Thanks for sharing the step config — I see what’s happening. Why you’re seeing “stale” images: - You’re building a new image on every deploy with a unique tag (

'{{ get-soh-version.stdout }}'

). - You’re also forcing a no‑cache build (

nocache: True

), which guarantees new layers each time. - Docker does not garbage-collect old images/tags automatically, so they accumulate locally. Ways to tackle it 1) Stop forcing full rebuilds unless you need them - Remove

nocache: True

and let Docker layer cache work. In Prefect 3.x, the step parameter is

ignore_cache

(defaults to False), so just omit

nocache

entirely or set:

ignore_cache: false

This will dramatically reduce redundant layers and build time. Docs: prefect-docker integration 2) Keep a stable local tag, but remove the versioned tag after push If you don’t need all historical images locally, keep just a stable tag like

latest

for local use and remove the versioned tag after you push. Example steps snippet:

- prefect_docker.deployments.steps.build_docker_image:
    id: build_image
    requires: prefect-docker>=0.6.1
    image_name: n0vum/soc-estimation_dresden-sued
    tag: '{{ get-soh-version.stdout }}'
    additional_tags:
      - latest
    dockerfile: ./Dockerfile
    buildargs:
      GITLAB_ACCESS_TOKEN: "{{ prefect.blocks.secret.gitlab-token }}"
    network_mode: host
    ignore_cache: false

- prefect_docker.deployments.steps.push_docker_image:
    id: push_image
    image_name: n0vum/soc-estimation_dresden-sued
    tag: '{{ get-soh-version.stdout }}'

# Remove the just-built versioned tag locally to prevent piling up
- prefect_shell.commands.shell_run_command:
    id: cleanup_local_versioned_tag
    command: docker rmi n0vum/soc-estimation_dresden-sued:{{ get-soh-version.stdout }} || true

3) Periodic prune of unused images If you don’t run containers from these images locally, a prune step (either in your deploy or on a schedule) keeps Docker tidy: - Remove dangling layers:

docker image prune -f

- Remove any images not used by containers and older than 24h:

docker image prune -a -f --filter "until=24h"

You can run these with a small

prefect_shell.commands.shell_run_command

step. 4) Optional: prune by label (if you label your images) If your Dockerfile adds a label (e.g.,

LABEL com.prefect.deployment=my-deployment

), you can prune by label:

docker images --filter "label=com.prefect.deployment=my-deployment" -q | tail -n +6 | xargs -r docker rmi

(This keeps the 5 most recent; adjust to taste.) References - Prefect YAML / steps docs: prefect.yaml guide - Docker integration: prefect-docker A couple quick questions to tailor the recommendation: - Are the “stale” ones dangling

<none>:<none>

images, or lots of old versioned tags (e.g.,

:1.2.3

,

:1.2.4

, etc.)? - Are you pushing to a registry as part of deploy, and do you need to keep multiple versions locally for testing?