Fixes#2827
This is a tradeoff. The pro is that you can run separate client and
server agents on the same node and advertise both. The con is that if a
Nomad agent crashes and isn't restarted on that node in the same mode
its entry will not be cleaned up.
That con scenario seems far less likely to occur than the scenario on
the pro side, and even if we do leak an agent entry the checks will be
failing so nothing should attempt to use it.
This PR adds watching of allocation health at the client. The client can
watch for health based on the tasks running on time and also based on
the consul checks passing.
Ideally DriverNetwork would be fully populated in Driver.Prestart, but
Docker doesn't assign the container's IP until you start the container.
However, it's important to setup the port env vars before calling
Driver.Start, so Prestart should populate that.
Previously was interpolating the original task's services again.
Fixes#2180
Also fixes a slight memory leak in the new consul agent. Script check
handles weren't being deleted after cancellation.
Previous implementation assumed all struct fields were included in
service and check IDs. Service IDs never include port labels and check
IDs *optionally* include port labels, so lots of things had to change.
Added a really big test to exercise this.
Fixes#2478#2474#1995#2294
The new client only handles agent and task service advertisement. Server
discovery is mostly unchanged.
The Nomad client agent now handles all Consul operations instead of the
executor handling task related operations. When upgrading from an
earlier version of Nomad existing executors will be told to deregister
from Consul so that the Nomad agent can re-register the task's services
and checks.
Drivers - other than qemu - now support an Exec method for executing
abritrary commands in a task's environment. This is used to implement
script checks.
Interfaces are used extensively to avoid interacting with Consul in
tests that don't assert any Consul related behavior.
