/node-feature-discovery

Node feature discovery for Kubernetes

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Node feature discovery for Kubernetes

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Overview

This software enables node feature discovery for Kubernetes. It detects hardware features available on each node in a Kubernetes cluster, and advertises those features using node labels.

NFD consists of two software components:

  1. nfd-master is responsible for labeling Kubernetes node objects
  2. nfd-worker is detects features and communicates them to nfd-master. One instance of nfd-worker is supposed to be run on each node of the cluster

Command line interface

You can run NFD in stand-alone Docker containers e.g. for testing purposes. This is useful for checking features-detection.

NFD-Master

When running as a standalone container labeling is expected to fail because Kubernetes API is not available. Thus, it is recommended to use --no-publish command line flag. E.g.

$ docker run --rm --name=nfd-test <NFD_CONTAINER_IMAGE> nfd-master --no-publish
2019/02/01 14:48:21 Node Feature Discovery Master <NFD_VERSION>
2019/02/01 14:48:21 gRPC server serving on port: 8080

Command line flags of nfd-master:

$ docker run --rm <NFD_CONTAINER_IMAGE> nfd-master --help
...
nfd-master.

  Usage:
  nfd-master [--no-publish] [--label-whitelist=<pattern>] [--port=<port>]
     [--ca-file=<path>] [--cert-file=<path>] [--key-file=<path>]
     [--verify-node-name]
  nfd-master -h | --help
  nfd-master --version

  Options:
  -h --help                   Show this screen.
  --version                   Output version and exit.
  --port=<port>               Port on which to listen for connections.
                              [Default: 8080]
  --ca-file=<path>            Root certificate for verifying connections
                              [Default: ]
  --cert-file=<path>          Certificate used for authenticating connections
                              [Default: ]
  --key-file=<path>           Private key matching --cert-file
                              [Default: ]
  --verify-node-name		  Verify worker node name against CN from the TLS
                              certificate. Only has effect when TLS authentication
                              has been enabled.
  --no-publish                Do not publish feature labels
  --label-whitelist=<pattern> Regular expression to filter label names to
                              publish to the Kubernetes API server. [Default: ]

NFD-Worker

In order to run nfd-worker as a "stand-alone" container against your standalone nfd-master you need to run them in the same network namespace:

$ docker run --rm --network=container:nfd-test <NFD_CONTAINER_IMAGE> nfd-worker
2019/02/01 14:48:56 Node Feature Discovery Worker <NFD_VERSION>
...

If you just want to try out feature discovery without connecting to nfd-master, pass the --no-publish flag to nfd-worker.

Command line flags of nfd-worker:

$ docker run --rm <CONTAINER_IMAGE_ID> nfd-worker --help
...
nfd-worker.

  Usage:
  nfd-worker [--no-publish] [--sources=<sources>] [--label-whitelist=<pattern>]
     [--oneshot | --sleep-interval=<seconds>] [--config=<path>]
     [--options=<config>] [--server=<server>] [--server-name-override=<name>]
     [--ca-file=<path>] [--cert-file=<path>] [--key-file=<path>]
  nfd-worker -h | --help
  nfd-worker --version

  Options:
  -h --help                   Show this screen.
  --version                   Output version and exit.
  --config=<path>             Config file to use.
                              [Default: /etc/kubernetes/node-feature-discovery/nfd-worker.conf]
  --options=<config>          Specify config options from command line. Config
                              options are specified in the same format as in the
                              config file (i.e. json or yaml). These options
                              will override settings read from the config file.
                              [Default: ]
  --ca-file=<path>            Root certificate for verifying connections
                              [Default: ]
  --cert-file=<path>          Certificate used for authenticating connections
                              [Default: ]
  --key-file=<path>           Private key matching --cert-file
                              [Default: ]
  --server=<server>           NFD server address to connecto to.
                              [Default: localhost:8080]
  --server-name-override=<name> Name (CN) expect from server certificate, useful
                              in testing
                              [Default: ]
  --sources=<sources>         Comma separated list of feature sources.
                              [Default: cpu,cpuid,iommu,kernel,local,memory,network,pci,pstate,rdt,storage,system]
  --no-publish                Do not publish discovered features to the
                              cluster-local Kubernetes API server.
  --label-whitelist=<pattern> Regular expression to filter label names to
                              publish to the Kubernetes API server. [Default: ]
  --oneshot                   Label once and exit.
  --sleep-interval=<seconds>  Time to sleep between re-labeling. Non-positive
                              value implies no re-labeling (i.e. infinite
                              sleep). [Default: 60s]

NOTE Some feature sources need certain directories and/or files from the host mounted inside the NFD container. Thus, you need to provide Docker with the correct --volume options in order for them to work correctly when run stand-alone directly with docker run. See the template spec for up-to-date information about the required volume mounts.

Feature discovery

Feature sources

The current set of feature sources are the following:

Feature labels

The published node labels encode a few pieces of information:

  • Namespace, i.e. feature.node.kubernetes.io
  • The source for each label (e.g. cpuid).
  • The name of the discovered feature as it appears in the underlying source, (e.g. AESNI from cpuid).
  • The value of the discovered feature.

Feature label names adhere to the following pattern:

<namespace>/<source name>-<feature name>[.<attribute name>]

The last component (i.e. attribute-name) is optional, and only used if a feature logically has sub-hierarchy, e.g. sriov.capable and sriov.configure from the network source.

Note: only features that are available on a given node are labeled, so the only label value published for features is the string "true".

{
  "feature.node.kubernetes.io/cpu-<feature-name>": "true",
  "feature.node.kubernetes.io/cpuid-<feature-name>": "true",
  "feature.node.kubernetes.io/iommu-<feature-name>": "true",
  "feature.node.kubernetes.io/kernel-<feature name>": "<feature value>",
  "feature.node.kubernetes.io/memory-<feature-name>": "true",
  "feature.node.kubernetes.io/network-<feature-name>": "true",
  "feature.node.kubernetes.io/pci-<device label>.present": "true",
  "feature.node.kubernetes.io/pstate-<feature-name>": "true",
  "feature.node.kubernetes.io/rdt-<feature-name>": "true",
  "feature.node.kubernetes.io/storage-<feature-name>": "true",
  "feature.node.kubernetes.io/system-<feature name>": "<feature value>",
  "feature.node.kubernetes.io/<file name>-<feature name>": "<feature value>"
}

The --sources flag controls which sources to use for discovery.

Note: Consecutive runs of node-feature-discovery will update the labels on a given node. If features are not discovered on a consecutive run, the corresponding label will be removed. This includes any restrictions placed on the consecutive run, such as restricting discovered features with the --label-whitelist option.

CPU Features

The CPU feature source differs from the CPUID feature source in that it discovers CPU related features that are actually enabled, whereas CPUID only reports supported CPU capabilities (i.e. a capability might be supported but not enabled) as reported by the cpuid instruction.

Feature name Description
hardware_multithreading Hardware multithreading, such as Intel HTT, enabled (number of locical CPUs is greater than physical CPUs)

X86 CPUID Features (Partial List)

Feature name Description
ADX Multi-Precision Add-Carry Instruction Extensions (ADX)
AESNI Advanced Encryption Standard (AES) New Instructions (AES-NI)
AVX Advanced Vector Extensions (AVX)
AVX2 Advanced Vector Extensions 2 (AVX2)
BMI1 Bit Manipulation Instruction Set 1 (BMI)
BMI2 Bit Manipulation Instruction Set 2 (BMI2)
SSE4.1 Streaming SIMD Extensions 4.1 (SSE4.1)
SSE4.2 Streaming SIMD Extensions 4.2 (SSE4.2)
SGX Software Guard Extensions (SGX)

Arm64 CPUID Features (Partial List)

Feature name Description
AES Announcing the Advanced Encryption Standard
EVSTRM Event Stream Frequency Features
FPHP Half Precision(16bit) Floating Point Data Processing Instructions
ASIMDHP Half Precision(16bit) Asimd Data Processing Instructions
ATOMICS Atomic Instructions to the A64
ASIMRDM Support for Rounding Double Multiply Add/Subtract
PMULL Optional Cryptographic and CRC32 Instructions
JSCVT Perform Conversion to Match Javascript
DCPOP Persistent Memory Support

IOMMU Features

Feature name Description
enabled IOMMU is present and enabled in the kernel

Kernel Features

Feature Attribute Description
config <option name> Kernel config option is enabled (set 'y' or 'm').
Default options are NO_HZ, NO_HZ_IDLE, NO_HZ_FULL and PREEMPT
selinux enabled Selinux is enabled on the node
version full Full kernel version as reported by /proc/sys/kernel/osrelease (e.g. '4.5.6-7-g123abcde')

major First component of the kernel version (e.g. '4')

minor Second component of the kernel version (e.g. '5')

revision Third component of the kernel version (e.g. '6')

Kernel config file to use, and, the set of config options to be detected are configurable. See configuration options for more information.

Local (User-specific Features)

NFD has a special feature source named local which is designed for getting the labels from user-specific feature detector. It provides a mechanism for users to implement custom feature sources in a pluggable way, without modifying nfd source code or Docker images. The local feature source can be used to advertise new user-specific features, and, for overriding labels created by the other feature sources.

The local feature source gets its labels by two different ways:

  • It tries to execute files found under /etc/kubernetes/node-feature-discovery/source.d/ directory. The hook files must be executable. When executed, the hooks are supposed to print all discovered features in stdout, one per line.
  • It reads files found under /etc/kubernetes/node-feature-discovery/features.d/ directory. The file content is expected to be similar to the hook output (described above).

These directories must be available inside the Docker image so Volumes and VolumeMounts must be used if standard NFD images are used.

In both cases, the labels can be binary or non binary, using either <name> or <name>=<value> format.

Unlike the other feature sources, the name of the file, instead of the name of the feature source (that would be local in this case), is used as a prefix in the label name, normally. However, if the <name> of the label starts with a slash (/) it is used as the label name as is, without any additional prefix. This makes it possible for the user to fully control the feature label names, e.g. for overriding labels created by other feature sources.

The value of the label is either true (for binary labels) or <value> (for non-binary labels).

stderr output of the hooks is propagated to NFD log so it can be used for debugging and logging.

A hook example:
User has a shell script /etc/kubernetes/node-feature-discovery/source.d/my-source which has the following stdout output:

MY_FEATURE_1
MY_FEATURE_2=myvalue
/override_source-OVERRIDE_BOOL
/override_source-OVERRIDE_VALUE=123

which, in turn, will translate into the following node labels:

feature.node.kubernetes.io/my-source-MY_FEATURE_1=true
feature.node.kubernetes.io/my-source-MY_FEATURE_2=myvalue
feature.node.kubernetes.io/override_source-OVERRIDE_BOOL=true
feature.node.kubernetes.io/override_source-OVERRIDE_VALUE=123

A file example:
User has a file /etc/kubernetes/node-feature-discovery/features.d/my-source which contains the following lines:

MY_FEATURE_1
MY_FEATURE_2=myvalue
/override_source-OVERRIDE_BOOL
/override_source-OVERRIDE_VALUE=123

which, in turn, will translate into the following node labels:

feature.node.kubernetes.io/my-source-MY_FEATURE_1=true
feature.node.kubernetes.io/my-source-MY_FEATURE_2=myvalue
feature.node.kubernetes.io/override_source-OVERRIDE_BOOL=true
feature.node.kubernetes.io/override_source-OVERRIDE_VALUE=123

NFD tries to run any regular files found from the hooks directory. Any additional data files your hook might need (e.g. a configuration file) should be placed in a separate directory in order to avoid NFD unnecessarily trying to execute these. You can use a subdirectory under the hooks directory, for example /etc/kubernetes/node-feature-discovery/source.d/conf/.

NOTE! NFD will blindly run any executables placed/mounted in the hooks directory. It is the user's responsibility to review the hooks for e.g. possible security implications.

P-State Features

Feature name Description
turbo Turbo frequencies are enabled in Intel pstate driver

Memory Features

Feature Attribute Description
numa
Multiple memory nodes i.e. NUMA architecture detected
nv present NVDIMM device(s) are present

Network Features

Feature Attribute Description
sriov capable Single Root Input/Output Virtualization (SR-IOV) enabled Network Interface Card(s) present

configured SR-IOV virtual functions have been configured

PCI Features

Feature Attribute Description
<device label> present PCI device is detected

<device label> is composed of raw PCI IDs, separated by underscores. The set of fields used in <device label> is configurable, valid fields being class, vendor, device, subsystem_vendor and subsystem_device. Defaults are class and vendor. An example label using the default label fields:

feature.node.kubernetes.io/pci-1200_8086.present=true

Also the set of PCI device classes that the feature source detects is configurable. By default, device classes (0x)03, (0x)0b40 and (0x)12, i.e. GPUs, co-processors and accelerator cards are detected.

See configuration options for more information on NFD config.

RDT (Intel Resource Director Technology) Features

Feature name Description
RDTMON Intel RDT Monitoring Technology
RDTCMT Intel Cache Monitoring (CMT)
RDTMBM Intel Memory Bandwidth Monitoring (MBM)
RDTL3CA Intel L3 Cache Allocation Technology
RDTL2CA Intel L2 Cache Allocation Technology
RDTMBA Intel Memory Bandwidth Allocation (MBA) Technology

Storage Features

Feature name Description
nonrotationaldisk Non-rotational disk, like SSD, is present in the node

System Features

Feature Attribute Description
os_release ID Operating system identifier

VERSION_ID Operating system version identifier (e.g. '6.7')

VERSION_ID.major First component of the OS version id (e.g. '6')

VERSION_ID.minor Second component of the OS version id (e.g. '7')

Getting started

System requirements

  1. Linux (x86_64/Arm64)
  2. [kubectl] kubectl-setup (properly set up and configured to work with your Kubernetes cluster)
  3. [Docker] docker-down (only required to build and push docker images)

Usage

nfd-master

Nfd-master runs as a DaemonSet, by default in the master node(s) only. You can use the template spec provided to deploy nfd-master:

kubectl create -f nfd-master.yaml.template

Nfd-master listens for connections from nfd-worker(s) and connects to the Kubernetes API server to adds node labels advertised by them.

If you have RBAC authorization enabled (as is the default e.g. with clusters initialized with kubeadm) you need to configure the appropriate ClusterRoles, ClusterRoleBindings and a ServiceAccount in order for NFD to create node labels. The provided template will configure these for you.

nfd-worker

Nfd-worker is preferably run as a Kubernetes DaemonSet. There is an example spec that can be used as a template, or, as is when just trying out the service:

kubectl create -f nfd-worker-daemonset.yaml.template

Nfd-worker connects to the nfd-master service to advertise hardware features.

When run as a daemonset, nodes are re-labeled at an interval specified using the --sleep-interval option. In the template the default interval is set to 60s which is also the default when no --sleep-interval is specified.

Feature discovery can alternatively be configured as a one-shot job. There is an example script in this repo that demonstrates how to deploy the job in the cluster.

./label-nodes.sh

The label-nodes.sh script tries to launch as many jobs as there are Ready nodes. Note that this approach does not guarantee running once on every node. For example, if some node is tainted NoSchedule or fails to start a job for some other reason, then some other node will run extra job instance(s) to satisfy the request and the tainted/failed node does not get labeled.

nfd-master and nfd-worker in the same Pod

You can also run nfd-master and nfd-worker inside a single pod:

kubectl apply -f nfd-daemonset-combined.yaml.template

Similar to the nfd-worker setup above, this creates a DaemonSet that schedules an NFD Pod an all worker nodes, with the difference that the Pod also also contains an nfd-master instance. In this case no nfd-master service is run on the master node(s), but, the worker nodes are able to label themselves.

This may be desirable e.g. in single-node setups.

TLS authentication

NFD supports mutual TLS authentication between the nfd-master and nfd-worker instances. That is, nfd-worker and nfd-master both verify that the other end presents a valid certificate.

TLS authentication is enabled by specifying --ca-file, --key-file and --cert-file args, on both the nfd-master and nfd-worker instances. The template specs provided with NFD contain (commented out) example configuration for enabling TLS authentication.

The Common Name (CN) of the nfd-master certificate must match the DNS name of the nfd-master Service of the cluster. By default, nfd-master only check that the nfd-worker has been signed by the specified root certificate (--ca-file). Additional hardening can be enabled by specifying --verify-node-name in nfd-master args, in which case nfd-master verifies that the NodeName presented by nfd-worker matches the Common Name (CN) of its certificate. This means that each nfd-worker requires a individual node-specific TLS certificate.

Usage demo

asciicast

Configuration options

Nfd-worker supports a configuration file. The default location is /etc/kubernetes/node-feature-discovery/nfd-worker.conf, but, this can be changed by specifying the--config command line flag. The file is read inside the container, and thus, Volumes and VolumeMounts are needed to make your configuration available for NFD. The preferred method is to use a ConfigMap. For example, create a config map using the example config as a template:

cp nfd-worker.conf.example nfd-worker.conf
vim nfd-worker.conf  # edit the configuration
kubectl create configmap nfd-worker-config --from-file=nfd-worker.conf

Then, configure Volumes and VolumeMounts in the Pod spec (just the relevant snippets shown below):

...
  containers:
      volumeMounts:
        - name: nfd-worker-config
          mountPath: "/etc/kubernetes/node-feature-discovery/"
...
  volumes:
    - name: nfd-worker-config
      configMap:
        name: nfd-worker-config
...

You could also use other types of volumes, of course. That is, hostPath if different config for different nodes would be required, for example.

The (empty-by-default) example config is used as a config in the NFD Docker image. Thus, this can be used as a default configuration in custom-built images.

Configuration options can also be specified via the --options command line flag, in which case no mounts need to be used. The same format as in the config file must be used, i.e. JSON (or YAML). For example:

--options='{"sources": { "pci": { "deviceClassWhitelist": ["12"] } } }'

Configuration options specified from the command line will override those read from the config file.

Currently, the only available configuration options are related to the PCI and Kernel feature sources.

Building from source

Download the source code.

git clone https://github.com/kubernetes-sigs/node-feature-discovery

Build the container image:

cd <project-root>
make

NOTE: Our default docker image is hosted in quay.io. To override the QUAY_REGISTRY_USER use the -e option as follows: QUAY_REGISTRY_USER=<my-username> make image -e

You can also specify a build tool different from Docker, for example:

make IMAGE_BUILD_CMD="buildah bud"

Push the container image (optional, this example with Docker)

docker push <quay-domain-name>/<registry-user>/<image-name>:<version>

Change the job spec to use your custom image (optional):

To use your published image from the step above instead of the quay.io/kubernetes_incubator/node-feature-discovery image, edit image attribute in the spec template(s) to the new location (<quay-domain-name>/<registry-user>/<image-name>[:<version>]).

Targeting Nodes with Specific Features

Nodes with specific features can be targeted using the nodeSelector field. The following example shows how to target nodes with Intel TurboBoost enabled.

apiVersion: v1
kind: Pod
metadata:
  labels:
    env: test
  name: golang-test
spec:
  containers:
    - image: golang
      name: go1
  nodeSelector:
    feature.node.kubernetes.io/pstate-turbo: 'true'

For more details on targeting nodes, see node selection.

References

Github issues

Design proposal

Governance

This is a SIG-node subproject, hosted under the Kubernetes SIGs organization in Github. The project was established in 2016 as a Kubernetes Incubator project and migrated to Kubernetes SIGs in 2018.

License

This is open source software released under the Apache 2.0 License.

Demo

A demo on the benefits of using node feature discovery can be found in demo.