@Marvin Is it possible to reference a block in the job variables in my prefect.yaml? (Prefect 3.x)

Yes, in Prefect 3.x, you can reference Prefect blocks in your

prefect.yaml

file using the syntax

{{ prefect.blocks.block_type.block_slug }}

. This is particularly useful for including sensitive information, like credentials, without hardcoding them in plaintext. For more detailed information, you can refer to the Prefect documentation on prefect.yaml.

@Marvin Is it also possible to reference it in the environment variables part of the job variables?

In Prefect 3.x, you can reference blocks in the

environment variables

section of job variables within your

prefect.yaml

file. You can use the syntax

{{ prefect.blocks.block_type.block_slug }}

to include these references. This allows you to dynamically set environment variables using values stored in Prefect blocks, which is particularly useful for sensitive information. For more details, refer to the Prefect documentation on prefect.yaml.

@Marvin Do you have an example?

Here's an example of how you might reference a Prefect block in the

environment variables

section of a

prefect.yaml

file:

yaml
version: 1

build:
  - prefect.builds.steps.set_working_directory:
      directory: /path/to/your/repo

deploy:
  - prefect.deployments.steps.upload_to_storage:
      storage_block: my-s3-bucket

infrastructure:
  - prefect.infrastructure.process:
      env:
        MY_SECRET: "{{ prefect.blocks.secret.my_secret_block }}"

In this example, the

MY_SECRET

environment variable is set using a value from a Prefect block of type

secret

with the slug

my_secret_block

. This ensures that the secret value is used securely without hardcoding it in the YAML file. Adjust the block type and slug to match your specific use case.

@Marvin I have a secret config and I only want to assign a key of that config to an environment variable

To assign a specific key from a secret configuration block to an environment variable in your

prefect.yaml

, you can use dot notation to reference the key within the block. Here's an example:

yaml
version: 1

build:
  - prefect.builds.steps.set_working_directory:
      directory: /path/to/your/repo

deploy:
  - prefect.deployments.steps.upload_to_storage:
      storage_block: my-s3-bucket

infrastructure:
  - prefect.infrastructure.process:
      env:
        MY_SECRET_KEY: "{{ prefect.blocks.secret.my_secret_block.key_name }}"

In this example: -

my_secret_block

is the slug of your secret block. -

key_name

is the specific key within the secret block that you want to reference. Ensure that the block and key names match those defined in your Prefect setup. This approach allows you to securely access just the necessary part of your secret configuration.

@Marvin If I do so I get this error: "Could not resolve the keypath in the block document data."

The error you're encountering, "Could not resolve the keypath in the block document data," suggests that Prefect is unable to find the specific key within the block you are referencing. This could be due to a few reasons: 1. Incorrect Keypath: Ensure that the keypath you are using correctly matches the structure of the data stored in the block. Prefect uses dot notation to access nested data, so verify that each part of the path is correct. 2. Block Type: The block you are referencing must be of a type that supports nested key access, such as JSON or Dict. If it's a simple string or another unsupported type, accessing a key within it will fail. 3. Feature Implementation: The ability to access specific keys within blocks using keypaths is a relatively new feature. Ensure that your Prefect version includes this functionality by checking the release notes or updating to the latest version. Here's an example of how you might structure your

prefect.yaml

if you have a JSON block:

yaml
version: 1

infrastructure:
  - prefect.infrastructure.process:
      env:
        MY_SECRET_KEY: "{{ prefect.blocks.json.my_secret_block.key_name }}"

Make sure that: -

my_secret_block

is the correct slug of your JSON block. -

key_name

is the exact key within the JSON structure. If you continue to face issues, you might want to check the content of your block in the Prefect UI to ensure it matches the expected structure. For more detailed guidance, you can follow the GitHub pull request that introduced this feature.