Hello, I'm having some trouble with prefect agent when starting task. I don't really know why this error suddenly occurred, my flow used to work fine and I made some changes on my flow but not on the RunConf...

[2021-04-26 09:20:28,684] INFO - fargate-launch | Found 1 flow run(s) to submit for execution.
[2021-04-26 09:20:31,589] INFO - fargate-launch | Deploying flow run '6021f038-6c79-4e78-862a-e29143f7d205'
[2021-04-26 09:20:31,590] ERROR - fargate-launch | Logging platform error for flow run 6021f038-6c79-4e78-862a-e29143f7d205
[2021-04-26 09:20:34,079] ERROR - fargate-launch | Error while deploying flow
Traceback (most recent call last):
  File "/home/ubuntu/.local/lib/python3.8/site-packages/prefect/agent/agent.py", line 414, in deploy_and_update_flow_run
    deployment_info = self.deploy_flow(flow_run)
  File "/home/ubuntu/.local/lib/python3.8/site-packages/prefect/agent/ecs/agent.py", line 296, in deploy_flow
    taskdef = self.generate_task_definition(flow_run, run_config)
  File "/home/ubuntu/.local/lib/python3.8/site-packages/prefect/agent/ecs/agent.py", line 370, in generate_task_definition
    taskdef["family"] = f"prefect-{slug}"
TypeError: 'str' object does not support item assignment

Do you have any idea ? I didn't try to restart the agent, because I want to find the reason of this failure without resolving it just with a restart. Thanks !

Hi @Baptiste M! Just a friendly reminder to move the log into the thread next time to not crowd the Slack channel. I believe you need to remove the “f” from f”`prefect-{slug}"`. You can’t use f-strings with templating.

Oh sorry about the log... Hum I would like to remove the f, but it's not my code... This code come from prefect/agent/ecs/agent.py which is yours

Oh I see. My bad. I’ll look into it more.

I found something. I had the following line on my ECSRun config.

RUN_CONFIG = ECSRun(
    task_definition="prefect-importrawdataflow",
...
)

I removed the "prefect-" and now it works... But I don't know why. I use the same image to register the flow and to execute the flow. With a prefect 0.14.15 installed

I think task_definition should be a Dict of the task parameters (cpu, memory, networkMode, executionroleARN)

Yes

RUN_CONFIG = ECSRun(
    labels=["s3-flow-storage"],
    task_role_arn=TASK_ARN,
    image="******.<http://dkr.ecr.eu-west-3.amazonaws.com/*****|dkr.ecr.eu-west-3.amazonaws.com/*****>",
    run_task_kwargs=RUN_TASK_KWARGS,
    task_definition="importrawdataflow",
    execution_role_arn="arn:aws:iam::*****:role/ECSTasksAllowS3AndECR",
    cpu="2 vcpu",
    memory="4 GB"
)

The task_definition should be a dictionary that looks like this . Maybe you can try

task_definition={"containerDefinitions":[{"name": "importrawdataflow"}]}

Hum ok I see. I will try this. Thanks for your help !

Here is their definition . You can try running that to get the format you want. No problem!