When the Nomad client restarts and restores allocations, the network namespace
for an allocation may exist but no longer be correctly configured. For example,
if the host is rebooted and the task was a Docker task using a pause container,
the network namespace may be recreated by the docker daemon.
When we restore an allocation, use the CNI "check" command to verify that any
existing network namespace matches the expected configuration. This requires CNI
plugins of at least version 1.2.0 to avoid a bug in older plugin versions that
would cause the check to fail.
If the check fails, destroy the network namespace and try to recreate it from
scratch once. If that fails in the second pass, fail the restore so that the
allocation can be recreated (rather than silently having networking fail).
This should fix the gap left #24650 for Docker task drivers and any other
drivers with the `MustInitiateNetwork` capability.
Fixes: https://github.com/hashicorp/nomad/issues/24292
Ref: https://github.com/hashicorp/nomad/pull/24650
When a Nomad host reboots, the network namespace files in the tmpfs in
`/var/run` are wiped out. So when we restore allocations after a host reboot, we
need to be able to restore both the network namespace and the network
configuration. But because the netns is newly created and we need to run the CNI
plugins again, this create potential conflicts with the IPAM plugin which has
written state to persistent disk at `/var/lib/cni`. These IPs aren't the ones
advertised to Consul, so there's no particular reason to keep them around after
a host reboot because all virtual interfaces need to be recreated too.
Reconfigure the CNI bridge configuration to use `/var/run/cni` as its state
directory. We already expect this location to be created by CNI because the
netns files are hard-coded to be created there too in `libcni`.
Note this does not fix the problem described for Docker in #24292 because that
appears to be related to the netns itself being restored unexpectedly from
Docker's state.
Ref: https://github.com/hashicorp/nomad/issues/24292#issuecomment-2537078584
Ref: https://www.cni.dev/plugins/current/ipam/host-local/#files
The Nomad client can now optionally emit telemetry data from the
prerun and prestart hooks. This allows operators to monitor and
alert on failures and time taken to complete.
The new datapoints are:
- nomad.client.alloc_hook.prerun.success (counter)
- nomad.client.alloc_hook.prerun.failed (counter)
- nomad.client.alloc_hook.prerun.elapsed (sample)
- nomad.client.task_hook.prestart.success (counter)
- nomad.client.task_hook.prestart.failed (counter)
- nomad.client.task_hook.prestart.elapsed (sample)
The hook execution time is useful to Nomad engineering and will
help optimize code where possible and understand job specification
impacts on hook performance.
Currently only the PreRun and PreStart hooks have telemetry
enabled, so we limit the number of new metrics being produced.
When a task restarts, the Nomad client may need to rewrite the Consul token, but
it's created with permissions that prevent a non-root agent from writing to
it. While Nomad clients should be run as root (currently), it's harmless to
allow whatever user the Nomad agent is running as to be able to write to it, and
that's one less barrier to rootless Nomad.
Ref: https://github.com/hashicorp/nomad/issues/23859#issuecomment-2465757392
When multiple templates with api functions are included in a task, it's
possible for consul-template to re-render templates as it creates
watchers, overwriting render event data. This change uses event fields
that do not get overwritten, and only executes the change mode for
templates that were actually written to disk.
---------
Co-authored-by: Tim Gross <tgross@hashicorp.com>
* connect: handle grpc_address as gosockaddr/template string
This PR fixes a bug where the consul.grpc_address could not be set using
a go-sockaddr/template string. This was inconsistent with how we do accept
such strings for consul.address values.
* add changelog
* jobspec: add a chown option to artifact block
This PR adds a boolean 'chown' field to the artifact block.
It indicates whether the Nomad client should chown the downloaded files
and directories to be owned by the task.user. This is useful for drivers
like raw_exec and exec2 which are subject to the host filesystem user
permissions structure. Before, these drivers might not be able to use or
manage the downloaded artifacts since they would be owned by the root
user on a typical Nomad client configuration.
* api: no need for pointer of chown field
When we introduced change_mode=script to templates, we passed the driver handle
down into the template manager so we could call its `Exec` method directly. But
the lifecycle of the driver handle is managed by the taskrunner and isn't
available when the template manager is first created. This has led to a series
of patches trying to fixup the behavior (#15915, #15192, #23663, #23917). Part
of the challenge in getting this right is using an interface to avoid the
circular import of the driver handle.
But the taskrunner already has a way to deal with this problem using a "lazy
handle". The other template change modes already use this indirectly through the
`Lifecycle` interface. Change the driver handle `Exec` call in the template
manager to a new `Lifecycle.Exec` call that reuses the existing behavior. This
eliminates the need for the template manager to know anything at all about the
handle state.
Fixes: https://github.com/hashicorp/nomad/issues/24051
when a CNI result includes an IPv6 address,
set it on the alloc's NetworkStatus for reference.
e.g.:
$ nomad alloc status -json 3dca | jq '.NetworkStatus'
{
"Address": "172.26.64.14",
"AddressIPv6": "fd00:a110:c8::b",
"DNS": null,
"InterfaceName": "eth0"
}
In #23663 we fixed the template hook so that `change_mode="script"` didn't lose
track of the task handle during restores. But this revealed a second bug which
is that access to the handle is not locked while in use, which can allow it to
be removed concurrently.
Fixes: https://github.com/hashicorp/nomad/issues/23875
On supported platforms, the secrets directory is a 1MiB tmpfs. But some tasks
need larger space for downloading large secrets. This is especially the case for
tasks using `templates`, which need extra room to write a temporary file to the
secrets directory that gets renamed to the old file atomically.
This changeset allows increasing the size of the tmpfs in the `resources`
block. Because this is a memory resource, we need to include it in the memory we
allocate for scheduling purposes. The task is already prevented from using more
memory in the tmpfs than the `resources.memory` field allows, but can bypass
that limit by writing to the tmpfs via `template` or `artifact` blocks.
Therefore, we need to account for the size of the tmpfs in the allocation
resources. Simply adding it to the memory needed when we create the allocation
allows it to be accounted for in all downstream consumers, and then we'll
subtract that amount from the memory resources just before configuring the task
driver.
For backwards compatibility, the default value of 1MiB is "free" and ignored by
the scheduler. Otherwise we'd be increasing the allocated resources for every
existing alloc, which could cause problems across upgrades. If a user explicitly
sets `resources.secrets = 1` it will no longer be free.
Fixes: https://github.com/hashicorp/nomad/issues/2481
Ref: https://hashicorp.atlassian.net/browse/NET-10070
For templates with `change_mode = "script"`, we set a driver handle in the
poststart method, so the template runner can execute the script inside the
task. But when the client is restarted and the template contents change during
that window, we trigger a change_mode in the prestart method. In that case, the
hook will not have the handle and so returns an errror trying to run the change
mode.
We restore the driver handle before we call any prestart hooks, so we can pass
that handle in the constructor whenever it's available. In the normal task start
case the handle will be empty but also won't be called.
The error messages are also misleading, as there's no capabilities check
happening here. Update the error messages to match.
Fixes: https://github.com/hashicorp/nomad/issues/15851
Ref: https://hashicorp.atlassian.net/browse/NET-9338
Nomad creates Consul ACL tokens and service registrations to support Consul
service mesh workloads, before bootstrapping the Envoy proxy. Nomad always talks
to the local Consul agent and never directly to the Consul servers. But the
local Consul agent talks to the Consul servers in stale consistency mode to
reduce load on the servers. This can result in the Nomad client making the Envoy
bootstrap request with a tokens or services that have not yet replicated to the
follower that the local client is connected to. This request gets a 404 on the
ACL token and that negative entry gets cached, preventing any retries from
succeeding.
To workaround this, we'll use a method described by our friends over on
`consul-k8s` where after creating the objects in Consul we try to read them from
the local agent in stale consistency mode (which prevents a failed read from
being cached). This cannot completely eliminate this source of error because
it's possible that Consul cluster replication is unhealthy at the time we need
it, but this should make Envoy bootstrap significantly more robust.
This changset adds preflight checks for the objects we create in Consul:
* We add a preflight check for ACL tokens after we login via via Workload
Identity and in the function we use to derive tokens in the legacy
workflow. We do this check early because we also want to use this token for
registering group services in the allocrunner hooks.
* We add a preflight check for services right before we bootstrap Envoy in the
taskrunner hook, so that we have time for our service client to batch updates
to the local Consul agent in addition to the local agent sync.
We've added the timeouts to be configurable via node metadata rather than the
usual static configuration because for most cases, users should not need to
touch or even know these values are configurable; the configuration is mostly
available for testing.
Fixes: https://github.com/hashicorp/nomad/issues/9307
Fixes: https://github.com/hashicorp/nomad/issues/10451
Fixes: https://github.com/hashicorp/nomad/issues/20516
Ref: https://github.com/hashicorp/consul-k8s/pull/887
Ref: https://hashicorp.atlassian.net/browse/NET-10051
Ref: https://hashicorp.atlassian.net/browse/NET-9273
Follow-up: https://hashicorp.atlassian.net/browse/NET-10138
When logging into a JWT auth method, we need to explicitly supply the Consul
admin partition if the local Consul agent is in a partition. We can't derive
this from agent configuration because the Consul agent's configuration is
canonical, so instead we get the partition from the fingerprint (if
available). This changeset updates the Consul client constructor so that we
close over the partition from the fingerprint.
Ref: https://hashicorp.atlassian.net/browse/NET-9451
this is the CE side of an Enterprise-only feature.
a job trying to use this in CE will fail to validate.
to enable daily-scheduled execution entirely client-side,
a job may now contain:
task "name" {
schedule {
cron {
start = "0 12 * * * *" # may not include "," or "/"
end = "0 16" # partial cron, with only {minute} {hour}
timezone = "EST" # anything in your tzdb
}
}
...
and everything about the allocation will be placed as usual,
but if outside the specified schedule, the taskrunner will block
on the client, waiting on the schedule start, before proceeding
with the task driver execution, etc.
this includes a taksrunner hook, which watches for the end of
the schedule, at which point it will kill the task.
then, restarts-allowing, a new task will start and again block
waiting for start, and so on.
this also includes all the plumbing required to pipe API calls
through from command->api->agent->server->client, so that
tasks can be force-run, force-paused, or resume the schedule
on demand.
This change exposes CNI configuration details of a network
namespace as environment variables. This allows a task to use
these value to configure itself; a potential use case is to run
a Raft application binding to IP and Port details configured using
the bridge network mode.
CSI volumes are namespaced. But the client does not include the namespace in the
staging mount path. This causes CSI volumes with the same volume ID but
different namespace to collide if they happen to be placed on the same host. The
per-allocation paths don't need to be namespaced, because an allocation can only
mount volumes from its job's own namespace.
Rework the CSI hook tests to have more fine-grained control over the mock
on-disk state. Add tests covering upgrades from staging paths missing
namespaces.
Fixes: https://github.com/hashicorp/nomad/issues/18741
* drivers/raw_exec: enable setting cgroup override values
This PR enables configuration of cgroup override values on the `raw_exec`
task driver. WARNING: setting cgroup override values eliminates any
gauruntee Nomad can make about resource availability for *any* task on
the client node.
For cgroup v2 systems, set a single unified cgroup path using `cgroup_v2_override`.
The path may be either absolute or relative to the cgroup root.
config {
cgroup_v2_override = "custom.slice/app.scope"
}
or
config {
cgroup_v2_override = "/sys/fs/cgroup/custom.slice/app.scope"
}
For cgroup v1 systems, set a per-controller path for each controller using
`cgroup_v1_override`. The path(s) may be either absolute or relative to
the controller root.
config {
cgroup_v1_override = {
"pids": "custom/app",
"cpuset": "custom/app",
}
}
or
config {
cgroup_v1_override = {
"pids": "/sys/fs/cgroup/pids/custom/app",
"cpuset": "/sys/fs/cgroup/cpuset/custom/app",
}
}
* drivers/rawexec: ensure only one of v1/v2 cgroup override is set
* drivers/raw_exec: executor should error if setting cgroup does not work
* drivers/raw_exec: create cgroups in raw_exec tests
* drivers/raw_exec: ensure we fail to start if custom cgroup set and non-root
* move custom cgroup func into shared file
---------
Co-authored-by: Michael Schurter <mschurter@hashicorp.com>
When available, we provide an environment variable `CONSUL_TOKEN` to tasks, but
this isn't the environment variable expected by the Consul CLI. Job
specifications like deploying an API Gateway become noticeably nicer if we can
instead provide the expected env var.
The `consul_hook` in the allocrunner gets a separate Consul token for each task,
even if the tasks' identities have the same name, but used the identity name as
the key to the alloc hook resources map. This means the last task in the group
overwrites the Consul tokens of all other tasks.
Fix this by adding the task name to the key in the allocrunner's
`consul_hook`. And update the taskrunner's `consul_hook` to expect the task
name in the key.
Fixes: https://github.com/hashicorp/nomad/issues/20374
Fixes: https://hashicorp.atlassian.net/browse/NOMAD-614
Ports are a maximum of uint16, but we have a few places in the recent tproxy
code where we were parsing them as 64-bit wide integers and then downcasting
them to `int`, which is technically unsafe and triggers code scanning alerts. In
practice we've validated the range elsewhere and don't build for 32-bit
platforms. This changeset fixes the parsing to make everything a bit more robust
and silence the alert.
Fixes: https://github.com/hashicorp/nomad-enterprise/security/code-scanning/444
Services can have some of their string fields interpolated. The new Workload
Identity flow doesn't interpolate the services before requesting signed
identities or using those identities to get Consul tokens.
Add support for interpolation to the WID manager and the Consul tokens hook by
providing both with a taskenv builder. Add an "interpolate workload" field to
the WI handle to allow passing the original workload name to the server so the
server can find the correct service to sign.
This changeset also makes two related test improvements:
* Remove the mock WID manager, which was only used in the Consul hook tests and
isn't necessary so long as we provide the real WID manager with the mock
signer and never call `Run` on it. It wasn't feasible to exercise the correct
behavior without this refactor, as the mocks were bypassing the new code.
* Fixed swapped expect-vs-actual assertions on the `consul_hook` tests.
Fixes: https://github.com/hashicorp/nomad/issues/20025
The `getPortMapping` method forces callers to handle two different data
structures, but only one caller cares about it. We don't want to return a single
map or slice because the `cni.PortMapping` object doesn't include a label field
that we need for tproxy. Return a new datastructure that closes over both a
slice of `cni.PortMapping` and a map of label to index in that slice.
When `transparent_proxy` block is present and the network mode is `bridge`, use
a different CNI configuration that includes the `consul-cni` plugin. Before
invoking the CNI plugins, create a Consul SDK `iptables.Config` struct for the
allocation. This includes:
* Use all the `transparent_proxy` block fields
* The reserved ports are added to the inbound exclusion list so the alloc is
reachable from outside the mesh
* The `expose` blocks and `check` blocks with `expose=true` are added to the
inbound exclusion list so health checks work.
The `iptables.Config` is then passed as a CNI argument to the `consul-cni`
plugin.
Ref: https://github.com/hashicorp/nomad/issues/10628
This PR adds a job mutator which injects constraints on the job taskgroups
that make use of bridge networking. Creating a bridge network makes use of the
CNI plugins: bridge, firewall, host-local, loopback, and portmap. Starting
with Nomad 1.5 these plugins are fingerprinted on each node, and as such we
can ensure jobs are correctly scheduled only on nodes where they are available,
when needed.
In #20007 we fixed a bug where the DNS configuration set by CNI plugins was not
threaded through to the task configuration. This resulted in a regression where
a DNS override set by `dockerd` was not respected for `bridge` mode
networking. Our existing handling of CNI DNS incorrectly assumed that the DNS
field would be empty, when in fact it contains a single empty DNS struct.
Handle this case correctly by checking whether the DNS struct we get back from
CNI has any nameservers, and ignore it if it doesn't. Expand test coverage of
this case.
Fixes: https://github.com/hashicorp/nomad/issues/20174
While investigating a report around possible consul-template shutdown issues,
which didn't bear fruit, I found that some of the logic around template runner
shutdown is unintuitive.
* Add some doc strings to the places where someone might think we should be
obviously stopping the runner or returning early.
* Mark context argument for `Poststart`, `Stop`, and `Update` hooks as unused.
No functional code changes.
* exec2: add client support for unveil filesystem isolation mode
This PR adds support for a new filesystem isolation mode, "Unveil". The
mode introduces a "alloc_mounts" directory where tasks have user-owned
directory structure which are bind mounts into the real alloc directory
structure. This enables a task driver to use landlock (and maybe the
real unveil on openbsd one day) to isolate a task to the task owned
directory structure, providing sandboxing.
* actually create alloc-mounts-dir directory
* fix doc strings about alloc mount dir paths
* exec2: implement dynamic workload users taskrunner hook
This PR impelements a TR hook for allocating dynamic workload users from
a pool managed by the Nomad client. This adds a new task driver Capability,
DynamicWorkloadUsers - which a task driver must indicate in order to make
use of this feature.
The client config plumbing is coming in a followup PR - in the RFC we
realized having a client.users block would be nice to have, with some
additional unrelated options being moved from the deprecated client.options
config.
* learn to spell
CNI plugins may set DNS configuration, but this isn't threaded through to the
task configuration so that we can write it to the `/etc/resolv.conf` file as
needed. Add the `AllocNetworkStatus` to the alloc hook resources so they're
accessible from the taskrunner. Any DNS entries provided by the user will
override these values.
Fixes: https://github.com/hashicorp/nomad/issues/11102
