So a region can be used if needed, but won't be STUN-probed or used as
its home.
This gives us another possible debugging mechanism for #1310, or can
be used as a short-term measure against DERP flip-flops for people
equidistant between regions if our hysteresis still isn't good enough.
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We're beginning to reference DERP region names in the admin UI, so it's
best to consolidate this information in our DERP map.
Signed-off-by: Ross Zurowski <ross@rosszurowski.com>
Instead of hard-coding the DERP map (except for cmd/tailscale netcheck
for now), get it from the control server at runtime.
And make the DERP map support multiple nodes per region with clients
picking the first one that's available. (The server will balance the
order presented to clients for load balancing)
This deletes the stunner package, merging it into the netcheck package
instead, to minimize all the config hooks that would've been
required.
Also fix some test flakes & races.
Fixes#387 (Don't hard-code the DERP map)
Updates #388 (Add DERP region support)
Fixes#399 (wgengine: flaky tests)
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
