A grant is four facts and a credential — the provision, the machine, the port, and
who the consumer is when it connects — and it is the whole mechanism by which
anything in the mesh reaches anything else. The mesh asserted it and never found
out whether it was true. Issue 145 is what that cost: eleven hours of 'every module
current with its source' while a module could not reach its database.
The consumer verifies it, from its own network position. Not the control plane,
which reaches the address by a path no consumer uses. Not the machine, whose own
packets carried a source address the filter admitted while every container's was
refused — so a host-side check would have passed throughout the outage it exists to
catch. That is inference from the rule that was loaded, stated as such.
A connection and nothing more; speaking each provision's protocol would be a second
implementation of every provision. One failure is not news, only consecutive ones,
and the count is reported rather than the last attempt. A consumer that is not
running reads unchecked, which is a different sentence from broken.
What it costs to be wrong is the constraint on all of it: a check that calls a
working provision broken trains a reader to ignore the report.
Converging the control node closed every path by which a module reached another by
the machine's own name, and it ran for eleven hours while the mesh answered 'all
doing what they were told, all heard from, running what the mesh would send them,
and every module current with its source'.
6,154 database failures in one module's log, beginning at the minute of the flip.
The service accepted TCP and never answered HTTP. Every check the mesh makes
passed, because every check the mesh makes is about the relationship between the
mesh and a machine — applied, current, containers running. None asks whether a
module can reach what it requires, though the mesh composes every grant and so
knows exactly who requires what.
The filter fault is fixed. The eleven hours are the measurement, not the bug.
Also records on 144 that 'more closed than the mesh believes' was harmless only
for what is reached from outside, and an outage for what is reached from within.
jschoubben