Pulling large docker containers can take longer than the default
context timeout. Without a way to change this it is very hard for
users to utilise Nomad properly without hacky work arounds.
This change adds an optional pull_timeout config parameter which
gives operators the possibility to account for increase pull times
where needed. The infra docker image also has the option to set a
custom timeout to keep consistency.
* docker: support group allocated ports
* docker: add new ports driver config to specify which group ports are mapped
* docker: update port mapping docs
Fixes#2093
Enable configuring `memory_hard_limit` in the docker config stanza for tasks.
If set, this field will be passed to the container runtime as `--memory`, and
the `memory` configuration from the task resource configuration will be passed
as `--memory_reservation`, creating hard and soft memory limits for tasks using
the docker task driver.
This fixes few cases where driver eventor goroutines are leaked during
normal operations, but especially so in tests.
This change makes few modifications:
First, it switches drivers to use `Context`s to manage shutdown events.
Previously, it relied on callers invoking `.Shutdown()` function that is
specific to internal drivers only and require casting. Using `Contexts`
provide a consistent idiomatic way to manage lifecycle for both internal
and external drivers.
Also, I discovered few places where we don't clean up a temporary driver
instance in the plugin catalog code, where we dispense a driver to
inspect and validate the schema config without properly cleaning it up.
This fixes a bug where docker images may not be GCed. The cause of the
bug is that we track the task using `task.ID+task.Name` on task start
but remove on plain `task.ID`.
This haromize the two paths by using `task.ID`, as it's unique enough
and it's also used in the `loadImage` path (path when loading an image
from a local tarball instead of dockerhub).
Makes it possible to run Linux Containers On Windows with Nomad alongside Windows Containers. Fingerprint prevents only to run Nomad in Windows 10 with Linux Containers
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.
* 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
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.
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.
This commit introduces support for configuring mount propagation when
mounting volumes with the `volume_mount` stanza on Linux targets.
Similar to Kubernetes, we expose 3 options for configuring mount
propagation:
- private, which is equivalent to `rprivate` on Linux, which does not allow the
container to see any new nested mounts after the chroot was created.
- host-to-task, which is equivalent to `rslave` on Linux, which allows new mounts
that have been created _outside of the container_ to be visible
inside the container after the chroot is created.
- bidirectional, which is equivalent to `rshared` on Linux, which allows both
the container to see new mounts created on the host, but
importantly _allows the container to create mounts that are
visible in other containers an don the host_
private and host-to-task are safe, but bidirectional mounts can be
dangerous, as if the code inside a container creates a mount, and does
not clean it up before tearing down the container, it can cause bad
things to happen inside the kernel.
To add a layer of safety here, we require that the user has ReadWrite
permissions on the volume before allowing bidirectional mounts, as a
defense in depth / validation case, although creating mounts should also require
a priviliged execution environment inside the container.
The docker creation API calls may fail with http errors (e.g. timeout)
even if container was successfully created.
Here, we force remove container if we got unexpected failure. We
already do this in some error handlers, and this commit updates all
paths.
I stopped short from a more aggressive refactoring, as the code is ripe
for refactoring and would rather do that in another PR.
This handles a bug where we may start a container successfully, yet we
fail due to retries and startContainer not being idempotent call.
Here, we ensure that when starting a container fails with 500 error,
the retry succeeds if container was started successfully.
Nick Ethier