A Boundary is a container that means something: a cloud region, a VPC, a subnet, a cluster, a trust zone, a system in a C4 diagram. It has a title, a dashed edge and a light tint of its colour, and it carries everything inside it when it moves.
It sits in the palette's Build category in Diagram mode, after Frame and Lane.
Styles
Right-click and open the Boundary section to pick a style:
- Tab Style (the default): the title in a small tab on the top edge, the way cloud vendors draw their regions.
- Inset Style: the title inside the top-left corner. Use it for a boundary nested in another, so the titles don't pile up on the edges.
- C4 Style: the title bold in the bottom-left corner with its type under it in brackets, as the C4 model draws a system boundary.
Double-click to edit the title. Select the boundary and click its second line to type a meta line, such as a CIDR range ("10.0.0.0/16") or a C4 type. Drop an icon on a boundary to put it before the title, a cloud for a region or a lock for a trust zone.
Nesting
Put a boundary inside another and the tints stack, so the deeper a zone is nested, the deeper it reads. Region, VPC and subnet need nothing more than dropping one inside the next. Pick a Background colour in Colours to use your own fill instead.
What it holds
A boundary holds the same things a frame does:
- An element belongs to it when its centre is inside it, and dragging the boundary carries it along.
- Something inside two containers belongs to the smaller one, so a subnet inside a VPC carries its own contents.
- It always paints behind what it holds.
Resizing a boundary leaves its contents where they are. Arrows connect to its edge like any shape, for "Internet to VPC".
Its animations are the ones that keep it still (Trace, Glow, Blink, Shimmer, Gradient and Highlight), since a container that bounces while its contents stay put looks broken. Trace runs a light round the dashed edge.
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