Symbols on sensors, places and groups

A dashboard of names is harder to read than it looks. "Router", "Router: ping" and "Gateway" are three rows of text that mean three different things, and the eye has to read every one of them. A symbol beside the name is what lets it stop reading.

Any sensor, any place and the heading of any group can carry one. The field is in the sensor editor, in the site editor, and in Settings → Monitoring → Groups, and the symbol is then drawn beside the name in every view: the cards, the list, the tree, the wall and the sensor's own detail dialog.

The drawings that ship with the program

Twenty-six of them, drawn by hand in the same line style as the rest of the interface: router, switch, server, NAS, container, cloud, internet, database, disk, processor, Wi-Fi, camera, printer, battery, socket, temperature, light, lock, certificate, alert, e-mail, phone, laptop, screen, clock and label. Nothing is downloaded and nothing is fetched: they live inside the binary.

They are also coloured by the text around them rather than carrying a colour of their own, so the same file is right in the dark theme, in the light theme, and under all six accent colours. That is also why a group's heading passes its colour on to the symbol in front of it — the two are one thing to look at.

Your own images

The same picker takes a file: PNG, JPEG or GIF, at most 64 KiB and 512 pixels a side. Once uploaded it appears in the picker under Uploaded, and can be given to any sensor, place or group.

Three things are worth knowing about how that works:

• The bytes go into the database, not into a folder beside it. "One SQLite file, and copying it is the whole backup" is a promise this project makes in three places, and an image kept on disk would quietly make it false: the copy would come back without them.
• SVG is refused, and not as a matter of taste. An SVG is not an image but a document: it may carry script and references to other sites, and it would be served from this dashboard's own address, where that script would run with the session cookie of whoever looked at it. A raster image cannot do that.
• What the file is gets read, not believed. The name and the type the browser sends are both chosen by whoever uploads; the dimensions and the format come from reading the bytes, and a file that is truncated or is not an image at all is refused where the message can still be acted on — in the dialog, next to the field.

Deleting an uploaded image that something still wears is refused, and the refusal says how many sensors, places and groups point at it. Confirming takes it off all of them and deletes it in one go. Nothing breaks if you leave a dangling reference behind: a symbol is a piece of text, not a link, so an image that is gone simply draws nothing.

Groups

A group is a word somebody typed on a sensor — there is no "create group" step anywhere, and no list of groups to keep in step with the sensors. What Settings → Monitoring → Groups holds is what is known about a group once somebody has said more:

Setting	What it does
Icon	the symbol drawn before the heading
Colour	the colour of the heading, and of the symbol in front of it
Position	where the group stands in the order; lower numbers first, and groups with the same number stay alphabetical

The colour is one of six names — azure, violet, emerald, amber, rose, slate — and not a value you type. Every colour in this interface exists twice, once for the dark theme and once for the light one, and a hex value chosen on one of them is wrong on the other.

Forget removes all three and leaves the group alone: the sensors keep the word, and the heading goes on being drawn — plainly, exactly as it was before anybody opened the editor. A group with no settings is not an unfinished group; it is the ordinary state of every group on an installation nobody has decorated.

In the configuration file

A sensor or a site declared in probeglass.yaml may name one:

sites:
  - name: Rack A
    kind: local
    icon: builtin:server

sensors:
  - name: Router
    type: ping
    target: 192.168.1.1
    group: Network
    icon: builtin:router

The two forms are the same two the dashboard writes: builtin:<name> for a drawing that ships with the program, upload:<id> for an image this installation has. They are checked when the file is applied — and by probeglass doctor, which reports them without changing anything — because a file doctor accepts has to be a file serve applies.

That matters more here than it looks. A sensor the file declares is written from the file whole on every start, so a column the file could not name would be cleared each time the daemon came up; an icon set in the dashboard on a file-owned sensor would disappear overnight. The file owns everything about the rows it declares, and that is what it is for.

What a symbol is not

• It is not inherited. A sensor's symbol is its own; a group's heading is drawn from the group's settings. Decorating a group does not decorate the sensors in it.
• It does not change the map's pins. A place on the map is drawn with the pin its kind gives it — that is what tells a rack from a server at a hoster at a glance — and a symbol is what a place shows beside its name in the tree and in the settings list.
• It is not monitored. Nothing about a sensor's checks, its incident, its alerts or its uptime depends on which picture is next to its name.