Having the Nomad executor create parent cgroups that rkt is launched
within allows the stats collection code used for the exec driver to Just
Work. The only downside is that now the Nomad executor's resource
utilization counts against the cgroups resource limits just as it does
for the exec driver.
This PR does:
1. Health message based on detection has format "Driver XXX detected"
and "Driver XXX not detected"
2. Set initial health description based on detection status and don't
wait for the first health check.
3. Combine updating attributes on the node, fingerprint and health
checking update for drivers into a single call back.
4. Condensed driver info in `node status` only shows detected drivers
and make the output less wide by removing spaces.
Also don't try to return a DriverNetwork with host networking. None will
ever exist as that's the point of host networking: rkt won't create a
network namespace.
If the container dies before the network can be read, we now ignore the
error coming out of the network information polling loop. Nomad will
restart the task regardless, so we might be masking the actual error.
The polling loop for the rkt network information, inside the `Start`
method, was getting a bit unwieldy. It's been refactored out so it's not
a seperate function.
The network status poll loop for the rkt drivers `Start` method was a
bit messy, and could not display the last encountered error. Here we
clean it up.
The changes introduces in #3256 require at least rkt 1.27.0 because of
a bug in the JSON output of `rkt status` in previous versions.
Here we upgrade all references to rkt's minimum version, and also make
travis and vagrant use this version when running tests.
Finally we add a CHANGELOG notice.
If the rkt driver cannot get the network status, for a task with a
configured port mapping, it will now fail the Start() call and kill the
task instead of simply logging. This matches the Docker behavior.
If no port map is specified, the warnings will be logged but the task
will be allowed to start.
Currently the rkt driver does not expose a DriverNetwork instance after
starting the container, which means that address_mode = 'driver' does
not work.
To get the container network information, we can call `rkt status` on
the UUID of the container and grab the container IP from there.
For the port map, we need to grab the pod manifest as it will tell us
which ports the container exposes. We then cross-reference the
configured port name with the container port names, and use that to
create a correct port mapping.
To avoid doing a (bad) reimplementation of the appc schema(which rkt
uses for its manifest) and rkt apis, we pull those in as vendored
dependencies. The versions used are the same ones that rkt use in their
glide dependency configuration for version 1.28.0.
The rkt driver currently executes run and asks that the pod UUID is
written to a file that is then polled for changes for up to five
seconds. Many container fetches will take longer than this, so this
method will often not be able to track the pod UUID reliably.
To avoid this problem, rkt allows pods to be first prepared, which will
return their UUID, and then run as a second invocation.
Here we convert the rkt driver's Start method to use this method
instead. This way, the UUID will always be tracked correctly.
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.
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.
