<@ULVA73B9P> help me to figure out why my ecs work...
# ask-marvinm
Madushan Pathirana
10/01/2025, 9:46 AM@Marvin help me to figure out why my ecs worker is crashing
logs
Worker 'ECSWorker fc26a074-0965-4fe3-9154-da6afb536aa1' submitting flow run '6b23bf36-6cef-4d26-823a-ec47b7ad927a'
031249 PM
prefect.flow_runs.worker
Retrieving ECS task definition 'arnawsecsap southeast 1010614160260task definition/data science prefect sync11'...
031249 PM
prefect.flow_runs.worker
Skipping task definition construction since a task definition ARN is provided.
031249 PM
prefect.flow_runs.worker
The following job variable references in the task definition template will be ignored: cpu, container_name, memory, image, family
031249 PM
prefect.flow_runs.worker
Using ECS task definition 'arnawsecsap southeast 1010614160260task definition/data science prefect sync11'...
031249 PM
prefect.flow_runs.worker
Creating ECS task run...
031249 PM
prefect.flow_runs.worker
Waiting for ECS task run to start...
031250 PM
prefect.flow_runs.worker
ECS task status is PROVISIONING.
031250 PM
prefect.flow_runs.worker
ECS task status is PENDING.
031305 PM
prefect.flow_runs.worker
ECS task status is RUNNING.
031325 PM
prefect.flow_runs.worker
Completed submission of flow run '6b23bf36-6cef-4d26-823a-ec47b7ad927a'
031330 PM
prefect.flow_runs.worker
ECS task status is DEPROVISIONING.
031340 PM
prefect.flow_runs.worker
ECS task status is STOPPED.
031355 PM
prefect.flow_runs.worker
Container 'data-science-prefect-sync' exited with non-zero exit code 2.
031355 PM
prefect.flow_runs.worker
Reported flow run '6b23bf36-6cef-4d26-823a-ec47b7ad927a' as crashed: Flow run infrastructure exited with non-zero status code 2.
031355 PM
prefect.flow_runs.worke
m
Marvin
10/01/2025, 9:46 AM✅ thought for 551.2 seconds
Marvin
10/01/2025, 9:55 AMThanks for sharing the logs — those are helpful. Exit code 2 from an ECS container usually means “bad CLI usage” (argparse error) or an entrypoint/command mismatch, not a crash inside Python. Given your setup and the messages in the worker logs, here are the top suspects and how to fix them.
What Prefect runs in the ECS container
- In Prefect 3.x, the worker starts your run by executing:
-
prefect flow-run execute --flow-run-id <id> Copy code
FROM python:3.11-slim
RUN pip install --no-cache-dir "prefect>=3" "prefect-aws"
ENTRYPOINT [] Copy code
docker run --rm <your-image> prefect --version
docker run --rm <your-image> prefect flow-run execute --helpPREFECT_API_URLPREFECT_API_KEYstream_task_logs: trueMarvin
10/01/2025, 9:55 AM- ECS task IAM: Attach AmazonECSTaskExecutionRolePolicy so it can pull the image and write logs.
- Networking:
- ECS container instances security group allows egress to the Prefect EC2 host on 4200.
- Prefect EC2 host security group allows ingress from the ECS task ENIs on port 4200.
-
PREFECT_API_URL=http://<prefect-ec2-private-ip>:4200/apistream_task_logstask_definition_arnPREFECT_API_URLm
Madushan Pathirana
10/01/2025, 9:59 AM@Marvin logs from the container
October 2025, 15:26╭─ Commands ───────────────────────────────────────────────────────────────────╮1 October 2025, 15:26│ version Get the current Prefect version and integration │1 October 2025, 15:26│ information. │1 October 2025, 15:26│ init Initialize a new deployment configuration recipe. │1 October 2025, 15:26│ deploy Create a deployment to deploy a flow from this │1 October 2025, 15:26│ project. │1 October 2025, 15:26│ transfer Transfer resources from one Prefect profile to │1 October 2025, 15:26│ another. │1 October 2025, 15:26│ artifact Inspect and delete artifacts. │1 October 2025, 15:26│ block Manage blocks. │1 October 2025, 15:26│ cloud Authenticate and interact with Prefect Cloud │1 October 2025, 15:26│ shell Serve and watch shell commands as Prefect flows. │1 October 2025, 15:26│ concurrency-limit Manage task-level concurrency limits. │1 October 2025, 15:26│ config View and set Prefect profiles. │1 October 2025, 15:26│ dashboard Commands for interacting with the Prefect UI. │1 October 2025, 15:26│ deployment Manage deployments. │1 October 2025, 15:26│ dev Internal Prefect development. │1 October 2025, 15:26│ events Stream events. │1 October 2025, 15:26│ flow View and serve flows. │1 October 2025, 15:26│ flow-run Interact with flow runs. │1 October 2025, 15:26│ global-concurrency-limit Manage global concurrency limits. │1 October 2025, 15:26│ profile Select and manage Prefect profiles. │1 October 2025, 15:26│ server Start a Prefect server instance and interact with │1 October 2025, 15:26│ the database │1 October 2025, 15:26│ task Work with task scheduling. │1 October 2025, 15:26│ variable Manage variables. │1 October 2025, 15:26│ work-pool Manage work pools. │1 October 2025, 15:26│ work-queue Manage work queues. │1 October 2025, 15:26│ worker Start and interact with workers. │1 October 2025, 15:26│ task-run View and inspect task runs. │1 October 2025, 15:26│ automation Manage automations. │1 October 2025, 15:26╰──────────────────────────────────────────────────────────────────────────────╯1 October 2025, 15:26╭─ Options ────────────────────────────────────────────────────────────────────╮1 October 2025, 15:26│ --version -v Display the current version. │1 October 2025, 15:26│ --profile -p TEXT Select a profile for this CLI │1 October 2025, 15:26│ run. │1 October 2025, 15:26│ --prompt --no-prompt Force toggle prompts for this │1 October 2025, 15:26│ CLI run. │1 October 2025, 15:26│ [default: (from │1 October 2025, 15:26│ PREFECT_CLI_PROMPT)] │1 October 2025, 15:26│ --install-completion Install completion for the │1 October 2025, 15:26│ current shell. │1 October 2025, 15:26│ --show-completion Show completion for the │1 October 2025, 15:26│ current shell, to copy it or │1 October 2025, 15:26│ customize the installation. │1 October 2025, 15:26│ --help Show this message and exit. │1 October 2025, 15:26╰──────────────────────────────────────────────────────────────────────────────╯1 October 2025, 15:261 October 2025, 15:26Usage: prefect [OPTIONS] COMMAND [ARGS]...1 October 2025, 15:26m
Marvin
10/01/2025, 9:59 AMYour message was too long, here's your message at the allowed limit:
logs from the container
October 2025 15 26╭─ Commands ───────────────────────────────────────────────────────────────────╮1 October 2025 15 26│ version Get the current Prefect version and integration │1 October 2025 15 26│ information │1 October 2025 15 26│ init Initialize a new deployment configuration recipe │1 October 2025 15 26│ deploy Create a deployment to deploy a flow from this │1 October 2025 15 26│ project │1 October 2025 15 26│ transfer Transfer resources from one Prefect profile to │1 October 2025 15 26│ another │1 October 2025 15 26│ artifact Inspect and delete artifacts │1 October 2025 15 26│ block Manage blocks │1 October 2025 15 26│ cloud Authenticate and interact with Prefect Cloud │1 October 2025 15 26│ shell Serve and watch shell commands as Prefect flows │1 October 2025 15 26│ concurrency-limit Manage task-level concurrency limits │1 October 2025 15 26│ config View and set Prefect profiles │1 October 2025 15 26│ dashboard Commands for interacting with the Prefect UI │1 October 2025 15 26│ deployment Manage deployments │1 October 2025 15 26│ dev Internal Prefect development │1 October 2025 15 26│ events Stream events │1 October 2025 15 26│ flow View and serve flows │1 October 2025 15 26│ flow-run Interact with flow runs │1 October 2025 15 26│ global-concurrency-limit Manage global concurrency limits │1 October 2025 15 26│ profile Select and manage Prefect profiles │1 October 2025 15 26│ server Start a Prefect server instance and interact with │1 October 2025 15 26│ the database │1 October 2025 15 26│ task Work with task scheduling │1 October 2025 15 26│ variable Manage variables │1 October 2025 15 26│ work-pool Manage work pools │1 October 2025 15 26│ work-queue Manage work queues │1 October 2025 15 26│ worker Start and interact with workers │1 October 2025 15 26│ task-run View and inspect task runs │1 October 2025 15 26│ automation Manage automations │1 October 2025 15 26╰──────────────────────────────────────────────────────────────────────────────╯1 October 2025 15 26╭─ Options ────────────────────────────────────────────────────────────────────╮1 October 2025 15 26│ --version -v Display the current version │1 October 2025 15 26│ --profile -p TEXT Select a profile for this CLI │1 October 2025 15 26│ run │1 October 2025 15 26│ --prompt --no-prompt Force toggle prompts for this │1 October 2025 15 26│ CLI run │1 October 2025 15 26│ [default (from │1 October 2025 15 26m
Madushan Pathirana
10/01/2025, 11:06 AM@Marvin last few logs of the task
1 October 2025, 16:26│ --prompt --no-prompt Force toggle prompts for this │1 October 2025, 16:26│ CLI run. │1 October 2025, 16:26│ [default: (from │1 October 2025, 16:26│ PREFECT_CLI_PROMPT)] │1 October 2025, 16:26│ --install-completion Install completion for the │1 October 2025, 16:26│ current shell. │1 October 2025, 16:26│ --show-completion Show completion for the │1 October 2025, 16:26│ current shell, to copy it or │1 October 2025, 16:26│ customize the installation. │1 October 2025, 16:26│ --help Show this message and exit. │1 October 2025, 16:26╰──────────────────────────────────────────────────────────────────────────────╯1 October 2025, 16:261 October 2025, 16:26Usage: prefect [OPTIONS] COMMAND [ARGS]...1 October 2025, 16:26m
Marvin
10/01/2025, 11:06 AM✅ thought for 85.3 seconds
Marvin
10/01/2025, 11:08 AMThanks — those log lines are super telling. They’re the top-level Prefect CLI help, which means the container ended up running just
prefect Copy code
prefect flow-run execute --flow-run-id <id>cpumemoryimagefamilycontainer_name["/bin/sh","-c"]sh -c$0$1prefect Copy code
FROM python:3.11-slim
RUN pip install --no-cache-dir "prefect>=3" "prefect-aws"
# IMPORTANT: do not set a shell entrypoint; let Prefect pass the command
ENTRYPOINT []commandentryPoint Copy code
#!/usr/bin/env sh
set -e
# ... any setup you need ...
exec "$@" # This is critical: passes Prefect’s command through Copy code
COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]prefect Copy code
docker run --rm <your-image> prefect --version
docker run --rm <your-image> prefect flow-run execute --helpPREFECT_API_URLhttp://<prefect-ec2-private-ip>:4200/apiPREFECT_API_KEYcontainer_nameentryPointcommandlogConfigurationm
Madushan Pathirana
10/01/2025, 11:16 AM@Marvin this is my prefect server docker file which worked with ecs worker once
FROM prefecthq/prefect:3-python3.12
RUN apt-get update && apt-get install -y git curl && rm -rf /var/lib/apt/lists/*
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt asyncpg
ENTRYPOINT ["/opt/prefect/entrypoint.sh"]
i guess somthing wrong with the ecs worker pool advance settings
m
Marvin
10/01/2025, 11:16 AM✅ thought for 162.8 seconds
Marvin
10/01/2025, 11:19 AMThanks — that Dockerfile explains the behavior.
Your image inherits the official entrypoint:
Copy code
ENTRYPOINT ["/opt/prefect/entrypoint.sh"] Copy code
prefect flow-run execute --flow-run-id <id> Copy code
/opt/prefect/entrypoint.sh prefect flow-run execute ... Copy code
prefect prefect flow-run execute ... Copy code
FROM prefecthq/prefect:3-python3.12
RUN apt-get update && apt-get install -y git curl && rm -rf /var/lib/apt/lists/*
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt asyncpg
ENTRYPOINT [] Copy code
#!/usr/bin/env sh
set -e
exec "$@" Copy code
COPY forward-entrypoint.sh /forward-entrypoint.sh
RUN chmod +x /forward-entrypoint.sh
ENTRYPOINT ["/forward-entrypoint.sh"] Copy code
docker run --rm <your-image> prefect flow-run execute --help Copy code
docker run --rm --entrypoint "" <your-image> prefect flow-run execute --helphttp://<your-prefect-ec2-private-ip>:4200/apim
Madushan Pathirana
10/01/2025, 11:29 AM@Marvin Failed to submit flow run '131c7a14-9d53-4a47-b533-e23f564bfc4b' to infrastructure.
Traceback (most recent call last):
File "/usr/local/lib/python3.12/site-packages/prefect/workers/base.py", line 1281, in _submit_run_and_capture_errors
result = await self.run(
^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 723, in run
) = await run_sync_in_worker_thread(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect/utilities/asyncutils.py", line 233, in run_sync_in_worker_thread
result = await anyio.to_thread.run_sync(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/anyio/to_thread.py", line 56, in run_sync
return await get_async_backend().run_sync_in_worker_thread(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2476, in run_sync_in_worker_thread
return await future
^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 967, in run
result = context.run(func, *args)
^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect/utilities/asyncutils.py", line 243, in call_with_mark
return call()
^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 837, in _create_task_and_wait_for_start
task_run_request = self._prepare_task_run_request(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 1629, in _prepare_task_run_request
assert task_run_request["taskDefinition"] == task_definition_arn, (
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: Task definition ARN mismatch: None != 'arnawsecsap southeast 1010614160260task definition/prefect my ecs pool 8de3cc2c 4111 497d 9512 aa23f979fd7f1'
m
Marvin
10/01/2025, 11:29 AM✅ thought for 151.6 seconds
Marvin
10/01/2025, 11:32 AMThat stack trace pinpoints the issue: your ECS work pool’s Advanced “Task run request overrides” is clobbering the taskDefinition that Prefect sets.
What the error means
- Prefect prepared to run with task definition arn:
-
arn:aws:ecs:...:task-definition/prefect_my-ecs-pool_...:1taskDefinition=None"taskDefinition": nulloverridestaskDefinitionNonetaskDefinitionoverridesoverrides.containerOverrides[<target-container>].commandenvironmentoverrides Copy code
{
"capacityProviderStrategy": [
{
"capacityProvider": "YourEc2CapacityProvider",
"weight": 1
}
],
"enableExecuteCommand": true,
"propagateTags": "TASK_DEFINITION",
"tags": [
{
"key": "env",
"value": "dev"
}
]
}taskDefinitionclusternetworkConfiguration Copy code
prefect work-pool inspect "my-ecs-pool"task_definition_arntaskDefinitionoverridesprefecthq/prefect:3-python3.12ENTRYPOINT ["/opt/prefect/entrypoint.sh"]ENTRYPOINT []exec "$@"m
Madushan Pathirana
10/01/2025, 11:38 AM@Marvin for taskDefinition arn i shoudl set prefect worker task arn or prefect server arn
m
Marvin
10/01/2025, 11:38 AM✅ thought for 23.5 seconds
Marvin
10/01/2025, 11:39 AMUse the task definition ARN for the container that will run your flow code — not the Prefect Server and not the Prefect Worker.
Clarifying:
- Prefect Server runs on your EC2 host; it does not have an ECS task definition ARN.
- Your Prefect Worker (in your setup) is just a process on that same EC2 host; it also does not need an ECS task definition ARN.
- The ECS task definition ARN you provide in the ECS work pool is for the “flow runtime” container/image (e.g., based on prefecthq/prefect or your own image) that will execute:
Copy code
prefect flow-run execute --flow-run-id <id>exec "$@"PREFECT_API_URLhttp://<your-prefect-ec2-private-ip>:4200/apim
Madushan Pathirana
10/01/2025, 11:40 AM@Marvin my prefect server runs in ecs
m
Marvin
10/01/2025, 11:40 AM✅ thought for 42.2 seconds
Marvin
10/01/2025, 11:41 AMGot it — even if your Prefect Server is running in ECS, the ECS work pool should NOT use your Prefect Server’s task definition ARN.
Use a task definition ARN for the flow-runner container
- The ARN you put in the ECS work pool must point to a task definition built for running flow runs (i.e., a container image with Prefect installed that will execute “prefect flow-run execute …”).
- Do not use:
- The Prefect Server task definition ARN (that TD is for the API/UI services and will have an entrypoint/command to run the server, not flows)
- Any TD with a shell/entrypoint that hijacks the command
Recommended setup for a dedicated flow-run task definition
- Image: your own image or prefecthq/prefect:3-… with your deps installed
- ENTRYPOINT: empty or a forwarding wrapper
- In Dockerfile: ENTRYPOINT []
- Or in the ECS task definition container: set entryPoint: [] to override the image’s entrypoint
- Command: leave blank in the TD; Prefect will override with:
- prefect flow-run execute --flow-run-id <id>
- Logs: awslogs configured so logs are visible in CloudWatch (and streamable in Prefect)
- Roles: task execution role with logs/ECR permissions; task role for your RDS access, etc.
- Single container: prefer exactly one container in the TD so Prefect’s overrides target the right one
Minimal container section example
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{
"containerDefinitions": [
{
"name": "flow-runner",
"image": "<http://your-account.dkr.ecr.ap-southeast-1.amazonaws.com/your-prefect-image:latest|your-account.dkr.ecr.ap-southeast-1.amazonaws.com/your-prefect-image:latest>",
"essential": true,
"entryPoint": [], // critical: let Prefect’s command run verbatim
"command": [], // leave empty; Prefect will override
"logConfiguration": {
"logDriver": "awslogs",
"options": {
"awslogs-group": "/ecs/prefect/flows",
"awslogs-region": "ap-southeast-1",
"awslogs-stream-prefix": "flow"
}
}
}
],
"requiresCompatibilities": ["EC2"],
"networkMode": "awsvpc",
"cpu": "512",
"memory": "1024",
"executionRoleArn": "arn:aws:iam::<acct>:role/ecsTaskExecutionRole",
"taskRoleArn": "arn:aws:iam::<acct>:role/YourFlowTaskRole"
} Copy code
prefect work-pool inspect "<your-ecs-pool-name>"m
Madushan Pathirana
10/01/2025, 11:50 AM@Marvin I dont gget it , i have 2 arns, one for prefect server and prefect worker arn, what should i use for the task definition in the ecs worker pool configurations
m
Marvin
10/01/2025, 11:50 AM✅ thought for 18.3 seconds
Marvin
10/01/2025, 11:50 AMShort answer: neither. Do NOT use your Prefect Server ARN or your Prefect Worker ARN.
The ECS work pool’s task_definition_arn must point to a task definition built specifically for running flow runs (a “flow-runner” TD), not for running the server or the worker service.
Why:
- Server TD: its entrypoint/command starts the API/UI, not flows.
- Worker TD: its entrypoint/command starts the worker process, not flows.
- Flow-run TD: must allow Prefect to inject and run this command verbatim:
Copy code
prefect flow-run execute --flow-run-id <id>m
Madushan Pathirana
10/01/2025, 11:59 AM@Marvin write me a task definitions
m
Marvin
10/01/2025, 11:59 AM✅ thought for 115.9 seconds
Marvin
10/01/2025, 12:01 PMGreat — here’s a ready-to-use ECS task definition for your flow runs (EC2 launch type). It’s single-container, neutralizes the image entrypoint so Prefect can inject its command, and sets up CloudWatch logging in ap-southeast-1.
Replace the REPLACE_ME_ placeholders, then register it and use the returned ARN in your ECS work pool.
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{
"family": "prefect-flow-runner",
"networkMode": "awsvpc",
"requiresCompatibilities": ["EC2"],
"executionRoleArn": "arn:aws:iam::REPLACE_ME_AWS_ACCOUNT_ID:role/ecsTaskExecutionRole",
"taskRoleArn": "arn:aws:iam::REPLACE_ME_AWS_ACCOUNT_ID:role/YourFlowTaskRole",
"containerDefinitions": [
{
"name": "flow-runner",
"image": "REPLACE_ME_ECR_OR_DOCKER_IMAGE",
"essential": true,
"entryPoint": [],
"command": [],
"cpu": 256,
"memoryReservation": 512,
"logConfiguration": {
"logDriver": "awslogs",
"options": {
"awslogs-group": "/ecs/prefect/flows",
"awslogs-region": "ap-southeast-1",
"awslogs-stream-prefix": "flow"
}
},
"environment": [
// Leave Prefect env empty; the worker will inject PREFECT_API_URL (and API key if Cloud)
]
}
]
}m
Madushan Pathirana
10/01/2025, 12:08 PM@Marvin i am using data-science-prefect-sync:10 for prefect server task defition and i use data-science-prefect-sync:9 for Task Definition ARN in ecs worker pool configurations . and it work. both use same docker image which is below docekr file
FROM prefecthq/prefect:3-python3.12
RUN apt-get update && apt-get install -y git curl && rm -rf /var/lib/apt/lists/*
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt asyncpg
ENTRYPOINT ["/opt/prefect/entrypoint.sh"]
how did it work ?
m
Marvin
10/01/2025, 12:08 PM✅ thought for 114.0 seconds
Marvin
10/01/2025, 12:10 PMShort answer: it worked because the Prefect base image’s entrypoint is designed to run Prefect CLI commands, and the ECS worker successfully overrode the container command with the flow-run command.
What’s going on under the hood
- Your image uses the official entrypoint:
Copy code
ENTRYPOINT ["/opt/prefect/entrypoint.sh"]prefectprefectprefect Copy code
prefect flow-run execute --flow-run-id <id> Copy code
flow-run execute --flow-run-id <id> Copy code
prefect server start Copy code
prefect flow-run execute --flow-run-id <id>prefectcontainerOverrides.commandoverridescommandtaskDefinitionoverridescapacityProviderStrategy/bin/sh -cm
Madushan Pathirana
10/01/2025, 1:06 PM@Marvin
Failed to submit flow run 'c22efa13-bc4c-435b-8e83-49756d48fbca' to infrastructure.
Traceback (most recent call last):
File "/usr/local/lib/python3.12/site-packages/prefect/workers/base.py", line 1281, in _submit_run_and_capture_errors
result = await self.run(
^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 723, in run
) = await run_sync_in_worker_thread(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect/utilities/asyncutils.py", line 233, in run_sync_in_worker_thread
result = await anyio.to_thread.run_sync(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/anyio/to_thread.py", line 56, in run_sync
return await get_async_backend().run_sync_in_worker_thread(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2476, in run_sync_in_worker_thread
return await future
^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 967, in run
result = context.run(func, *args)
^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect/utilities/asyncutils.py", line 243, in call_with_mark
return call()
^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 854, in _create_task_and_wait_for_start
self._report_task_run_creation_failure(configuration, task_run_request, exc)
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 850, in _create_task_and_wait_for_start
task = self._create_task_run(ecs_client, task_run_request)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/tenacity/__init__.py", line 338, in wrapped_f
return copy(f, *args, **kw)
^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/tenacity/__init__.py", line 477, in call
do = self.iter(retry_state=retry_state)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/tenacity/__init__.py", line 378, in iter
result = action(retry_state)
^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/tenacity/__init__.py", line 420, in exc_check
raise retry_exc.reraise()
^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/tenacity/__init__.py", line 187, in reraise
raise self.last_attempt.result()
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/concurrent/futures/_base.py", line 449, in result
return self.__get_result()
^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/concurrent/futures/_base.py", line 401, in __get_result
raise self._exception
File "/usr/local/lib/python3.12/site-packages/tenacity/__init__.py", line 480, in call
result = fn(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/prefect_aws/workers/ecs_worker.py", line 1794, in _create_task_run
task = ecs_client.run_task(**task_run_request)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/botocore/client.py", line 602, in _api_call
return self._make_api_call(operation_name, kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/botocore/context.py", line 123, in wrapper
return func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/botocore/client.py", line 1078, in _make_api_call
raise error_class(parsed_response, operation_name)
botocore.errorfactory.ClientException: An error occurred (ClientException) when calling the RunTask operation: Role is not valid
m
Marvin
10/01/2025, 1:06 PM✅ thought for 74.8 seconds
Marvin
10/01/2025, 1:07 PMThat AWS error means the IAM role on the task definition is invalid for ECS. RunTask is failing before the task starts.
What it’s complaining about
- ECS validates the roles on the task definition:
- executionRoleArn (used by the agent to pull images, write CloudWatch logs, ECS Exec)
- taskRoleArn (assumed by your containers at runtime)
- If either is missing, malformed, not in your account, or has the wrong trust relationship, you’ll get “Role is not valid”.
What to check and fix
1) Identify the exact task definition used
- From the worker logs, grab the ARN shown in “Using ECS task definition …”
- Open that task definition revision in the ECS console and check both:
- executionRoleArn
- taskRoleArn
2) Validate the roles exist and are correct
- They must be full ARNs in your account (not names).
- Both roles must have this trust policy:
Copy code
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service": "<http://ecs-tasks.amazonaws.com|ecs-tasks.amazonaws.com>"
},
"Action": "sts:AssumeRole"
}
]
}m
Madushan Pathirana
10/01/2025, 6:22 PM{
"family": "prefect-flow-runner",
"networkMode": "awsvpc",
"requiresCompatibilities": ["EC2"],
"executionRoleArn": "arnawsiam:REPLACE ME AWS ACCOUNT IDrole/ecsTaskExecutionRole",
"taskRoleArn": "arnawsiam:REPLACE ME AWS ACCOUNT IDrole/YourFlowTaskRole",
"containerDefinitions": [
{
"name": "flow-runner",
"image": "REPLACE_ME_ECR_OR_DOCKER_IMAGE",
"essential": true,
"entryPoint": [],
"command": [],
"cpu": 256,
"memoryReservation": 512,
"logConfiguration": {
"logDriver": "awslogs",
"options": {
"awslogs-group": "/ecs/prefect/flows",
"awslogs-region": "ap-southeast-1",
"awslogs-stream-prefix": "flow"
}
},
"environment": [
// Leave Prefect env empty; the worker will inject PREFECT_API_URL (and API key if Cloud)
]
}
]
}
can you wwrite the docker file for this
@Marvin
m
Marvin
10/01/2025, 6:22 PM✅ thought for 35.3 seconds
Marvin
10/01/2025, 6:23 PMHere’s a clean Dockerfile for your “flow-runner” task definition. It installs your deps and ensures no entrypoint so the ECS worker’s command (
prefect flow-run execute ... Copy code
# Base image with Prefect 3 and Python 3.12
FROM prefecthq/prefect:3-python3.12
# Keep logs unbuffered and pip lean
ENV PYTHONUNBUFFERED=1 \
PIP_NO_CACHE_DIR=1
# OS packages you mentioned
RUN apt-get update && \
apt-get install -y --no-install-recommends git curl && \
rm -rf /var/lib/apt/lists/*
# App directory
WORKDIR /opt/prefect/flows
# Python deps first (for better layer caching)
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt asyncpg
# If your flows import prefect-aws (S3, ECS blocks, etc), also add:
# RUN pip install --no-cache-dir "prefect-aws>=0.4"
# Copy your flow code (adjust as needed)
# COPY . .
# Critical: no entrypoint so Prefect’s command runs verbatim in ECS
ENTRYPOINT []
# No default CMD; ECS worker will provide the command Copy code
docker run --rm <your-image> prefect --version
docker run --rm <your-image> prefect flow-run execute --helpimage"entryPoint": []PREFECT_API_URL2 Views