevin Kho

02/08/2022, 4:25 PM

Hey David, unfortunately I think there isn’t more advice we can give without really going into the AWS account and looking at the setup. We don’t offer that here in community support, but can always connect you to Prefect’s professional services team.

Or I dunno if Anna may have more ideas. She’s out sick though for now. Sorry about that.

David Wang

02/08/2022, 10:33 PM

I finally got it the logs to work - turns out I had to delete an existing log endpoint. DevOps had not tried this because he did not think that was the problem. So now the ECS agent shows up in the UI and is up and running. Only problem now is that when I try to run an example flow like this it gives me an error of

Parameter validation failed: Missing required parameter in networkConfiguration.awsvpcConfiguration: "subnets" Unknown parameter in networkConfiguration.awsvpcConfiguration: "Subnets", must be one of: subnets, securityGroups, assignPublicIp

. Do I need to specify network configurations again somewhere in the run config?

Kevin Kho

02/08/2022, 11:09 PM

Glad you got that figured out. So this error is because Prefect can infer the default VPC, but if you have custom ones, you need to specify them with a job template. It seems like your agent was able to start though? How did you start your agent in the right VPC?

David Wang

02/09/2022, 4:19 PM

i got it to run by adding the --run-task-kwargs command in the task definition like in this post

Kevin Kho

02/09/2022, 4:24 PM

So agent works but Flow still does not?

David Wang

02/09/2022, 4:24 PM

yes thats correct

Kevin Kho

02/09/2022, 4:31 PM

So I think there are two places to put this. One is on the flow like this where you add a

task_definition_path

. That links to here , and then you can specify those subnet and security group there. The ECS agent also takes a definition upon starting . You can pass

--task_definition_path

. You just need to make sure that these live somewhere the agent can pull during runtime (like an S3 bucket it has access to). The agent task_definition serves as a default for the Flows that it runs, but the RunConfig can override it. The default one the agent uses can be found here

David Wang

02/09/2022, 8:10 PM

what would be the correct format to specify the subnets and security groups? This is what I currently have but it says networkConfiguration parameter doesn’t exist.

networkMode: awsvpc
cpu: 512
memory: 1024
containerDefinitions:
  - name: prefectEcsAgent
networkConfiguration:
  awsvpcConfiguration:
    Subnets:
      - subnet-xxx
    securityGroups:
      - sg-xxx
    assignPublicIp: DISABLED

Kevin Kho

02/09/2022, 8:21 PM

Let me look around. The quickest I found is this

Got my ECS set up. About to try this

Ok I think my understanding was wrong. Per the AWS ECS here , you need to specify it at run time instead of the task definition that gets registered. So custom VPCs need to be specified in task definition

run_task_kwargs

or on the agent

If you specify the awsvpc network mode, the task is allocated an elastic network interface, and you must specify a NetworkConfiguration when you create a service or run a task with the task definition.

This is so painful I dunno why you can’t do it as part of the task definition

David Wang

02/09/2022, 10:17 PM

Yep it works after I specified the subnets and security group inside the run_task_kwargs argument in the runConfig for the flow. Interesting that I have to since I already specified the subnets/security groups with the run_task_kwargs parameter when starting the agent.

Kevin Kho

02/09/2022, 10:22 PM

The kwargs on the agent should propagate. Could you share your syntax?

David Wang

02/10/2022, 3:57 PM

{
  "family": "$ECS_SERVICE_NAME",
  "requiresCompatibilities": [
    "FARGATE"
  ],
  "networkMode": "awsvpc",
  "cpu": "512",
  "memory": "1024",
  "taskRoleArn": "arn:aws:iam::xxx:role/prefectTaskRole",
  "executionRoleArn": "arn:aws:iam::xxx:role/prefectECSAgentTaskExecutionRole",
  "containerDefinitions": [
    {
      "name": "$ECS_SERVICE_NAME",
      "image": "prefecthq/prefect",
      "essential": true,
      "command": [
        "prefect",
        "agent",
        "ecs",
        "start",
        "--run-task-kwargs",
        "<s3://xxx-test-bucket/david/ecs-config.yaml>"
      ],
      "environment": [
        {
          "name": "PREFECT__CLOUD__API_KEY",
          "value": "xxx"
        },
        {
          "name": "PREFECT__CLOUD__AGENT__LABELS",
          "value": "['dev']"
        },
        {
          "name": "PREFECT__CLOUD__AGENT__LEVEL",
          "value": "INFO"
        },
        {
          "name": "PREFECT__CLOUD__API",
          "value": "<https://api.prefect.io>"
        }
      ],
      "logConfiguration": {
        "logDriver": "awslogs",
        "options": {
          "awslogs-group": "$ECS_LOG_GROUP_NAME",
          "awslogs-region": "$AWS_REGION",
          "awslogs-stream-prefix": "ecs",
          "awslogs-create-group": "true"
        }
      }
    }
  ]
}

and inside the yaml file

networkConfiguration:
  awsvpcConfiguration:
    Subnets:
      - subnet-xxx
    securityGroups:
      - sg-xxx
    assignPublicIp: DISABLED

I also have the network configuration setup when creating the service with aws ecs create-service

aws ecs create-service \
    --service-name $ECS_SERVICE_NAME\
    --task-definition $ECS_SERVICE_NAME:1 \
    --desired-count 1 \
    --launch-type FARGATE \
    --cluster $ECS_CLUSTER_NAME \
    --network-configuration awsvpcConfiguration="{subnets=[$SUBNET1],securityGroups=[$SECURITYGROUP]}" --region $AWS_REGION

To get the flow to run I just put in the networkConfiguration parameter in the RUN_CONFIG

RUN_CONFIG = ECSRun(
    labels=["dev"],
    task_role_arn="arn:aws:iam::xxx:role/prefectTaskRole",
    run_task_kwargs=dict(cluster="prefectEcsCluster",networkConfiguration={
            'awsvpcConfiguration': {
                'subnets': [
                    'subnet-xxx'
                ],
                'securityGroups': [
                    'sg-xxx',
                ],
                'assignPublicIp': 'DISABLED'
            }
        }),
)

Christopher

02/11/2022, 6:53 AM

This might be unhelpful advice at this stage but I was reading through trying to get my own ECS set up. Your yaml file has "Subnets" with a capital S which I think is wrong. That what this error message is saying anyway: https://prefect-community.slack.com/archives/CL09KU1K7/p1644359607318099?thread_ts=1643817770.525689&cid=CL09KU1K7

:upvote: 3

David Wang

02/11/2022, 4:28 PM

Looks like you were right! The flow now works normally without any extra added networkConfigurations needed.

🙌 1

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