Hello everyone! I use aws for my work. On my MacOS laptop .aws contains configuration files that are responsible for accessing my work cloud. I want to test prefect with another aws account but I'm afraid something might go wrong. As far as I understand, Prefect uses boto3, and boto3 will take configs from the default path. How to distinguish between a working aws profile and a home one, and what is the most important thing how to say about this to Prefect?

In your ~/.aws/credentials, you may have several profiles as shown in the image. You could then create a boto3 session with a specific profile, or set a default session in your Prefect task:

boto3.setup_default_session(profile_name="dev")

But once you move your flows somewhere to production, you may instead leverage IAM roles on your cluster (e.g. AWS EKS or ECS)

Wow! I will definitely try it, thanks for the quick answer, Anna)

hey @Anna Geller! BTW, is there away to pass the the profile or the

~/.aws/credentials

to my local docker agent? I’m starting a docker agent on my mac which is able to pull a docker image from ECR, but since I’m storing the flow on S3, it’s not able to access it; I guess the docker agent is not grabbing my credentials file. Errors:

prefect.S3	INFO	Downloading flow from <s3://xxxx/example-emr-jobs-success-docker-libs/2022-02-18t17-51-14-668658-00-00>
prefect.S3	ERROR	Error downloading Flow from S3: Unable to locate credentials
execute flow-run	ERROR	Failed to load and execute Flow's environment: NoCredentialsError('Unable to locate credentials')

I’m starting my local docker agent using the command:

prefect agent docker start --name "docker-$(hostname)" --label "local_docker_dev-$(hostname)"

I manged to set the ECR credstore configs on

~/docker/config.json

and using the

docker-credential-helper-ecr

so the agent is able to pull the images correctly.

You can pass env variables directly when you start your agent:

prefect agent docker start --env KEY=VALUE --env KEY2=VALUE2

You're kind of mixing multiple issues here so I'm not sure which problem do you try to address 🙂 • If you are using S3 storage, you can configure your aws CLI with credentials before starting the agent. • If you try to configure ECR pull permissions, you need to run this before you start your docker agent (this should update your docker config.json automatically I think):

aws ecr get-login-password --region region | docker login --username AWS --password-stdin <http://aws_account_id.dkr.ecr.region.amazonaws.com|aws_account_id.dkr.ecr.region.amazonaws.com>

• and if you need both, then you need to configure both ☝️

@Anna Geller thanks for your reply. I’ve tried using the env variables, but maybe I’m doing something wrong here. In my AWS EC2 instance the docker agent runs fine because it is using the instance profile. where as in my local machine it seems to be using my

.aws/credentials

file. Can you tell me more about this process of the docker agent loading the credentials? Additionally, while starting the docker agent with the environment variables, it seems to be loading them (I can’t see the values loaded) but is it passed to the docker image? Yes, I forgot to tell you that I am using a custom docker image with custom library code/module - once again works fine on the cloud. the commands I’m using to run the docker agent locally: •

prefect agent docker start --name "docker-$(hostname)" --label "local_docker_dev-$(hostname)" --env AWS_ACCESS_KEY_ID="my_key_id" --env AWS_SECRET_ACCESS_KEY="my_key" --log-level DEBUG

◦ spits out this line, meaning that is creating those environment variables`[2022-03-04 18:33:06,549] DEBUG - docker-MacBook-Pro.local | Environment variables: ['AWS_ACCESS_KEY_ID', 'AWS_SECRET_ACCESS_KEY']` ◦ and outputs this error when I’m running the Flow:

Failed to load and execute Flow's environment: ClientError('An error occurred (InvalidAccessKeyId) when calling the GetObject operation: The AWS Access Key Id you provided does not exist in our records.')

•

prefect agent docker start --name "docker-$(hostname)" --label "local_docker_dev-$(hostname)" --log-level DEBUG

◦ Outputs the following error:

Error downloading Flow from S3: Unable to locate credentials
Failed to load and execute Flow's environment: NoCredentialsError('Unable to locate credentials')

First question on how the credentials are retrieved. That is done here for all AWs tasks and S3 storage. So it will look for secrets first and then default to just using the env variables. These env vars from the agent should be passed to the Flow. Are you on Cloud and do you have Secrets configured?

No I’m not on Prefect Cloud. I’m running prefect core 0.15.x on an EC2 instance (self-hosted). In my description above, I stated that EC2 machines running docker agent work fine by using the instance profile. However, my goal is now to be able to run my flow code locally using a docker agent; but it seems that the docker agent is not able to grab my AWS credentials properly, so I’m trying to understand how to properly pass them, or if there’s any config I need to do before launching the docker agent. Does that mean that I’ve to mount a volume on my local docker with my

~/.aws/.credentials

using the

--volume

https://docs.prefect.io/api/latest/cli/agent.html ?

Ah ok I think it might be easier to get in as well with using local secrets maybe? This feels like it should work though because I think the docker agent spins a new container and then that container pulls the flow from S3. And the env variables are indeed put in there based on your logs. I think a good way to test is to see if you can instantiate a boto3 client after putting those env vars in the container?

Ok I’ll try with volume. I think my logs already show that the container is not able to pick the credentials from the env vars I’m setting (unless I’m doing it incorrectly). How could I use local secrets then, and rely on

PREFECT__CONTEXT__SECRETS__AWS_CREDENTIALS

? https://docs.prefect.io/core/concepts/secrets.html#default-secrets

Yup, that's pretty much how I always do it for local development with Docker - note that you must mount the credentials to the root user, it won't work otherwise:

prefect agent docker start --label AGENT_LABEL --volume ~/.aws:/root/.aws

Here is how I used it in a flow of flows example: https://github.com/anna-geller/packaging-prefect-flows/blob/master/flows/different_images_per_subflows/parent_docker_different_images_per_subflow.py

Hey @Anna Geller / @Kevin Kho I’m having the same issues running a docker agent on a remote host. Simply mounting my

~/.aws

folder won’t work as this is a remote host. What is the recommended way to set env vars on all flow runs? The docs mention

All agents have a --env flag for configuring environment variables to set on all flow runs managed by that agent.

but this does not appear to be working (I’m setting some AWS variables via

-e AWS_ACCESS_KEY_ID=xxx

)

That should work. It gets added to the Flow run. Is your problem accessing an AWS resource from a task or are you trying to load a Flow from S3 storage?

using s3 (fsspec / s3fs to be specific) in a task and getting the following:

File "/usr/local/lib/python3.9/site-packages/botocore/auth.py", line 388, in add_auth
    raise NoCredentialsError()
botocore.exceptions.NoCredentialsError: Unable to locate credentials

Have you tried checking the environment to see if it made it in the container from the agent?

yeah, it doesnt

That’s pretty weird. Are you on Cloud or Server?

cloud

You could just store it as a Prefect secret and then use

Secret.get()

to fetch it inside a task and then you don’t need to juggle passing it through the agent

yeah but thats not going to work for things like AWS that are burried deep in tasks

I find it hard to believe that wouldn’t work. Maybe you can add a log in the agent code here to see if the env var set makes it to

create_container

right underneath the try?

Yeah I thought the agent at some point logged the env vars it was being set with?

Oh I don’t think I’ve seen that explicitly logged cuz it could contain secrets. My current thought is there may be some edge case with the merging logic to get the RunConfig and env vars and add them to the container. This logic is always hard to read. But you could just log this variable after the merge to see

Okay interesting - the env vars are being printed

Uhhh….yeah then that means it’s being handed over to

create_container

right? I’m confused why it wouldn’t end up inside the container as an env var (not even tied to Prefect)

yep

what dockerpy version are you on?

I think this is an issue on my end - on another host it seems to be working