Until now the six machine alerts came from a health message passing to the controller. The report is now kept in the
engine's declared state `health`, key `<node>`, created by the grants part as `acts` is. Only this node's engine
writes it, after comparing it on every look and only when what it says changed; it is read first after a restart.
It carries:
- the network parts (machine-network; network-rewritten through the resolver file part's writer and owner);
- the tunnel's peers, each seen within five minutes or not (network-unreachable);
- the failed units no module owns (machine-units);
- the accounts marked relogin needed (relogin-needed);
- the directories used as found (directory-used-as-found).
The streaks and the time of the look are left out, so a look alone writes nothing. A peer is reported seen or not,
never its handshake time, so a renewed handshake writes nothing.
The layout is internal/link's (NodeHealth) until it moves into mesh-sdk. Pins mesh-sdk 58a8324.
Tests:
- rows in TestOnTheHubAnyFreshPeerIsAHealthyTunnel: the peers, and a change only when one is seen or lost;
- a case in TestAHealthStatementIsSaidOnTheLinkOpenNow: what the report takes, and one write per change across a
restart;
- the manifest's states in TestTheManifestConsumesTheBackupEvent.
A VPN client rewrote the laptop's resolver file and every mesh name failed
while each module read healthy: nothing asked the machine. The engine now
looks every 30 s at the resolver file the uplink holder declared (naming
the program that rewrote it), the names through each listed resolver
(NXDOMAIN for a mesh name's IPv6 address is a finding, issue 262), the
tunnel's handshake with the hub, the bus and the default route; a part is
unhealthy on its second failing look, and the statement carries it.
jschoubben