In order to support implicit ACL policies for tasks to get their own
secrets, each task would need to have its own ACL token. This would
add extra raft overhead as well as new garbage collection jobs for
cleaning up task-specific ACL tokens. Instead, Nomad will create a
workload Identity Claim for each task.
An Identity Claim is a JSON Web Token (JWT) signed by the server’s
private key and attached to an Allocation at the time a plan is
applied. The encoded JWT can be submitted as the X-Nomad-Token header
to replace ACL token secret IDs for the RPCs that support identity
claims.
Whenever a key is is added to a server’s keyring, it will use the key
as the seed for a Ed25519 public-private private keypair. That keypair
will be used for signing the JWT and for verifying the JWT.
This implementation is a ruthlessly minimal approach to support the
secure variables feature. When a JWT is verified, the allocation ID
will be checked against the Nomad state store, and non-existent or
terminal allocation IDs will cause the validation to be rejected. This
is sufficient to support the secure variables feature at launch
without requiring implementation of a background process to renew
soon-to-expire tokens.
This PR fixes a bug where client configuration max_kill_timeout was
not being enforced. The feature was introduced in 9f44780 but seems
to have been removed during the major drivers refactoring.
We can make sure the value is enforced by pluming it through the DriverHandler,
which now uses the lesser of the task.killTimeout or client.maxKillTimeout.
Also updates Event.SetKillTimeout to require both the task.killTimeout and
client.maxKillTimeout so that we don't make the mistake of using the wrong
value - as it was being given only the task.killTimeout before.
Fix numerous go-getter security issues:
- Add timeouts to http, git, and hg operations to prevent DoS
- Add size limit to http to prevent resource exhaustion
- Disable following symlinks in both artifacts and `job run`
- Stop performing initial HEAD request to avoid file corruption on
retries and DoS opportunities.
**Approach**
Since Nomad has no ability to differentiate a DoS-via-large-artifact vs
a legitimate workload, all of the new limits are configurable at the
client agent level.
The max size of HTTP downloads is also exposed as a node attribute so
that if some workloads have large artifacts they can specify a high
limit in their jobspecs.
In the future all of this plumbing could be extended to enable/disable
specific getters or artifact downloading entirely on a per-node basis.
This PR modifies raw_exec and exec to ensure the cgroup for a task
they are driving still exists during a task restart. These drivers
have the same bug but with different root cause.
For raw_exec, we were removing the cgroup in 2 places - the cpuset
manager, and in the unix containment implementation (the thing that
uses freezer cgroup to clean house). During a task restart, the
containment would remove the cgroup, and when the task runner hooks
went to start again would block on waiting for the cgroup to exist,
which will never happen, because it gets created by the cpuset manager
which only runs as an alloc pre-start hook. The fix here is to simply
not delete the cgroup in the containment implementation; killing the
PIDs is enough. The removal happens in the cpuset manager later anyway.
For exec, it's the same idea, except DestroyTask is called on task
failure, which in turn calls into libcontainer, which in turn deletes
the cgroup. In this case we do not have control over the deletion of
the cgroup, so instead we hack the cgroup back into life after the
call to DestroyTask.
All of this only applies to cgroups v2.
This commit performs refactoring to pull out common service
registration objects into a new `client/serviceregistration`
package. This new package will form the base point for all
client specific service registration functionality.
The Consul specific implementation is not moved as it also
includes non-service registration implementations; this reduces
the blast radius of the changes as well.
This PR replaces use of time.After with a safe helper function
that creates a time.Timer to use instead. The new function returns
both a time.Timer and a Stop function that the caller must handle.
Unlike time.NewTimer, the helper function does not panic if the duration
set is <= 0.
Some operators use very long group/task `shutdown_delay` settings to
safely drain network connections to their workloads after service
deregistration. But during incident response, they may want to cause
that drain to be skipped so they can quickly shed load.
Provide a `-no-shutdown-delay` flag on the `nomad alloc stop` and
`nomad job stop` commands that bypasses the delay. This sets a new
desired transition state on the affected allocations that the
allocation/task runner will identify during pre-kill on the client.
Note (as documented here) that using this flag will almost always
result in failed inbound network connections for workloads as the
tasks will exit before clients receive updated service discovery
information and won't be gracefully drained.
recover
This code just seems incorrect. As it stands today it reports a
successful restore if RecoverTask fails and then DestroyTask succeeds.
This can result in a really annoying bug where it then calls RecoverTask
again, whereby it will probably get ErrTaskNotFound and call DestroyTask
once more.
I think the only reason this has not been noticed so far is because most
drivers like Docker will return Success, then nomad will call
RecoverTask, get an error (not found) and call DestroyTask again, and
get a ErrTasksNotFound err.
This commit ensures Nomad captures the task code more reliably even when the task is killed. This issue affect to `raw_exec` driver, as noted in https://github.com/hashicorp/nomad/issues/10430 .
We fix this issue by ensuring that the TaskRunner only calls `driver.WaitTask` once. The TaskRunner monitors the completion of the task by calling `driver.WaitTask` which should return the task exit code on completion. However, it also could return a "context canceled" error if the agent/executor is shutdown.
Previously, when a task is to be stopped, the killTask path makes two WaitTask calls, and the second returns "context canceled" occasionally because of a "race" in task shutting down and depending on driver, and how fast it shuts down after task completes.
By having a single WaitTask call and consistently waiting for the task, we ensure we capture the exit code reliably before the executor is shutdown or the contexts expired.
I opted to change the TaskRunner implementation to avoid changing the driver interface or requiring 3rd party drivers to update.
Additionally, the PR ensures that attempts to kill the task terminate when the task "naturally" dies. Without this change, if the task dies at the right moment, the `killTask` call may retry to kill an already-dead task for up to 5 minutes before giving up.
Add a new driver capability: RemoteTasks.
When a task is run by a driver with RemoteTasks set, its TaskHandle will
be propagated to the server in its allocation's TaskState. If the task
is replaced due to a down node or draining, its TaskHandle will be
propagated to its replacement allocation.
This allows tasks to be scheduled in remote systems whose lifecycles are
disconnected from the Nomad node's lifecycle.
See https://github.com/hashicorp/nomad-driver-ecs for an example ECS
remote task driver.
Use the MemoryMaxMB as the LinuxResources limit. This is intended to ease
drivers implementation and adoption of the features: drivers that use
`resources.LinuxResources.MemoryLimitBytes` don't need to be updated.
Drivers that use NomadResources will need to updated to track the new
field value. Given that tasks aren't guaranteed to use up the excess
memory limit, this is a reasonable compromise.
As newer versions of Consul are released, the minimum version of Envoy
it supports as a sidecar proxy also gets bumped. Starting with the upcoming
Consul v1.9.X series, Envoy v1.11.X will no longer be supported. Current
versions of Nomad hardcode a version of Envoy v1.11.2 to be used as the
default implementation of Connect sidecar proxy.
This PR introduces a change such that each Nomad Client will query its
local Consul for a list of Envoy proxies that it supports (https://github.com/hashicorp/consul/pull/8545)
and then launch the Connect sidecar proxy task using the latest supported version
of Envoy. If the `SupportedProxies` API component is not available from
Consul, Nomad will fallback to the old version of Envoy supported by old
versions of Consul.
Setting the meta configuration option `meta.connect.sidecar_image` or
setting the `connect.sidecar_task` stanza will take precedence as is
the current behavior for sidecar proxies.
Setting the meta configuration option `meta.connect.gateway_image`
will take precedence as is the current behavior for connect gateways.
`meta.connect.sidecar_image` and `meta.connect.gateway_image` may make
use of the special `${NOMAD_envoy_version}` variable interpolation, which
resolves to the newest version of Envoy supported by the Consul agent.
Addresses #8585#7665
* docker: support group allocated ports
* docker: add new ports driver config to specify which group ports are mapped
* docker: update port mapping docs
task shutdown_delay will currently only run if there are registered
services for the task. This implementation detail isn't explicity stated
anywhere and is defined outside of the service stanza.
This change moves shutdown_delay to be evaluated after prekill hooks are
run, outside of any task runner hooks.
just use time.sleep
This commit is an initial (read: janky) approach to forwarding state
from an allocrunner hook to a taskrunner using a similar `hookResources`
approach that tr's use internally.
It should eventually probably be replaced with something a little bit
more message based, but for things that only come from pre-run hooks,
and don't change, it's probably fine for now.
This changeset is some pre-requisite boilerplate that is required for
introducing CSI volume management for client nodes.
It extracts out fingerprinting logic from the csi instance manager.
This change is to facilitate reusing the csimanager to also manage the
node-local CSI functionality, as it is the easiest place for us to
guaruntee health checking and to provide additional visibility into the
running operations through the fingerprinter mechanism and goroutine.
It also introduces the VolumeMounter interface that will be used to
manage staging/publishing unstaging/unpublishing of volumes on the host.
This changeset implements the initial registration and fingerprinting
of CSI Plugins as part of #5378. At a high level, it introduces the
following:
* A `csi_plugin` stanza as part of a Nomad task configuration, to
allow a task to expose that it is a plugin.
* A new task runner hook: `csi_plugin_supervisor`. This hook does two
things. When the `csi_plugin` stanza is detected, it will
automatically configure the plugin task to receive bidirectional
mounts to the CSI intermediary directory. At runtime, it will then
perform an initial heartbeat of the plugin and handle submitting it to
the new `dynamicplugins.Registry` for further use by the client, and
then run a lightweight heartbeat loop that will emit task events
when health changes.
* The `dynamicplugins.Registry` for handling plugins that run
as Nomad tasks, in contrast to the existing catalog that requires
`go-plugin` type plugins and to know the plugin configuration in
advance.
* The `csimanager` which fingerprints CSI plugins, in a similar way to
`drivermanager` and `devicemanager`. It currently only fingerprints
the NodeID from the plugin, and assumes that all plugins are
monolithic.
Missing features
* We do not use the live updates of the `dynamicplugin` registry in
the `csimanager` yet.
* We do not deregister the plugins from the client when they shutdown
yet, they just become indefinitely marked as unhealthy. This is
deliberate until we figure out how we should manage deploying new
versions of plugins/transitioning them.
When a job is configured with Consul Connect aware tasks (i.e. sidecar),
the Nomad Client should be able to request from Consul (through Nomad Server)
Service Identity tokens specific to those tasks.
Now that alloc.Canonicalize() is called in all alloc sources in the
client (i.e. on state restore and RPC fetching), we no longer need to
check alloc.TaskResources.
alloc.AllocatedResources is always non-nil through alloc runner.
Though, early on, we check for alloc validity, so NewTaskRunner and
TaskEnv must still check. `TestClient_AddAllocError` test validates
that behavior.
makeAllocTaskServices did not do a nil check on AllocatedResources
which causes a panic when upgrading directly from 0.8 to 0.10. While
skipping 0.9 is not supported we intend to fix serious crashers caused
by such upgrades to prevent cluster outages.
I did a quick audit of the client package and everywhere else that
accesses AllocatedResources appears to be properly guarded by a nil
check.
Currently, there is an issue when running on Windows whereby under some
circumstances the Windows stats API's will begin to return errors (such
as internal timeouts) when a client is under high load, and potentially
other forms of resource contention / system states (and other unknown
cases).
When an error occurs during this collection, we then short circuit
further metrics emission from the client until the next interval.
This can be problematic if it happens for a sustained number of
intervals, as our metrics aggregator will begin to age out older
metrics, and we will eventually stop emitting various types of metrics
including `nomad.client.unallocated.*` metrics.
However, when metrics collection fails on Linux, gopsutil will in many cases
(e.g cpu.Times) silently return 0 values, rather than an error.
Here, we switch to returning empty metrics in these failures, and
logging the error at the source. This brings the behaviour into line
with Linux/Unix platforms, and although making aggregation a little
sadder on intermittent failures, will result in more desireable overall
behaviour of keeping metrics available for further investigation if
things look unusual.
Adds a new Prerun and Postrun hooks to manage set up of network namespaces
on linux. Work still needs to be done to make the code platform agnostic and
support Docker style network initalization.
When an alloc runner prestart hook fails, the task runners aren't invoked
and they remain in a pending state.
This leads to terrible results, some of which are:
* Lockup in GC process as reported in https://github.com/hashicorp/nomad/pull/5861
* Lockup in shutdown process as TR.Shutdown() waits for WaitCh to be closed
* Alloc not being restarted/rescheduled to another node (as it's still in
pending state)
* Unexpected restart of alloc on a client restart, potentially days/weeks after
alloc expected start time!
Here, we treat all tasks to have failed if alloc runner prestart hook fails.
This fixes the lockups, and permits the alloc to be rescheduled on another node.
While it's desirable to retry alloc runner in such failures, I opted to treat it
out of scope. I'm afraid of some subtles about alloc and task runners and their
idempotency that's better handled in a follow up PR.
This might be one of the root causes for
https://github.com/hashicorp/nomad/issues/5840 .
