Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesA Docker image that looks unused in summary output may still back a live service. In Christian Anderson’s homelab, docker ps --format '{{.Image}}' printed bare SHA IDs instead of names. He thought unclecode/crawl4ai was unattached, then confirmed it was running, healthy, and serving traffic. Before removing an image, connect it to the containers that use it and check whether those services are doing their intended work.
Why the image looked orphaned
Anderson describes a specific Docker homelab incident: output from docker ps --format '{{.Image}}' showed bare SHA values rather than familiar image names. The unfamiliar output made unclecode/crawl4ai look unused. A closer check showed the image was associated with a running, healthy container that was serving traffic. The incident is his account, not a claim that every Docker version or host formats output the same way. Read Anderson’s account.
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The practical risk is a mistaken cleanup decision: an image that appears unattached in a quick view may be one docker rmi away from affecting a live service if you remove it without checking references. Do not treat a label or short summary as a dependency audit.
Verify which image a running container uses
Use the container’s detailed configuration to connect a container to its configured image. Docker documents docker inspect as a way to return detailed, low-level information about Docker objects, including the image field. Docker’s inspect reference demonstrates reading .Config.Image.
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List running containers with
docker psand identify the container or service whose image looks unfamiliar. -
Print each running container’s name and configured image:
for id in $(docker ps -q); do docker inspect -f '{{.Name}} {{.Config.Image}}' "$id"; doneCompare the resulting image names with the SHA values or other entries you saw in the summary output.
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Check a relevant listening port or another service-specific signal. Anderson used a port check as corroborating evidence; a listening port alone does not prove that a service is working as intended.
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Before any removal, check for references beyond running containers, including stopped containers and workloads you intend to start later.
Inspecting configured image names helps resolve the immediate ambiguity; checking service activity helps establish whether a live workload matters. Neither step should be replaced by an estimated reclaimable-space figure.
What Docker image prune removes
Docker’s documented prune commands have different scopes. The default docker image prune removes dangling images. Adding -a broadens the selection to images not referenced by any container, including containers that are not running. Read the Docker image prune reference before using either command.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →| Command | Documented scope | What to check first |
|---|---|---|
docker image prune |
Dangling images by default | Review what Docker considers dangling and confirm the host’s cleanup policy. |
docker image prune -a |
Images not referenced by any container | Check stopped containers and planned workloads; an image can be needed even when no current container references it. |
These commands are not equivalent to asking whether an image is serving traffic. Prune scope is based on image references; service checks answer a different operational question. If you are uncertain, review the candidate images and references before running broad cleanup rather than treating an unattended prune as a complete safety check.
“Orphaned” has a separate meaning in Compose
In this incident, “orphaned” describes Anderson’s mistaken impression that an image was unattached. Docker Compose uses “orphaned services” for a different relationship: services that are not declared in the current project definition. The Compose ps reference describes an option to include services not declared by the project. That Compose label does not establish whether a particular image is unused or whether a container is stopped.
Configuration on disk may not match the live container
Editing a Compose file or application directory does not necessarily update a container that already exists. Anderson recounts finding restart: unless-stopped in a Compose file while an older container still had restart=no, because it had not been recreated. He also describes changes to environment configuration and application code that did not take effect in already-created containers. These are examples from his setup, not guarantees about every deployment.
When behavior conflicts with the files you expect to be running, inspect the live container rather than assuming the current files have been applied. Determine whether the change requires recreating the container or rebuilding its image, then use the deployment process appropriate to that workload. Verify the resulting container’s configuration and behavior after making the change.
A healthy status is not proof of working service
A health check reports the condition it was configured to test; it does not automatically validate every expected function. Anderson describes a tunnel container that appeared healthy without connecting the expected tunnel, and a GPU workload that fell back to CPU in his particular hardware and software combination. His concise warning was: “Healthy means the process is up. It doesn’t mean it’s doing its job.”
Choose a check that tests the service outcome you care about: for example, verify the expected tunnel connection or confirm that a workload is actually using the intended accelerator. A process status or health indicator is useful evidence, but it is not a substitute for testing the function the service exists to provide.
Reclaimable space is an estimate, not a cleanup plan
Anderson reported four guests 82% to 86% full — Christian Anderson, 2026 — and docker system df showed 6.67 GB shown as reclaimable — Christian Anderson, 2026. His investigation pointed to images and build cache rather than cold data; the cleanup reclaimed about 340 MB reclaimed in the cleanup — Christian Anderson, 2026. These are observations from his homelab, not independently validated benchmarks or typical results for Docker hosts.
He also reports removing 16 superseded tags listed at about 240 MB each but freeing only 60 MB because the builds shared layers. In his cleanup, per-tag sizes therefore did not predict additive storage savings. Some images that were not running were still referenced by Compose files, another reason the apparent reclaimable amount did not serve as a complete inventory of safe-to-remove workloads.
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Anderson says he grew guest disks online using capacity from an existing thin pool. That was a choice for his Proxmox and storage setup, not a universal storage prescription. The general lesson is narrower: identify what is actually consuming space, understand shared-layer effects, and review image references before pruning.
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