We use capped exponential backoff in several places in the code when handling
failures. The code we've copy-and-pasted all over has a check to see if the
backoff is greater than the limit, but this check happens after the bitshift and
we always increment the number of attempts. This causes an overflow with a
fairly small number of failures (ex. at one place I tested it occurs after only
24 iterations), resulting in a negative backoff which then never recovers. The
backoff becomes a tight loop consuming resources and/or DoS'ing a Nomad RPC
handler or an external API such as Vault. Note this doesn't occur in places
where we cap the number of iterations so the loop breaks (usually to return an
error), so long as the number of iterations is reasonable.
Introduce a helper with a check on the cap before the bitshift to avoid overflow in all
places this can occur.
Fixes: #18199
Co-authored-by: stswidwinski <stan.swidwinski@gmail.com>
* drivers/docker: refactor use of clients in docker driver
This PR refactors how we manage the two underlying clients used by the
docker driver for communicating with the docker daemon. We keep two clients
- one with a hard-coded timeout that applies to all operations no matter
what, intended for use with short lived / async calls to docker. The other
has no timeout and is the responsibility of the caller to set a context
that will ensure the call eventually terminates.
The use of these two clients has been confusing and mistakes were made
in a number of places where calls were making use of the wrong client.
This PR makes it so that a user must explicitly call a function to get
the client that makes sense for that use case.
Fixes#17023
* cr: followup items
This complements the `env` parameter, so that the operator can author
tasks that don't share their Vault token with the workload when using
`image` filesystem isolation. As a result, more powerful tokens can be used
in a job definition, allowing it to use template stanzas to issue all kinds of
secrets (database secrets, Vault tokens with very specific policies, etc.),
without sharing that issuing power with the task itself.
This is accomplished by creating a directory called `private` within
the task's working directory, which shares many properties of
the `secrets` directory (tmpfs where possible, not accessible by
`nomad alloc fs` or Nomad's web UI), but isn't mounted into/bound to the
container.
If the `disable_file` parameter is set to `false` (its default), the Vault token
is also written to the NOMAD_SECRETS_DIR, so the default behavior is
backwards compatible. Even if the operator never changes the default,
they will still benefit from the improved behavior of Nomad never reading
the token back in from that - potentially altered - location.
* client: do not disable memory swappiness if kernel does not support it
This PR adds a workaround for very old Linux kernels which do not support
the memory swappiness interface file. Normally we write a "0" to the file
to explicitly disable swap. In the case the kernel does not support it,
give libcontainer a nil value so it does not write anything.
Fixes#17448
* client: detect swappiness by writing to the file
* fixup changelog
Co-authored-by: James Rasell <jrasell@users.noreply.github.com>
---------
Co-authored-by: James Rasell <jrasell@users.noreply.github.com>
This PR fixes a bug where the docker network pause container would not be
stopped and removed in the case where a node is restarted, the alloc is
moved to another node, the node comes back up. See the issue below for
full repro conditions.
Basically in the DestroyNetwork PostRun hook we would depend on the
NetworkIsolationSpec field not being nil - which is only the case
if the Client stays alive all the way from network creation to network
teardown. If the node is rebooted we lose that state and previously
would not be able to find the pause container to remove. Now, we manually
find the pause container by scanning them and looking for the associated
allocID.
Fixes#17299
* "allow" (don't try to drop) linux capabilities
in the docker test driver harness (see #15181)
* refactor to allow different busybox images
since windows containers need to be the same
version as the underlying OS, and we're
moving from 2016 to 2019
* one docker test was flaky from apparently
being a bit slower on windows, so add Wait()
On Windows the executor returns an error when trying to open the `NUL` device
when we pass it `os.DevNull` for the stdout/stderr paths. Instead of opening the
device, use the discard pipe so that we have platform-specific behavior from the
executor itself.
Fixes: #17148
The `DisableLogCollection` capability was introduced as an experimental
interface for the Docker driver in 0.10.4. The interface has been stable and
allowing third-party task drivers the same capability would be useful for those
drivers that don't need the additional overhead of logmon.
This PR only makes the capability public. It doesn't yet add it to the
configuration options for the other internal drivers.
Fixes: #14636#15686
Tools like `nomad-nodesim` are unable to implement a minimal implementation of
an allocrunner so that we can test the client communication without having to
lug around the entire allocrunner/taskrunner code base. The allocrunner was
implemented with an interface specifically for this purpose, but there were
circular imports that made it challenging to use in practice.
Move the AllocRunner interface into an inner package and provide a factory
function type. Provide a minimal test that exercises the new function so that
consumers have some idea of what the minimum implementation required is.
While working on client status update improvements, I encountered problems
getting tests with the mock driver to correctly restore.
Unlike typical drivers the mock driver doesn't have an external source of truth
for whether the task is running (ex. making API calls to `dockerd` or looking
for a running PID), and so in order to make up that information, it re-parses
the original task config. But the taskrunner doesn't call the encoding step for
`RecoverTask`, only `StartTask`, so the task config the mock driver gets is
missing data.
Update the mock driver to stash the "external" state in the task state that
we'll get from the task runner, so that we don't have to try to recover from the
original `TaskConfig` anymore. This should bring the mock driver closer to the
behavior of the other drivers.
Some Nomad users ship application logs out-of-band via syslog. For these users
having `logmon` (and `docker_logger`) running is unnecessary overhead. Allow
disabling the logmon and pointing the task's stdout/stderr to /dev/null.
This changeset is the first of several incremental improvements to log
collection short of full-on logging plugins. The next step will likely be to
extend the internal-only task driver configuration so that cluster
administrators can turn off log collection for the entire driver.
---
Fixes: #11175
Co-authored-by: Thomas Weber <towe75@googlemail.com>
* [no ci] deps: update docker to 23.0.3
This PR brings our docker/docker dependency (which is hosted at github.com/moby/moby)
up to 23.0.3 (forward about 2 years). Refactored our use of docker/libnetwork to
reference the package in its new home, which is docker/docker/libnetwork (it is
no longer an independent repository). Some minor nearby test case cleanup as well.
* add cl
When we added recovery of pause containers in #16352 we called the recovery
function from the plugin factory function. But in our plugin setup protocol, a
plugin isn't ready for use until we call `SetConfig`. This meant that
recovering pause containers was always done with the default
config. Setting up the Docker client only happens once, so setting the wrong
config in the recovery function also means that all other Docker API calls will
use the default config.
Move the `recoveryPauseContainers` call into the `SetConfig`. Fix the error
handling so that we return any error but also don't log when the context is
canceled, which happens twice during normal startup as we fingerprint the
driver.
Currently, the `exec` driver is only setting the Bounding set, which is
not sufficient to actually enable the requisite capabilities for the
task process. In order for the capabilities to survive `execve`
performed by libcontainer, the `Permitted`, `Inheritable`, and `Ambient`
sets must also be set.
Per CAPABILITIES (7):
> Ambient: This is a set of capabilities that are preserved across an
> execve(2) of a program that is not privileged. The ambient capability
> set obeys the invariant that no capability can ever be ambient if it
> is not both permitted and inheritable.
* client/fingerprint: correctly fingerprint E/P cores of Apple Silicon chips
This PR adds detection of asymetric core types (Power & Efficiency) (P/E)
when running on M1/M2 Apple Silicon CPUs. This functionality is provided
by shoenig/go-m1cpu which makes use of the Apple IOKit framework to read
undocumented registers containing CPU performance data. Currently working
on getting that functionality merged upstream into gopsutil, but gopsutil
would still not support detecting P vs E cores like this PR does.
Also refactors the CPUFingerprinter code to handle the mixed core
types, now setting power vs efficiency cpu attributes.
For now the scheduler is still unaware of mixed core types - on Apple
platforms tasks cannot reserve cores anyway so it doesn't matter, but
at least now the total CPU shares available will be correct.
Future work should include adding support for detecting P/E cores on
the latest and upcoming Intel chips, where computation of total cpu shares
is currently incorrect. For that, we should also include updating the
scheduler to be core-type aware, so that tasks of resources.cores on Linux
platforms can be assigned the correct number of CPU shares for the core
type(s) they have been assigned.
node attributes before
cpu.arch = arm64
cpu.modelname = Apple M2 Pro
cpu.numcores = 12
cpu.reservablecores = 0
cpu.totalcompute = 1000
node attributes after
cpu.arch = arm64
cpu.frequency.efficiency = 2424
cpu.frequency.power = 3504
cpu.modelname = Apple M2 Pro
cpu.numcores.efficiency = 4
cpu.numcores.power = 8
cpu.reservablecores = 0
cpu.totalcompute = 37728
* fingerprint/cpu: follow up cr items
* Update ioutil library references to os and io respectively for drivers package
No user facing changes so I assume no change log is required
* Fix failing tests
* docker: disable driver when running as non-root on cgroups v2 hosts
This PR modifies the docker driver to behave like exec when being run
as a non-root user on a host machine with cgroups v2 enabled. Because
of how cpu resources are managed by the Nomad client, the nomad agent
must be run as root to manage docker-created cgroups.
* cl: update cl
* docker: set force=true on remove image to handle images referenced by multiple tags
This PR changes our call of docker client RemoveImage() to RemoveImageExtended with
the Force=true option set. This fixes a bug where an image referenced by more than
one tag could never be garbage collected by Nomad. The Force option only applies to
stopped containers; it does not affect running workloads.
* docker: add note about image_delay and multiple tags
* Ensure infra_image gets proper label used for reconciliation
Currently infra containers are not cleaned up as part of the dangling container
cleanup routine. The reason is that Nomad checks if a container is a Nomad owned
container by verifying the existence of the: `com.hashicorp.nomad.alloc_id` label.
Ensure we set this label on the infra container as well.
* fix unit test
* changelog: add entry
---------
Co-authored-by: Seth Hoenig <shoenig@duck.com>
This PR modifies the configuration of the networking pause contaier to include
the "unless-stopped" restart policy. The pause container should always be
restored into a running state until Nomad itself issues a stop command for the
container.
This is not a _perfect_ fix for #12216 but it should cover the 99% use case -
where a pause container gets accidently stopped / killed for some reason. There
is still a possibility where the pause container and main task container are
stopped and started in the order where the bad behavior persists, but this is
fundamentally unavoidable due to how docker itself abstracts and manages the
underlying network namespace referenced by the containers.
Closes#12216
The exec driver and other drivers derived from the shared executor check the
path of the command before handing off to libcontainer to ensure that the
command doesn't escape the sandbox. But we don't check any host volume mounts,
which should be safe to use as a source for executables if we're letting the
user mount them to the container in the first place.
Check the mount config to verify the executable lives in the mount's host path,
but then return an absolute path within the mount's task path so that we can hand
that off to libcontainer to run.
Includes a good bit of refactoring here because the anchoring of the final task
path has different code paths for inside the task dir vs inside a mount. But
I've fleshed out the test coverage of this a good bit to ensure we haven't
created any regressions in the process.
* client: protect user lookups with global lock
This PR updates Nomad client to always do user lookups while holding
a global process lock. This is to prevent concurrency unsafe implementations
of NSS, but still enabling NSS lookups of users (i.e. cannot not use osusergo).
* cl: add cl
* test: don't use loop vars in goroutines
fixes a data race in the test
* test: copy objects in statestore before mutating
fixes data race in test
* test: @lgfa29's segmgrep rule for loops/goroutines
Found 2 places where we were improperly using loop variables inside
goroutines.
Log lines which include an error should use the full term "error"
as the context key. This provides consistency across the codebase
and avoids a Go style which operators might not be aware of.
Neither the `os.Setenv` nor `t.Setenv` helper are safe to use in parallel tests
because environment variables are process-global. The stdlib panics if you try
to do this. Remove the `ci.Parallel()` call from all tests where we're setting
environment variables.
The QEMU driver can take an optional `graceful_shutdown` configuration
which will create a Unix socket to send ACPI shutdown signal to the VM.
Unix sockets have a hard length limit and the driver implementation
assumed that QEMU versions 2.10.1 were able to handle longer paths. This
is not correct, the linked QEMU fix only changed the behaviour from
silently truncating longer socket paths to throwing an error.
By validating the socket path before starting the QEMU machine we can
provide users a more actionable and meaningful error message, and by
using a shorter socket file name we leave a bit more room for
user-defined values in the path, such as the task name.
The maximum length allowed is also platform-dependant, so validation
needs to be different for each OS.
When a QEMU task is recovered the monitor socket path was not being
restored into the task handler, so the `graceful_shutdown` configuration
was effectively ignored if the client restarted.
OOM detection under cgroups v2 is flaky under versions of `containerd` before
v1.6.3, but our `containerd` dependency is transitive on `moby/moby`, who have
not yet updated. Disable this test for cgroups v2 environments until we can
update the dependency chain.
The `golang.org/x/net/context` package was merged into the stdlib as of go
1.7. Update the imports to use the identical stdlib version. Clean up import
blocks for the impacted files to remove unnecessary package aliasing.
