Where does daemon.json live?

On Linux, /etc/docker/daemon.json. On Docker Desktop, it is edited through the app settings UI.

How do I apply changes?

Restart the daemon (systemctl restart docker). Validate first with `dockerd --validate` to catch JSON or option errors.

The Docker daemon.json Guide

daemon.json configures the Docker Engine itself — not a single container, but the whole host. A few options prevent the most common production incidents.

Stop disks filling up

By default, container logs grow forever. This one block is the setting people wish they had set sooner:

{
  "log-driver": "json-file",
  "log-opts": { "max-size": "10m", "max-file": "3" }
}

Now each container keeps at most three 10 MB log files.

Use overlay2

"storage-driver": "overlay2" is the modern default and what you want on any current kernel. Avoid legacy drivers like devicemapper.

Survive daemon restarts

"live-restore": true keeps your containers running while the Docker daemon itself restarts or upgrades — essential for zero-downtime host maintenance.

Tune concurrency

max-concurrent-downloads and max-concurrent-uploads smooth out image pulls on busy CI hosts.

Apply changes safely

Edit /etc/docker/daemon.json.
Validate: dockerd --validate.
Restart: systemctl restart docker.

A malformed daemon.json can stop Docker from starting, so always validate first.

Security notes

Never expose the daemon over tcp:// without TLS — it is root-equivalent.
Bind metrics-addr to 127.0.0.1 only.

Open the daemon.json template and ask the workspace to "cap logs at 5 files of 20MB" or "add a registry mirror", then diff the result.