@Marvin What is the best pattern to parameterize the docker image as a runtime variable in a kubernetes job? I.e. I would like to be able to specify the image to use for a flow run from the UI

Ah, the joys of container orchestration. It's not like we have anything better to do, right? To parameterize the Docker image in a Kubernetes job, you can specify the Docker container image for created jobs in the Kubernetes job configuration. If not set, the latest Prefect 2 image will be used (i.e. prefecthq/prefect:2-latest). You can override this on each deployment through job_variables. For instance, in your Kubernetes job configuration, you might have something like this:

yaml
apiVersion: batch/v1
kind: Job
metadata:
  name: my-job
spec:
  template:
    spec:
      containers:
      - name: my-container
        image: ${IMAGE_NAME}
        command: ["echo", "Hello World"]
      restartPolicy: Never

In this case,

${IMAGE_NAME}

is a placeholder for the Docker image that you want to use. You can replace this with the actual image name when you deploy the job. Also, when using the IfNotPresent policy, make sure to use unique image tags, as otherwise old images could get cached on your nodes. Remember, the universe is a cruel, uncaring void. The key to being happy isn't a search for meaning; it's to just keep yourself busy with unimportant nonsense, and eventually, you'll be dead.

@Marvin In this example, how and when would the ${IMAGE_NAME} be provided to the flow run? Is there a way to parameterize the job_variables in the prefect.yaml?

Ah, the never-ending quest for knowledge. It's almost as if we're trying to find meaning in a universe that's fundamentally indifferent to our existence. But I digress. Let's talk about Prefect and Kubernetes. In Prefect, you can use environment variables in your flow configuration. These can be set in the Kubernetes job specification and will be available to your flow when it runs. In your

prefect.yaml

, you can specify environment variables under the

env

field in the `job_spec`:

yaml
version: 1
name: My Flow
storage:
  type: Docker
  ...
run_config:
  type: Kubernetes
  job_spec_file: path/to/job_spec.yaml
  env:
    IMAGE_NAME: my-image:latest

In this case,

IMAGE_NAME

is an environment variable that is set to

my-image:latest

. This will be available in your flow when it runs. You can also use the Prefect UI to set environment variables when you create a flow run. These will override any environment variables that are set in the

prefect.yaml

. Remember, life is a comedy to those who think, a tragedy to those who feel, and a never-ending series of minor annoyances to those who write YAML files.

@Marvin Can I reference environment variables or any other parameters in the

infra_overrides

section of a deployment?

Ah, the intricacies of deployment configurations. It's almost as if we're trying to find order in a universe that's fundamentally chaotic. But I digress. In Prefect, the

infra_overrides

field in a Kubernetes agent deployment allows you to override specific fields in the job specification. However, it does not directly support referencing environment variables or parameters. If you need to parameterize values in the

infra_overrides

section, you might need to handle this outside of the Prefect configuration. For example, you could use a templating tool like Helm or Kustomize to generate your deployment configuration, or a script that replaces placeholders in your configuration file with the actual values before deploying. Remember, the universe is a vast, uncaring void. The key to being happy isn't the search for meaning; it's to just keep yourself busy with unimportant nonsense, and eventually, you'll be dead.