In Nomad prior to Consul Connect, all Consul checks work the same
except for Script checks. Because the Task being checked is running in
its own container namespaces, the check is executed by Nomad in the
Task's context. If the Script check passes, Nomad uses the TTL check
feature of Consul to update the check status. This means in order to
run a Script check, we need to know what Task to execute it in.
To support Consul Connect, we need Group Services, and these need to
be registered in Consul along with their checks. We could push the
Service down into the Task, but this doesn't work if someone wants to
associate a service with a task's ports, but do script checks in
another task in the allocation.
Because Nomad is handling the Script check and not Consul anyways,
this moves the script check handling into the task runner so that the
task runner can own the script check's configuration and
lifecycle. This will allow us to pass the group service check
configuration down into a task without associating the service itself
with the task.
When tasks are checked for script checks, we walk back through their
task group to see if there are script checks associated with the
task. If so, we'll spin off script check tasklets for them. The
group-level service and any restart behaviors it needs are entirely
encapsulated within the group service hook.
Updated to hclog.
It exposed fields that required an unexported lock to access. Created a
getter methodn instead. Only old allocrunner currently used this
feature.
This has been done to allow the Server and Client to reuse the same
Syncer because the Agent may be running Client, Server, or both
simultaneously and we only want one Syncer object alive in the agent.
This attribute isn't actually an identifier because it can represent
a collection of services. Rename `serviceIdentifier` to
`serviceRegPrefix which more accurately conveys the intention of this
Syncer attribute.
While here, also rename `SetServiceIdentifier()` to `SetServiceRegPrefix()`
and `GenerateServiceIdentifier()` to `GenerateServicePrefix()`.
SyncServices() immediately attempts to sync whatever information
the process has with Consul. Previously this method would take an
argument of the exclusive list of services that should exist,
however this is not condusive to having a Nomad Client and Nomad
Server share the same consul.Syncer.
I *KNEW* I should have done this when I wrote it, but didn't want to
go back and audit the handlers to include the appropriate return
handling, but now that the code is taking shape, make this change.
In addition to the API changing, consul.Syncer can now be signaled
to shutdown via the Shutdown() method, which will call the Run()'ing
sync task to exit gracefully.
In order to give clients a fighting chance to talk to the right port,
differentiate RPC services from HTTP services by registering two
services with different tags. This yields
`rpc.nomad-server.service.consul` and
`http.nomad-server.service.consul` which is immensely more useful to
clients attempting to bootstrap their world.
There were two `ConsulConfig` structs running around, one of them
needed to go away. Rely on the package's path to provide context
for the type of AgentConfig.
