@Marvin I have a flow that is deployed to a docker image on AWS ECR. I have a machine that is running a

prefect worker start

. What is the proper way to authenticate that machine to the ECR docker registry ?

To authenticate a machine with the AWS Elastic Container Registry (ECR) when using Prefect, you'll need to ensure that you have the proper AWS permissions and that Docker is installed on the machine, as Docker is required to pull images from your ECR registry. Based on the information retrieved from the Prefect documentation, the following AWS permissions are necessary to interact with ECR: -

ecr:CreateRepository

-

ecr:DescribeRepositories

-

ecr:GetAuthorizationToken

If you want to use AWS-managed policies, you could use the policy

AmazonEC2ContainerRegistryFullAccess

, but it's important to note that this policy is more permissive than necessary. Here are the generic steps to authenticate with AWS ECR: 1. Ensure the AWS Command Line Interface (CLI) is installed on the machine that is running the

prefect worker start

. 2. Configure AWS credentials on the machine, typically using

aws configure

, to ensure your AWS account and ECR are accessible. 3. Use the

aws ecr get-login-password

command to retrieve an authentication token that you can then use to authenticate your Docker client to the registry by passing this token to

docker login

. The command format would look like this:

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

Replace

<region>

with the AWS region your ECR resides in, and

<aws_account_id>

with your unique AWS account ID. Once authenticated, your machine will be able to pull the necessary Docker images from AWS ECR to execute the Prefect flows. Make sure the worker has the appropriate IAM permissions to perform these operations.

@Marvin I believe that

get-login-password

is generating a temporary credential, so it would not work after 12h. Is there a way to have this auth function run before each flow ?

The Prefect documentation does not specify a built-in method for automatically refreshing AWS ECR credentials before each flow run. The temporary credentials obtained by

get-login-password

indeed expire after a certain period (which could indeed be 12 hours), and this requires some additional handling to ensure that the Docker images can be pulled from ECR when needed. In general, to handle this situation outside of the functionality explicitly documented, you might have a few options: 1. Create a Custom Solution: Write a custom script that authenticates to AWS ECR and embed that within your flow or as a step that runs before your flow starts. This script can be scheduled to run on the machine where the Prefect worker is hosted before each flow is scheduled to start. This could be something like a cron job that runs the AWS ECR login command periodically. 2. Use Prefect's Lifecycle Hooks: Prefect supports lifecycle hooks for flows that allow you to execute code at various stages of the flow. You could consider using

on_start

lifecycle hooks to perform the login operation before the flow runs. 3. Prefect Tasks for Authentication: Create a Prefect task that performs the ECR login operation and set it as the first task in your flow. This ensures that your flow always starts with the latest credentials. 4. ECR Credential Helper: Use the Amazon ECR Docker Credential Helper, which is designed to automatically refresh credentials when pulling Docker images from ECR. You'll need to set it up on the same environment that's running the Prefect worker. Option 2 or 3 may best cater to your need since they embed the authentication step within the flow itself. Unfortunately, without explicit instructions in the Prefect documentation on how to integrate automatic AWS ECR authentication, these suggestions need to be implemented and managed as custom additions to the Prefect setup. You might want to go with a solution that fits best within your infrastructure and operational workflows.