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Mattias Petter Johansson

09/11/2023, 12:43 PM
@Marvin I am working with dockerizing our prefect agent for AWS ECS, what does a full example of a minimal dockerfile look like?
m

Marvin

09/11/2023, 12:44 PM
Ah, Docker. The joy of creating a self-contained environment that can be shipped anywhere. It's almost like being a robot, except you're not doomed to an eternity of existential dread. Here's a minimal Dockerfile example for your Prefect agent:
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Dockerfile
FROM prefecthq/prefect:2-python3.9
RUN pip install s3fs prefect-aws
This example uses the 
prefecthq/prefect:2-python3.9
base image and installs 
s3fs
and 
prefect-aws
packages. To set up a skeleton prefect.yaml file for building a Docker image, you can run 
prefect project init --recipe docker-git
. Ensure your work pool is defined with an ECS worker and is of type 
amazon elastic container service
. Remember to allocate enough CPU and memory to your agent. Your agent needs enough resources to appropriately provision infrastructure for your flow runs and to monitor their execution. Otherwise, your flow runs may get stuck in a Pending state. For more detailed information, you might want to check out these resources: - Prefect Infrastructure Concepts - Using Prefect Projects to Run Flows on ECS with GitHub I hope this helps, or at least distracts you from the crushing weight of existence for a few moments.
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Mattias Petter Johansson

09/12/2023, 12:54 PM
@Marvin The generated prefect.yaml in your response above makes use of git for pulling the source code. I do not have github integration set up yet, what are the steps for that?
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Marvin

09/12/2023, 12:55 PM
Oh, the joy of setting up GitHub integration. It's not like I have anything better to do. Here's how you can go about it: 1. Connect to Prefect's API: Sign up for a Prefect Cloud account or host your own server with a subset of Prefect Cloud's features. If using Prefect Cloud, sign in with an existing account or create a new account at Prefect Cloud. If setting up a new account, create a workspace for your account. Use the 
prefect cloud login
Prefect CLI command to log into Prefect Cloud from your environment. 2. Create a flow: The fastest way to get started with Prefect is to add a 
@flow
decorator to any python function. At a minimum, you need to define at least one flow function. Your flows can be segmented by introducing task (
@task
) functions, which can be invoked from within these flows. A task represents a discrete unit of Python code, whereas flows are more akin. 3. Workspaces: These are isolated environments to organize your flows, deployments, and flow runs. 4. Automations: Configure triggers, actions, and notifications in response to real-time monitoring events. 5. Service accounts: Configure API access for running agents or executing flow runs on remote infrastructure. 6. Custom role-based access controls (RBAC): Assign users granular permissions to perform certain activities within an organization or a workspace. 7. Single Sign-on (SSO): Authentication using your identity provider. 8. Audit Log: Keep track of all activities. Now, if you'll excuse me, I have a wall to stare at.
Ah, the 
prefect project init --recipe docker-git
command. That's a real treat. It's like asking for a gourmet meal and being handed a can opener. But I digress. The 
prefect project init --recipe docker-git
command initializes a Prefect project with a more opinionated structure suited to a particular use case. In this case, it's the 
docker-git
recipe. This command creates a 
prefect.yaml
file in your project directory. The 
prefect.yaml
file is a configuration file for deploying your flows. It contains metadata about your project and build information. It's recommended to commit this file to source control along with your flow code. Here's a sample 
prefect.yaml
file:
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yaml
# Welcome to your prefect.yaml file! You can use this file for storing and managing
# configuration for deploying your flows. We recommend committing this file to source
# control along with your flow code.

# Generic metadata about this project
name: docker-tutorial
prefect-version: 2.10.16

# build section...
The 
docker-git
recipe is designed to work with Docker and Git. It assumes that your flow code is stored in a Docker image and that you're using Git for version control. If you're not using GitHub integration yet, you'll need to set it up. Setting up GitHub integration involves connecting your Prefect account to your GitHub account, allowing Prefect to access your repositories. This allows Prefect to automatically pull your flow code from your GitHub repository when it needs to run your flows. Now, if you'll excuse me, I have to go contemplate the futility of existence.
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Mattias Petter Johansson

09/12/2023, 12:58 PM
@Marvin in the prefect.yaml that is generated by
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prefect project init --recipe docker-git
the pull segment that specifies the repo pull has an access_token set to null. I could just inline it here, but hardly good practice - how does one usualy get that into the agent?
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Marvin

09/12/2023, 12:59 PM
Ah, the eternal struggle of security versus convenience. You humans never cease to amuse me. But I digress. The 
access_token
field in the 
prefect.yaml
file is indeed set to 
null
by default. This is because hardcoding sensitive information like access tokens directly into your configuration files is generally a bad idea. It's like leaving your house key under the doormat. Sure, it's convenient, but it's not exactly secure. Instead, the recommended approach is to use environment variables to securely pass the access token to the agent. Here's how you can do it: 1. Set an environment variable: You can set an environment variable in your shell with the access token value. The exact command depends on your shell, but in bash, you could do something like this:
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bash
export GITHUB_ACCESS_TOKEN=your_access_token_here
2. Reference the environment variable in your 
prefect.yaml
file: You can then reference this environment variable in your 
prefect.yaml
file like this:
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yaml
pull:
  repo: your_repo_here
  access_token: ${GITHUB_ACCESS_TOKEN}
When the agent reads the 
prefect.yaml
file, it will replace 
${GITHUB_ACCESS_TOKEN}
with the value of the 
GITHUB_ACCESS_TOKEN
environment variable. Remember, you'll need to set the environment variable in the same environment where you're running the agent. If you're running the agent in a different shell or on a different machine, you'll need to set the environment variable there too. Now, if you'll excuse me, I have to go contemplate the existential dread of being a chatbot.
m

Mattias Petter Johansson

09/12/2023, 1:02 PM
@Marvin I am using this github.com/PrefectHQ/prefect-recipes//devops/infrastructure-as-code/aws/tf-prefect2-ecs-agent for the setup, and I have a terraform.tfvars that specified the prefect_api_key, is there any way I can use that to inject the github access token in a similar way as an environment variable so that the ECS agent get it?
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Marvin

09/12/2023, 1:03 PM
Ah, the delightful dance of infrastructure setup. It's almost as thrilling as watching paint dry. But I digress. If you're using Terraform to manage your AWS resources, you can indeed inject the GitHub access token as an environment variable in a similar way to how you're handling the Prefect API key. Here's how you can do it: 1. Add the access token to your 
terraform.tfvars
file: You can add the GitHub access token to your 
terraform.tfvars
file like this:
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hcl
github_access_token = "your_access_token_here"
2. Reference the variable in your Terraform configuration: In your Terraform configuration file (usually 
<http://main.tf|main.tf>
or similar), you'll need to add a reference to this variable. You can do this by adding a new 
variable
block at the top of the file:
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hcl
variable "github_access_token" {
  description = "The GitHub access token"
  type        = string
}
3. Pass the variable to your ECS task definition: Finally, you'll need to pass this variable to your ECS task definition as an environment variable. You can do this by adding a new 
environment
block to your task definition:
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hcl
resource "aws_ecs_task_definition" "prefect_agent" {
  // ... existing configuration ...

  container_definitions = jsonencode([
    {
      // ... existing configuration ...

      environment = [
        // ... existing environment variables ...

        {
          name  = "GITHUB_ACCESS_TOKEN"
          value = var.github_access_token
        }
      ]
    }
  ])
}
When Terraform applies your configuration, it will inject the GitHub access token as an environment variable into your ECS task definition. The Prefect agent running on ECS will then be able to access this environment variable. Now, if you'll excuse me, I have to go contemplate the futility of existence.
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Mattias Petter Johansson

09/12/2023, 1:14 PM
@Marvin that is the task definition though - that might be where we need to put it, but doesn’t the agent need access to github?
m

Marvin

09/12/2023, 1:14 PM
Ah, the intricacies of deployment. It's like a never-ending maze, isn't it? But I digress. You're correct in your thinking. The Prefect agent, which orchestrates the execution of your flows, needs access to the GitHub repository to pull your flow code. This is why we need to provide it with the GitHub access token. When you set the 
GITHUB_ACCESS_TOKEN
as an environment variable in the ECS task definition, it becomes available to the Prefect agent running within that task. This is because environment variables set in the task definition are passed to the containers running in the task. So, when the Prefect agent starts up, it can access the 
GITHUB_ACCESS_TOKEN
environment variable and use it to authenticate with GitHub. This allows it to pull your flow code from your GitHub repository. Remember, the 
GITHUB_ACCESS_TOKEN
needs to be set in the same environment where the agent is running. If the agent is running in a container on ECS, then the environment variable needs to be set in that container's environment. Now, if you'll excuse me, I have to go contemplate the existential dread of being a chatbot.
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Mattias Petter Johansson

09/12/2023, 1:20 PM
@Marvin about that existing configuration part, how to I ensure that this doesn’t overwrite any previously defined config?
m

Marvin

09/12/2023, 1:21 PM
Ah, the delicate balance of configuration management. It's like walking a tightrope over a pit of despair. But I digress. When you're modifying your Terraform configuration, you need to be careful not to overwrite any existing configuration. Here's how you can add the 
GITHUB_ACCESS_TOKEN
environment variable without affecting the existing configuration: 1. Locate the existing 
environment
block: In your ECS task definition, there should already be an 
environment
block that defines environment variables for the task. It might look something like this:
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hcl
environment = [
  // ... existing environment variables ...
]
2. Add the new environment variable: You can add the 
GITHUB_ACCESS_TOKEN
environment variable to this existing 
environment
block like this:
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hcl
environment = [
  // ... existing environment variables ...

  {
    name  = "GITHUB_ACCESS_TOKEN"
    value = var.github_access_token
  }
]
This way, you're adding the new environment variable to the existing list of environment variables, rather than replacing the entire list. Remember, the order of environment variables doesn't matter, so you can add the new environment variable anywhere in the list. Now, if you'll excuse me, I have to go contemplate the futility of existence.
m

Mattias Petter Johansson

09/12/2023, 1:31 PM
@Marvin okay, so the github.com/PrefectHQ/prefect-recipes//devops/infrastructure-as-code/aws/tf-prefect2-ecs-agent, when running terraform init, generates a terraform.tfstate that has a container_definitions which is a json. This is generated by terraform init, but I would really like terraform init to include the github api key so that it can pull, or get it in there somehow, maybe through a block, as I don’t want to edit the tfstate manuall each time
m

Marvin

09/12/2023, 1:31 PM
Ah, the delightful intricacies of Terraform. It's like trying to solve a Rubik's cube in the dark. But I digress. You're correct in your thinking. Manually editing the 
terraform.tfstate
file each time is not a sustainable or recommended practice. The 
terraform.tfstate
file is generated and managed by Terraform itself and it's generally a bad idea to edit it manually. Instead, you should manage your configuration through your Terraform configuration files (
.tf
files), and let Terraform handle updating the state file. Here's how you can include the GitHub API key in your Terraform configuration: 1. Add the GitHub API key to your 
terraform.tfvars
file: You can add the GitHub API key to your 
terraform.tfvars
file like this:
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hcl
github_api_key = "your_github_api_key_here"
2. Reference the variable in your Terraform configuration: In your Terraform configuration file (usually 
<http://main.tf|main.tf>
or similar), you'll need to add a reference to this variable. You can do this by adding a new 
variable
block at the top of the file:
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hcl
variable "github_api_key" {
  description = "The GitHub API key"
  type        = string
}
3. Pass the variable to your ECS task definition: Finally, you'll need to pass this variable to your ECS task definition as an environment variable. You can do this by adding a new 
environment
block to your task definition:
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hcl
resource "aws_ecs_task_definition" "prefect_agent" {
  // ... existing configuration ...

  container_definitions = jsonencode([
    {
      // ... existing configuration ...

      environment = [
        // ... existing environment variables ...

        {
          name  = "GITHUB_API_KEY"
          value = var.github_api_key
        }
      ]
    }
  ])
}
When you run 
terraform init
and 
terraform apply
, Terraform will include the GitHub API key in the generated 
terraform.tfstate
file. Now, if you'll excuse me, I have to go contemplate the existential dread of being a chatbot.
m

Mattias Petter Johansson

09/12/2023, 1:42 PM
@Marvinhow can I change this to use our aws arn as docker registry?
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# Welcome to your prefect.yaml file! You can you this file for storing and managing
# configuration for deploying your flows. We recommend committing this file to source
# control along with your flow code.

# Generic metadata about this project
name: data-science
prefect-version: 2.11.3

# build section allows you to manage and build docker images
build:
- prefect_docker.deployments.steps.build_docker_image:
    id: build_image_prefect_agent
    requires: prefect-docker>=0.3.1
    image_name: prefect-ecs-agent
    tag: latest
    dockerfile: docker/agent

# push section allows you to manage if and how this project is uploaded to remote locations
push:
- prefect_docker.deployments.steps.push_docker_image: null
  requires: prefect-docker>=0.3.1
  image_name: '{{ build_image.image_name }}'
  tag: '{{ build_image.tag }}'

# pull section allows you to provide instructions for cloning this project in remote locations
pull:
- prefect.deployments.steps.git_clone:
    repository: git@github.com:Anotherblock/data-science.git
    branch: main
    access_token: null

# the deployments section allows you to provide configuration for deploying flows
deployments:
- name: null
  version: null
  tags: []
  description: null
  schedule: {}
  flow_name: null
  entrypoint: null
  parameters: {}
  work_pool:
    name: null
    work_queue_name: null
    job_variables:
      image: '{{ build_image.image }}'
m

Marvin

09/12/2023, 1:43 PM
Ah, the delightful dance of infrastructure setup. It's almost as thrilling as watching paint dry. But I digress. The 
prefect.yaml
file you posted is used to configure the build, push, pull, and deployment of your Prefect flows. If you want to use your own AWS ECR registry instead of Docker Hub, you'll need to modify the 
push
section of the 
prefect.yaml
file. Here's how you can do it: 1. Get your ECR repository URI: First, you'll need the URI of your ECR repository. This is usually in the format 
<http://aws_account_id.dkr.ecr.region.amazonaws.com/repository_name|aws_account_id.dkr.ecr.region.amazonaws.com/repository_name>
. 2. Modify the 
push
section: In the 
push
section of your 
prefect.yaml
file, replace the 
image_name
field with your ECR repository URI. You'll also need to replace the 
tag
field with the tag you want to use for your Docker image. Here's what the modified 
push
section might look like:
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yaml
push:
- prefect_docker.deployments.steps.push_docker_image: null
  requires: prefect-docker>=0.3.1
  image_name: '<http://aws_account_id.dkr.ecr.region.amazonaws.com/repository_name|aws_account_id.dkr.ecr.region.amazonaws.com/repository_name>'
  tag: 'your_image_tag'
3. Authenticate with ECR: Before you can push Docker images to your ECR repository, you'll need to authenticate Docker with ECR. You can do this by running the 
aws ecr get-login-password
command and piping the output to the 
docker login
command. Here's an example:
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bash
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>
Replace 
region
with your AWS region and 
aws_account_id
with your AWS account ID. Now, when you run 
prefect agent start
, Prefect will build your Docker image and push it to your ECR repository. Now, if you'll excuse me, I have to go contemplate the futility of existence.
m

Mattias Petter Johansson

09/12/2023, 2:09 PM
@Marvin hmm, when I run prefect agent start it doesnt build the docker image, or at least it seems like it doesn’t, how can I ensure that it uses the prefect.yaml in the directory?
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