Volumes, the comic

The pantry that stays full.

The same kitchen as the swarm comic. Cooks come and go all day; what they cook with has to stay. That is what volumes are for, and the networks and ports are the hatches and doors in between.

1 Where the food stays

Every cook has a station. What lies on it belongs to that cook alone: a container’s own files.

When the container is removed and a new one takes its place, the station starts empty. Its own files went with the old one.

So what has to stay goes in the pantry: a volume. Cooks come and go all day; the pantry keeps its shelves.

2 Looking in the pantry

You can look inside without one of your own cooks. A kitchen porter looks for you and goes home again: a short-lived helper container, and looking is read-only.

Fix a label, put a jar in, take one home: edit a text file, upload one, rename or remove it, or download a single file.

Which shelf is fullest? The dashboard names the biggest volumes, and says what is safe to clear out.

3 The cold store

A backup packs the whole pantry into one crate, a .tar archive, and takes it out of the kitchen.

On a schedule, every day or every week, a van takes a crate to a folder you choose, and keeps as many as you say. The oldest ones go.

A cook still stirring in the pantry can leave a crate that does not restore. So the van skips and comes back in an hour, or the cooks pause for a few seconds.

4 Restocking

Restoring puts a crate back. The cooks who use that pantry stop while it happens and start again after, so nobody cooks from a half-filled shelf.

A copy fills a second pantry with the same things, with every label and every lock kept: owners and permissions.

Clear out what nothing uses any more. Leftovers of cooks long gone can go; a pantry you stocked yourself only when you say so, because what is in it is gone after.

5 Hatches and doors

Cooks who have to talk share a hatch: a network. See who stands at which hatch, and move a cook to another one.

The doors to the street are the ports, each with its number. Which cook is behind door 3000? The Ports page says, for every door.

A door on the plan that was never put in: a port that was asked for but not published. The app marks it, and recreating the container fixes it.

The cheat sheet

Every picture above, in Docker words.

A cook’s own station: A container’s own files
The pantry: A volume
The kitchen porter: A short-lived helper container
A label on a jar: A text file in a volume
A crate: A backup, a .tar archive
The van at night: A backup schedule
Putting a crate back: A restore
A second pantry, same shelves: A copy of a volume
Clearing out: Prune
The hatch: A network
A door with a number: A published port
A door on the plan only: A port that was not published

Now look in your own pantry.

Browse a volume, back it up on a schedule, restore it with its users paused, and find every published port on one page.

What the app does with volumes →Swarm, the comic →Download for Windows