Protect against a panic when we attempt to start a container with a name
that conflicts with an existing one. If the existing one is being
deleted while nomad first attempts to create the container, the
createContainer will fail with `container already exists`, but we get
nil container reference from the `containerByName` lookup, and cause a
crash.
I'm not certain how we get into the state, except for being very
unlucky. I suspect that this case may be the result of a concurrent
restart or the docker engine API not being fully consistent (e.g. an
earlier call purged the container, but docker didn't free up resources
yet to create a new container with the same name immediately yet).
If that's the case, then re-attempting creation will hopefully succeed,
or we'd at least fail enough times for the alloc to be rescheduled to
another node.
Looks like the latest `github.com/docker/docker/registry.ResolveAuthConfig` expect
`github.com/docker/docker/api/types.AuthConfig` rather than
`github.com/docker/cli/cli/config/types.AuthConfig`. The two types are
identical but live in different packages.
Here, we embed `registry.ResolveAuthConfig` from upstream repo, but with
the signature we need.
This fixes a bug where executor based drivers emit stats every second,
regardless of user configuration.
When serializing the Stats request across grpc, the nomad agent dropped
the Interval value, and then executor uses 1s as a default value.
* Making pull activity timeout configurable in Docker plugin config, first pass
* Fixing broken function call
* Fixing broken tests
* Fixing linter suggestion
* Adding documentation on new parameter in Docker plugin config
* Adding unit test
* Setting min value for pull_activity_timeout, making pull activity duration a private var
Stop joining libcontainer executor process into the newly created task
container cgroup, to ensure that the cgroups are fully destroyed on
shutdown, and to make it consistent with other plugin processes.
Previously, executor process is added to the container cgroup so the
executor process resources get aggregated along with user processes in
our metric aggregation.
However, adding executor process to container cgroup adds some
complications with much benefits:
First, it complicates cleanup. We must ensure that the executor is
removed from container cgroup on shutdown. Though, we had a bug where
we missed removing it from the systemd cgroup. Because executor uses
`containerState.CgroupPaths` on launch, which includes systemd, but
`cgroups.GetAllSubsystems` which doesn't.
Second, it may have advese side-effects. When a user process is cpu
bound or uses too much memory, executor should remain functioning
without risk of being killed (by OOM killer) or throttled.
Third, it is inconsistent with other drivers and plugins. Logmon and
DockerLogger processes aren't in the task cgroups. Neither are
containerd processes, though it is equivalent to executor in
responsibility.
Fourth, in my experience when executor process moves cgroup while it's
running, the cgroup aggregation is odd. The cgroup
`memory.usage_in_bytes` doesn't seem to capture the full memory usage of
the executor process and becomes a red-harring when investigating memory
issues.
For all the reasons above, I opted to have executor remain in nomad
agent cgroup and we can revisit this when we have a better story for
plugin process cgroup management.
Copy the updated version of freeport (sdk/freeport), and tweak it for use
in Nomad tests. This means staying below port 10000 to avoid conflicts with
the lib/freeport that is still transitively used by the old version of
consul that we vendor. Also provide implementations to find ephemeral ports
of macOS and Windows environments.
Ports acquired through freeport are supposed to be returned to freeport,
which this change now also introduces. Many tests are modified to include
calls to a cleanup function for Server objects.
This should help quite a bit with some flakey tests, but not all of them.
Our port problems will not go away completely until we upgrade our vendor
version of consul. With Go modules, we'll probably do a 'replace' to swap
out other copies of freeport with the one now in 'nomad/helper/freeport'.
Operators commonly have docker logs aggregated using various tools and
don't need nomad to manage their docker logs. Worse, Nomad uses a
somewhat heavy docker api call to collect them and it seems to cause
problems when a client runs hundreds of log collections.
Here we add a knob to disable log aggregation completely for nomad.
When log collection is disabled, we avoid running logmon and
docker_logger for the docker tasks in this implementation.
The downside here is once disabled, `nomad logs ...` commands and API
no longer return logs and operators must corrolate alloc-ids with their
aggregated log info.
This is meant as a stop gap measure. Ideally, we'd follow up with at
least two changes:
First, we should optimize behavior when we can such that operators don't
need to disable docker log collection. Potentially by reverting to
using pre-0.9 syslog aggregation in linux environments, though with
different trade-offs.
Second, when/if logs are disabled, nomad logs endpoints should lookup
docker logs api on demand. This ensures that the cost of log collection
is paid sparingly.
Looks like the RecoverTask doesn't set taskHandle.logger field causing
a panic when the handle attempts to log (e.g. when Shutdown or Signaling
fails).
When a job has a task group network, this log line ends up being
misleading if you're trying to debug networking issues. We really only
care about this when there's no port map set, in which case we get the
error returned anyways.
driver.SetConfig is not appropriate for starting up reconciler
goroutine. Some ephemeral driver instances are created for validating
config and we ought not to side-effecting goroutines for those.
We currently lack a lifecycle hook to inject these, so I picked the
`Fingerprinter` function for now, and reconciler should only run after
fingerprinter started.
Use `sync.Once` to ensure that we only start reconciler loop once.
Mahmood Ali