CLI Machines Docker Prune

`ed machines docker prune`

Reclaims space by removing unused docker objects. Does nothing without --yes.

ed machines docker prune [--json] [--yes] <machine> [<what>]

Arguments

Name	Type / values	Default	What it does
`<machine>`	machine name, ssh alias, id, or any unambiguous prefix	required	Which machine to act on.
`<what>`	`images`, `volumes`, `networks`, `builder` or `system`	`system`	Which family of unused objects to remove.

Options

Name	Type / values	Default	What it does
`--json`	flag	off	Emit JSON on stdout instead of the human lines.
`--yes`	flag	off	Actually prune. Without it nothing is removed.
`--help`, `-h`	flag	off	Print the help for this command on stdout and exit 0.

Each target maps to exactly one docker command, and the dry run prints it:

`<what>`	Command	What goes
`images`	`docker image prune -af`	Every image no container uses, not just the dangling ones.
`volumes`	`docker volume prune -f`	Every volume no container uses, and the data in it.
`networks`	`docker network prune -f`	Every user-defined network nothing is attached to.
`builder`	`docker builder prune -af`	The whole build cache.
`system`	`docker system prune -f`	Stopped containers, unused networks, dangling images and build cache. Volumes are not included.

$ ed machines tuf docker prune
would run: docker system prune -f
pass --yes to do it

`--json` shape

The two shapes differ, which is worth knowing before you parse them. The dry run reports the command it would have run:

{
  "applied": false,
  "command": "docker image prune -af",
  "machine": "Asus TUF 7",
  "target": "images"
}

The applied run reports what docker said instead:

{
  "applied": true,
  "machine": "Asus TUF 7",
  "output": "Total reclaimed space: 3.585GB",
  "target": "images"
}

command is present only when applied is false, and output only when it is true. output is docker's stdout with leading and trailing whitespace trimmed, which for a real prune is a list of deleted ids followed by the reclaimed total. Without --json that same stdout is printed raw.

Examples

ed machines tuf docker prune
ed machines tuf docker prune images --json
ed machines tuf docker prune builder --yes
ed machines tuf docker prune volumes --yes

Behaviour notes

The target is checked before anything else happens, including before the connection is opened, so a typo costs nothing and exits 3 with the valid list:

$ ed machines tuf docker prune everything
error: docker cannot prune everything
hint: try: images, volumes, networks, builder, system

volumes is spelled out as its own target rather than folded into system on purpose. docker system prune does not touch volumes unless it is asked to, and ed never asks it to, so the only way to lose volume data here is to type prune volumes --yes.

prune images is more aggressive than docker image prune typed by hand. The -a means every image without a container, not only the untagged ones, so a tagged image you pulled for later goes too. Check ed machines docker df --json first: the Images row's reclaimableBytes is what this will free.

With --yes the ceiling is 300 seconds, longer than any container verb here and second only to compose pull. A prune that outruns it is reported as a failure while docker keeps going on the machine.