This PR allows tuning of heartbeat TTLs. An example of very aggressive
settings is as follows:
```
server {
heartbeat_grace = "1s"
min_heartbeat_ttl = "1s"
max_heartbeats_per_second = 200.0
}
```
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.
This PR:
* Uses Go 1.8 executable lookup
* Stores any err message from stats init method
* Allows overriding of Cpu Compute for hosts where it can't be detected
This PR introduces a parallelism limit during garbage collection. This
is used to avoid large resource usage spikes if garbage collecting many
allocations at once.
* -dev mode defaults bind & advertise to localhost
* Normal mode defaults bind to 0.0.0.0 & advertise to the resolved
hostname. If the hostname resolves to localhost it will refuse to
start and advertise must be manually set.
I apologize in advance for the rather long PR, but unfortunately there
is not an easy way to break this up into smaller chunks. This separates
the agent configuration into smaller, more consumable pieces just like
the job specification.
* Added the keygen command
* Added support for gossip encryption
* Changed the URL for keyring management
* Fixed the cli
* Added some tests
* Added tests for keyring operations
* Added a test for removal of keys
* Added some docs
* Fixed some docs
* Added general options
