Network Resources Injector is a Kubernetes Dynamic Admission Controller application that provides functionality of patching Kubernetes pod specifications with requests and limits of custom network resources (managed by device plugins such as intel/sriov-network-device-plugin).
To quickly build and deploy admission controller run:
make image
kubectl apply -f deployments/auth.yaml \
-f deployments/server.yaml
For full installation and troubleshooting steps please see Installation guide.
To see mutating webhook in action you're going to need to add custom resources to your Kubernetes node. In real life scenarios you're going to use network resources managed by network devices plugins, such as intel/sriov-network-device-plugin. There should be net-attach-def CRD already created before you start. In a terminal window start proxy, so that you can easily send HTTP requests to the Kubernetes API server:
kubectl proxy
In another terminal window, execute below command to add 4 example.com/foo resources. Remember to edit <node-name> to match your cluster environment.
curl -s --header "Content-Type: application/json-patch+json" \
--request PATCH \
--data '[{"op": "add", "path": "/status/capacity/example.com~1foo", "value": "4"}]' \
http://localhost:8001/api/v1/nodes/<node-name>/status >/dev/null
Next, you need to create a net-attach-def linked to this example.com/foo resource. To achieve that execute below command:
cat <<EOF | kubectl create -f -
apiVersion: k8s.cni.cncf.io/v1
kind: NetworkAttachmentDefinition
metadata:
annotations:
k8s.v1.cni.cncf.io/resourceName: example.com/foo
name: foo-network
namespace: default
spec:
config: |
{
"cniVersion": "0.3.0",
"name": "foo-network",
"type": "bridge",
"bridge": "br0",
"isGateway": true,
"ipam":
{
"type": "host-local",
"subnet": "172.36.0.0/24",
"dataDir": "/mnt/cluster-ipam"
}
}
EOF
Finally, schedule a pod that will take advantage of automated network resources injection. Use below example, to attach 2 foo-network networks and inject resources accordingly.
cat <<EOF | kubectl create -f -
apiVersion: v1
kind: Pod
metadata:
name: webhook-demo
annotations:
k8s.v1.cni.cncf.io/networks: foo-network, foo-network
spec:
containers:
- image: busybox
resources:
command: ["tail", "-f", "/dev/null"]
imagePullPolicy: IfNotPresent
name: busybox
restartPolicy: Always
EOF
Now verify that resources requests/limits have been properly injected into the first container in the pod. If you have jq installed run this command:
kubectl get pod webhook-demo -o json | jq .spec.containers[0].resources
Expected output showing injected resources in the pod spec, depsite the fact that we have only defined k8s.v1.cni.cncf.io/networks annotation.
{
"limits": {
"example.com/foo": "2"
},
"requests": {
"example.com/foo": "2"
}
}
Alternatively, grep output of kubectl to get the same information.
kubectl get pod webhook-demo -o yaml | grep resources -A4
resources:
limits:
example.com/foo: "2"
requests:
example.com/foo: "2"
As the last step perform cleanup by removing net-attach-def, pod and custom example.com/foo resources. To do that, simply run:
curl --header "Content-Type: application/json-patch+json" \
--request PATCH \
--data '[{"op": "remove", "path": "/status/capacity/example.com~1foo"}]' \
http://localhost:8001/api/v1/nodes/<node-name>/status
kubectl delete net-attach-def foo-network
kubectl delete pod webhook-demo
To create the vendor folder invoke the following which will create a vendor folder.
make vendorIf you wish to not add any client CAs to the servers TLS endpoint, add --insecure flag to webhook binary arguments (See server.yaml).
By default, we consume the client CA from the Kubernetes service account secrets directory /var/run/secrets/kubernetes.io/serviceaccount/.
If you wish to consume a client CA from a different location, please specify flag --client-ca with a valid path. If you wish to add more than one client CA, repeat this flag multiple times. If --client-ca is defined, the default client CA from the service account secrets directory will not be consumed.
In Kubernetes 1.20, an alpha feature was added to expose the requested hugepages to the container via the Downward API.
Being alpha, this feature is disabled in Kubernetes by default.
If enabled when Kubernetes is deployed via FEATURE_GATES="DownwardAPIHugePages=true", then Network Resource Injector can be used to mutate the pod spec to publish the hugepage data to the container. To enable this functionality in Network Resource Injector, add --injectHugepageDownApi flag to webhook binary arguments (See server.yaml).
Like the other Downward API provided data, hugepage information for a pod can be located by an application at the path /etc/podnetinfo/ in the container's file system.
This directory will contain the request and limit information for 1Gi/2Mb.
1Gi Hugepages:
Requests: /etc/podnetinfo/hugepages_1G_request_${CONTAINER_NAME}
Limits: /etc/podnetinfo/hugepages_1G_limit_${CONTAINER_NAME}
2Mb: Hugepages:
Requests: /etc/podnetinfo/hugepages_2M_request_${CONTAINER_NAME}
Limits: /etc/podnetinfo/hugepages_2M_limit_${CONTAINER_NAME}
NOTE: To aid the application, when hugepage fields are being requested via the Downward API, Network Resource Injector also mutates the pod spec to add the environment variable
CONTAINER_NAMEwith the container's name applied.
If a NetworkAttachmentDefinition CR annotation k8s.v1.cni.cncf.io/nodeSelector is present and a pod utilizes this network, Network Resources Injector will add this node selection constraint into the pod spec field nodeSelector. Injecting a single node selector label is currently supported.
Example:
apiVersion: k8s.cni.cncf.io/v1
kind: NetworkAttachmentDefinition
metadata:
name: test-network
annotations:
k8s.v1.cni.cncf.io/nodeSelector: master=eno3
spec:
config: '{
"cniVersion": "0.3.1",
"type": "macvlan",
"master": "eno3",
"mode": "bridge",
}'
...Pod spec after modification by Network Resources Injector:
apiVersion: v1
kind: Pod
metadata:
name: testpod
annotations:
k8s.v1.cni.cncf.io/networks: test-network
spec:
..
nodeSelector:
master: eno3