Eventually remove disconnected nodes from Welcome page display

[luckyredhot]

It is often required to make one time connection of test storage nodes to the grid. Meanwhile these nodes will become forever offline until introducer will be restarted (See Q32 in FAQ: ​https://tahoe-lafs.org/trac/tahoe-lafs/wiki/FAQ#Q32_remove_node).

It would be really nice to have posssibility to remove inactive/legacy nodes from grid (and welcome screen) without restarting introducer. BTW with multiple introducers (#68) restarting each of them will be really complicated. Hence we need a mechanism to easily remove nodes from grid.

[PRabahy]

I wouldn't mind some sort of garbage collection mechanism (if its easier to implement). E.g. Any storage node that hasn't connected for 30 days automatically gets removed.

[zooko]

Please see this tahoe-dev thread, which contains an example of why this is a real problem to users (posted by Anders Genell) and a proposed UI-oriented solution (posted by me).

[gdt]

Several thoughts (for an ideal world)

• There should be a command to run on a node to unregister it from the introducer. People can run this when decommissioning a node.

• The fact that restarting the introducer cleans the nodes list is a bug. This should be persistent. If it isn't persistent, nodes should go away immediately on disconnect.

• It makes sense to have nodes shown as OK/green, DOWN/red (for nodes that have been up in the last 7 days) and STALE/yellow (for nodes that have not been heard from in 7 days). I agree that hiding stale nodes, or putting them in a different section makes sense. DOWN nodes however should stay in order and be loudly pointed out.

• There should be a command on the introducer to remove a node from the list (assuming it is not connected). In a multi-introducer world, this should propagate.

• When a node is removed from the introducer, it should be automatically removed from client nodes. Just fixing this would help a lot.

• Whatever we do, it should not depend on color displays or color vision, or vision at all, but be manifest in the text. (I have nodes with the missing css, and it's really hard to tell what's going on, which is probably a separate issue, and I know the css install is fixed.)

[daira]

See also #1765.

[daira]

This is not just an UI issue. Suppose that we have a node N that is initially pointing to introducer I, and a gateway G that sees an announcement for that node. Then N is reconfigured to point to introducer I2 and restarted. Until G is restarted, it may still use N, even though N is presumably now supposed to be part of a different grid.

FAQ entry ​Q32 is relevant.

[warner]

Milestone renamed

[warner]

renaming milestone

[exarkun]

Moving open issues out of closed milestones.

[meejah]

Ticket retargeted after milestone closed