Networking plugin for pod networking in Kubernetes using Elastic Network Interfaces on AWS.
Download the latest version of the yaml and apply it the cluster.
kubectl apply -f aws-k8s-cni.yaml
Launch kubelet with network plugins set to cni (--network-plugin=cni), the cni directories configured (--cni-config-dir
and --cni-bin-dir) and node ip set to the primary IPv4 address of the primary ENI for the instance
(--node-ip=$(curl http://169.254.169.254/latest/meta-data/local-ipv4)).
It is also recommended to set --max-pods equal to (the number of ENIs for the instance type ×
(the number of IPs per ENI - 1)) + 2; for details, see vpc_ip_resource_limit.go. Setting --max-pods will prevent
scheduling that exceeds the IP address resources available to the kubelet.
The default manifest expects --cni-conf-dir=/etc/cni/net.d and --cni-bin-dir=/opt/cni/bin.
Alternatively there is also a Helm chart: eks/aws-vpc-cni
See here for required IAM policies.
makedefaults tomake build-linuxthat builds the Linux binaries.unit-test,format,lintandvetprovide ways to run the respective tests/tools and should be run before submitting a PR.make dockerwill create a docker container using the docker-build with the finished binaries, with a tag ofamazon/amazon-k8s-cni:latestmake docker-builduses a docker container (golang:1.16) to build the binaries.make docker-unit-testsuses a docker container (golang:1.16) to run all unit tests.
There are 2 components:
- CNI Plugin, which will wire up host's and pod's network stack when called.
ipamd, which is a long-running node-Local IP Address Management (IPAM) daemon, is responsible for:- maintaining a warm-pool of available IP addresses, and
- assigning an IP address to a Pod.
The details can be found in Proposal: CNI plugin for Kubernetes networking over AWS VPC.
Troubleshooting Guide provides tips on how to debug and troubleshoot this CNI.
When a worker node first joins the cluster, there is only 1 ENI along with all of its addresses in the ENI. Without any configuration, ipamd always try to keep one extra ENI.
When number of pods running on the node exceeds the number of addresses on a single ENI, the CNI backend start allocating a new ENI and start using following allocation scheme:
For example, a m4.4xlarge node can have up to 8 ENIs, and each ENI can have up to 30 IP addresses. See Elastic Network Interfaces documentation for details.
- If the number of current running Pods is between 0 and 29, ipamd will allocate one more eni. And Warm-Pool size is 2 eni * (30 -1) = 58
- If the number of current running Pods is between 30 and 58, ipamd will allocate 2 more eni. And Warm-Pool size is 3 eni * (30 -1) = 87
For a detailed explanation, see WARM_ENI_TARGET, WARM_IP_TARGET and MINIMUM_IP_TARGET.
The Amazon VPC CNI plugin for Kubernetes supports a number of configuration options, which are set through environment variables. The following environment variables are available, and all of them are optional.
Type: Boolean as a String
Default: true
Specifies whether NodePort services are enabled on a worker node's primary network interface. This requires additional
iptables rules and that the kernel's reverse path filter on the primary interface is set to loose.
Type: Boolean as a String
Default: false
Specifies that your pods may use subnets and security groups that are independent of your worker node's VPC configuration.
By default, pods share the same subnet and security groups as the worker node's primary interface. Setting this variable
to true causes ipamd to use the security groups and VPC subnet in a worker node's ENIConfig for elastic network interface
allocation. You must create an ENIConfig custom resource for each subnet that your pods will reside in, and then annotate or
label each worker node to use a specific ENIConfig (multiple worker nodes can be annotated or labelled with the same ENIConfig).
Worker nodes can only be annotated with a single ENIConfig at a time, and the subnet in the ENIConfig must belong to the
same Availability Zone that the worker node resides in.
For more information, see CNI Custom Networking
in the Amazon EKS User Guide.
Type: String
Default: k8s.amazonaws.com/eniConfig
Specifies node annotation key name. This should be used when AWS_VPC_K8S_CNI_CUSTOM_NETWORK_CFG=true. Annotation value
will be used to set ENIConfig name. Note that annotations take precedence over labels.
Type: String
Default: k8s.amazonaws.com/eniConfig
Specifies node label key name. This should be used when AWS_VPC_K8S_CNI_CUSTOM_NETWORK_CFG=true. Label value will be used
to set ENIConfig name. Note that annotations will take precedence over labels. To use labels ensure annotation with key
k8s.amazonaws.com/eniConfig or defined key (in ENI_CONFIG_ANNOTATION_DEF) is not set on the node.
To select an ENIConfig based upon availability zone set this to failure-domain.beta.kubernetes.io/zone and create an
ENIConfig custom resource for each availability zone (e.g. us-east-1a).
Type: Integer as a String
Default: 9001
Used to configure the MTU size for attached ENIs. The valid range is from 576 to 9001.
Type: Boolean as a String
Default: false
Specifies whether an external NAT gateway should be used to provide SNAT of secondary ENI IP addresses. If set to true, the
SNAT iptables rule and off-VPC IP rule are not applied, and these rules are removed if they have already been applied.
Disable SNAT if you need to allow inbound communication to your pods from external VPNs, direct connections, and external VPCs,
and your pods do not need to access the Internet directly via an Internet Gateway. However, your nodes must be running in a
private subnet and connected to the internet through an AWS NAT Gateway or another external NAT device.
Type: String
Default: prng
Valid Values: hashrandom, prng, none
Specifies whether the SNAT iptables rule should randomize the outgoing ports for connections. This setting takes effect when
AWS_VPC_K8S_CNI_EXTERNALSNAT=false, which is the default setting. The default setting for AWS_VPC_K8S_CNI_RANDOMIZESNAT is
prng, meaning that --random-fully will be added to the SNAT iptables rule. For old versions of iptables that do not
support --random-fully this option will fall back to --random. To disable random port allocation, if you for example
rely on sequential port allocation for outgoing connections set it to none.
Note: Any options other than none will cause outbound connections to be assigned a source port that is not necessarily
part of the ephemeral port range set at the OS level (/proc/sys/net/ipv4/ip_local_port_range). This is relevant for any
customers that might have NACLs restricting traffic based on the port range found in ip_local_port_range.
Type: String
Default: empty
Specify a comma separated list of IPv4 CIDRs to exclude from SNAT. For every item in the list an iptables rule and off-VPC
IP rule will be applied. If an item is not a valid ipv4 range it will be skipped. This should be used when AWS_VPC_K8S_CNI_EXTERNALSNAT=false.
Type: Integer as a String
Default: 1
Specifies the number of free elastic network interfaces (and all of their available IP addresses) that the ipamd daemon should
attempt to keep available for pod assignment on the node. By default, ipamd attempts to keep 1 elastic network interface and all
of its IP addresses available for pod assignment. The number of IP addresses per network interface varies by instance type. For more
information, see IP Addresses Per Network Interface Per Instance Type
in the Amazon EC2 User Guide for Linux Instances.
For example, an m4.4xlarge launches with 1 network interface and 30 IP addresses. If 5 pods are placed on the node and 5 free IP
addresses are removed from the IP address warm pool, then ipamd attempts to allocate more interfaces until WARM_ENI_TARGET free
interfaces are available on the node.
If WARM_IP_TARGET is set, then this environment variable is ignored and the WARM_IP_TARGET behavior is used instead.
Type: Integer
Default: None
Specifies the number of free IP addresses that the ipamd daemon should attempt to keep available for pod assignment on the node. Setting this to a non-positive value is same as setting this to 0 or not setting the variable.
With ENABLE_PREFIX_DELEGATION set to true then ipamd daemon will check if the existing (/28) prefixes are enough to maintain the
WARM_IP_TARGET if it is not sufficient then more prefixes will be attached.
For example,
- if
WARM_IP_TARGETis set to 5, thenipamdattempts to keep 5 free IP addresses available at all times. If the elastic network interfaces on the node are unable to provide these free addresses,ipamdattempts to allocate more interfaces untilWARM_IP_TARGETfree IP addresses are available. ENABLE_PREFIX_DELEGATIONset totrueandWARM_IP_TARGETis 16. Initially 1 (/28) prefix is sufficient but once a single pod is assigned IP then remaining free IPs are 15 hence IPAMD will allocate 1 more prefix to achieve 16WARM_IP_TARGET
NOTE! Avoid this setting for large clusters, or if the cluster has high pod churn. Setting it will cause additional calls to the
EC2 API and that might cause throttling of the requests. It is strongly suggested to set MINIMUM_IP_TARGET when using WARM_IP_TARGET.
If both WARM_IP_TARGET and MINIMUM_IP_TARGET are set, ipamd will attempt to meet both constraints.
This environment variable overrides WARM_ENI_TARGET behavior. For a detailed explanation, see
WARM_ENI_TARGET, WARM_IP_TARGET and MINIMUM_IP_TARGET.
If ENABLE_PREFIX_DELEGATION set to true and WARM_IP_TARGET overrides WARM_PREFIX_TARGET behavior. For a detailed explanation, see
WARM_PREFIX_TARGET, WARM_IP_TARGET and MINIMUM_IP_TARGET.
Type: Integer
Default: None
Specifies the number of total IP addresses that the ipamd daemon should attempt to allocate for pod assignment on the node.
MINIMUM_IP_TARGET behaves identically to WARM_IP_TARGET except that instead of setting a target number of free IP
addresses to keep available at all times, it sets a target number for a floor on how many total IP addresses are allocated. Setting to a
non-positive value is same as setting this to 0 or not setting the variable.
MINIMUM_IP_TARGET is for pre-scaling, WARM_IP_TARGET is for dynamic scaling. For example, suppose a cluster has an
expected pod density of approximately 30 pods per node. If WARM_IP_TARGET is set to 30 to ensure there are enough IPs
allocated up front by the CNI, then 30 pods are deployed to the node, the CNI will allocate an additional 30 IPs, for
a total of 60, accelerating IP exhaustion in the relevant subnets. If instead MINIMUM_IP_TARGET is set to 30 and
WARM_IP_TARGET to 2, after the 30 pods are deployed the CNI would allocate an additional 2 IPs. This still provides
elasticity, but uses roughly half as many IPs as using WARM_IP_TARGET alone (32 IPs vs 60 IPs).
This also improves reliability of the EKS cluster by reducing the number of calls necessary to allocate or deallocate private IPs, which may be throttled, especially at scaling-related times.
Type: Integer
Default: None
Specifies the maximum number of ENIs that will be attached to the node. When MAX_ENI is unset or 0 (or lower), the setting
is not used, and the maximum number of ENIs is always equal to the maximum number for the instance type in question. Even when
MAX_ENI is a positive number, it is limited by the maximum number for the instance type.
Type: String
Default: DEBUG
Valid Values: DEBUG, INFO, WARN, ERROR, FATAL. (Not case sensitive)
Specifies the loglevel for ipamd.
Type: String
Default: /host/var/log/aws-routed-eni/ipamd.log
Valid Values: stdout or a file path
Specifies where to write the logging output of ipamd. Either to stdout or to override the default file (i.e., /var/log/aws-routed-eni/ipamd.log).
Type: String
Default: /var/log/aws-routed-eni/plugin.log
Valid Values: stderr or a file path
Specifies where to write the logging output for aws-cni plugin. Either to stderr or to override the default file (i.e., /var/log/aws-routed-eni/plugin.log).
Stdout cannot be supported for plugin log, please refer to #1248 for more details.
Note: If chaining an external plugin (i.e Cilium) that does not provide a pluginLogFile in its config file, the CNI plugin will by default write to os.Stderr. The output of cmdAdd are available in the Kubelet logs.
Type: String
Default: DEBUG
Valid Values: DEBUG, INFO, WARN, ERROR, FATAL. (Not case sensitive)
Specifies the loglevel for aws-cni plugin.
Type: String
Default: 127.0.0.1:61679
Specifies the bind address for the introspection endpoint.
A Unix Domain Socket can be specified with the unix: prefix before the socket path.
Type: Boolean as a String
Default: false
Specifies whether introspection endpoints are disabled on a worker node. Setting this to true will reduce the debugging
information we can get from the node when running the aws-cni-support.sh script.
Type: Boolean as a String
Default: false
Specifies whether the prometheus metrics endpoint is disabled or not for ipamd. By default metrics are published
on :61678/metrics.
Type: String
Default: eni
Specifies the veth prefix used to generate the host-side veth device name for the CNI. The prefix can be at most 4 characters long. The prefixes eth, vlan and lo are reserved by the CNI plugin and cannot be specified. We recommend using prefix name not shared by any other network interfaces on the worker node instance.
Type: String
Default: {}
Example values: {"tag_key": "tag_val"}
Metadata applied to ENI help you categorize and organize your resources for billing or other purposes. Each tag consists of a custom-defined key and an optional value. Tag keys can have a maximum character length of 128 characters. Tag values can have a maximum length of 256 characters. These tags will be added to all ENIs on the host.
Important: Custom tags should not contain k8s.amazonaws.com prefix as it is reserved. If the tag has k8s.amazonaws.com
string, tag addition will ignored.
Type: Boolean as a String
Default: true
Specifies whether ipamd should configure rp filter for primary interface. Setting this to false will require rp filter to be configured through init container
Type: String
Default: ""
Specifies the cluster name to tag allocated ENIs with. See the "Cluster Name tag" section below.
Type: Boolean as a String
Default: false
To enable security groups for pods you need to have at least an EKS 1.17 eks.3 cluster.
Setting ENABLE_POD_ENI to true will allow IPAMD to add the vpc.amazonaws.com/has-trunk-attached label to the node if the instance has capacity to attach an additional ENI.
The label notifies vpc-resource-controller (https://github.com/aws/amazon-vpc-resource-controller-k8s) to attach a Trunk ENI to the instance. The label value is initially set to false and is marked to true by IPAMD when vpc-resource-controller attaches a Trunk ENI to the instance. However, there might be cases where the label value will remain false if the instance doesn't support ENI Trunking.
Once enabled the VPC resource controller will then advertise branch network interfaces as extended resources on these nodes in your cluster. Branch interface capacity is additive to existing instance type limits for secondary IP addresses and prefixes. For example, a c5.4xlarge can continue to have up to 234 secondary IP addresses or 234 /28 prefixes assigned to standard network interfaces and up to 54 branch network interfaces. Each branch network interface only receives a single primary IP address and this IP address will be allocated to pods with security group(branch ENI pods).
Any of the WARM targets do not impact the scale of the branch ENI pods so you will have to set the WARM_{ENI/IP/PREFIX}_TARGET based on the number of non-branch ENI pods. If you are having the cluster mostly using pods with security group consider setting WARM_IP_TARGET to a very low value instead of default WARM_ENI_TARGET or WARM_PREFIX_TARGET to reduce wastage of IPs/ENIs.
NOTE! Toggling ENABLE_POD_ENI from true to false will not detach the Trunk ENI from instance. To delete/detach the Trunk ENI from instance, you need recycle the instance.
Type: Boolean as a String
Default: false
If ENABLE_POD_ENI is set to true, in order for the kubelet to connect via TCP (for liveness or readiness probes)
to pods that are using per pod security groups, DISABLE_TCP_EARLY_DEMUX should be set to true for amazon-k8s-cni-init
container under initcontainers. This will increase the local TCP connection latency slightly.
Details on why this is needed can be found in this #1212 comment.
To use this setting, a Linux kernel version of at least 4.6 is needed on the worker node.
You can use the below command to enable DISABLE_TCP_EARLY_DEMUX to true -
kubectl patch daemonset aws-node -n kube-system -p '{"spec": {"template": {"spec": {"initContainers": [{"env":[{"name":"DISABLE_TCP_EARLY_DEMUX","value":"true"}],"name":"aws-vpc-cni-init"}]}}}}'
Type: Boolean as a String
Default: false
To enable prefix delegation on nitro instances. Setting ENABLE_PREFIX_DELEGATION to true will start allocating a prefix (/28 for IPv4
and /80 for IPv6) instead of a secondary IP in the ENIs subnet. The total number of prefixes and private IP addresses will be less than the
limit on private IPs allowed by your instance. Setting or resetting of ENABLE_PREFIX_DELEGATION while pods are running or if ENIs are attached is supported and the new pods allocated will get IPs based on the mode of IPAMD but the max pods of kubelet should be updated which would need either kubelet restart or node recycle.
Setting ENABLE_PREFIX_DELEGATION to true will not increase the density of branch ENI pods. The limit on number of branch network interfaces per instance type will remain the same - https://docs.aws.amazon.com/eks/latest/userguide/security-groups-for-pods.html#supported-instance-types. Each branch network will be allocated a primary IP and this IP will be allocated for the branch ENI pods.
Please refer to VPC CNI Feature Matrix section below for additional information around using Prefix delegation with Custom Networking and Security Groups Per Pod features.
Note: ENABLE_PREFIX_DELEGATION needs to be set to true when VPC CNI is configured to operate in IPv6 mode (supported in v1.10.0+).
Type: Integer
Default: None
Specifies the number of free IPv4(/28) prefixes that the ipamd daemon should attempt to keep available for pod assignment on the node. Setting to a non-positive value is same as setting this to 0 or not setting the variable.
This environment variable works when ENABLE_PREFIX_DELEGATION is set to true and is overriden when WARM_IP_TARGET and MINIMUM_IP_TARGET are configured.
Type: Boolean as a String
Default: false
Setting DISABLE_NETWORK_RESOURCE_PROVISIONING to true will make IPAMD to depend only on IMDS to get attached ENIs and IPs/prefixes.
Type: Boolean as a String
Default: false
Setting ENABLE_BANDWIDTH_PLUGIN to true will update 10-aws.conflist to include upstream bandwidth plugin as a chained plugin.
Type: Boolean as a String
Default: false
Setting ANNOTATE_POD_IP to true will allow IPAMD to add an annotation vpc.amazonaws.com/pod-ips to the pod with pod IP.
There is a known issue with kubelet taking time to update Pod.Status.PodIP leading to calico being blocked on programming the policy. Setting ANNOTATE_POD_IP to true will enable AWS VPC CNI plugin to add Pod IP as an annotation to the pod spec to address this race condition.
To annotate the pod with pod IP, you will have to add "patch" permission for pods resource in aws-node clusterrole. You can use the below command -
cat << EOF > append.yaml
- apiGroups:
- ""
resources:
- pods
verbs:
- patch
EOF
kubectl apply -f <(cat <(kubectl get clusterrole aws-node -o yaml) append.yaml)
Type: Boolean as a String
Default: true
VPC CNI can operate in either IPv4 or IPv6 mode. Setting ENABLE_IPv4 to true will configure it in IPv4 mode (default mode).
Note: Dual stack mode isn't yet supported. So, enabling both IPv4 and IPv6 will be treated as invalid configuration.
Type: Boolean as a String
Default: false
VPC CNI can operate in either IPv4 or IPv6 mode. Setting ENABLE_IPv6 to true (both under aws-node and aws-vpc-cni-init containers in the manifest)
will configure it in IPv6 mode. IPv6 is only supported in Prefix Delegation mode, so ENABLE_PREFIX_DELEGATION needs to set to true if VPC CNI is
configured to operate in IPv6 mode. Prefix delegation is only supported on nitro instances.
Note: Please make sure that the required IPv6 IAM policy is applied (Refer to IAM Policy section above). Dual stack mode isn't yet supported. So, enabling both IPv4 and IPv6 will be treated as invalid configuration. Please refer to the VPC CNI Feature Matrix section below for additional information.
| IP Mode | Secondary IP Mode | Prefix Delegation | Security Groups Per Pod | WARM & MIN IP/Prefix Targets | External SNAT |
|---|---|---|---|---|---|
IPv4 |
Yes | Yes | Yes | Yes | Yes |
IPv6 |
No | Yes | No | No | No |
This plugin interacts with the following tags on ENIs:
cluster.k8s.amazonaws.com/namenode.k8s.amazonaws.com/instance_idnode.k8s.amazonaws.com/no_manage
The tag cluster.k8s.amazonaws.com/name will be set to the cluster name of the
aws-node daemonset which created the ENI.
The tag node.k8s.amazonaws.com/instance_id will be set to the instance ID of
the aws-node instance that allocated this ENI.
The tag node.k8s.amazonaws.com/no_manage is read by the aws-node daemonset to
determine whether an ENI attached to the machine should not be configured or
used for private IPs.
This tag is not set by the cni plugin itself, but rather may be set by a user to indicate that an ENI is intended for host networking pods, or for some other process unrelated to Kubernetes.
Note: Attaching an ENI with the no_manage tag will result in an incorrect
value for the Kubelet's --max-pods configuration option. Consider also
updating the MAX_ENI and --max-pods configuration options on this plugin
and the kubelet respectively if you are making use of this tag.
Currently IPAMD uses dockershim socket to pull pod sandboxes information upon its starting. The runtime can be set to others.
The mountPath should be changed to /var/run/cri.sock and hostPath should be pointed to the wanted socket, such as
/var/run/containerd/containerd.sock for containerd. If using helm chart, the flag --set cri.hostPath.path=/var/run/containerd/containerd.sock
can set the paths for you.
Note: When using other container runtime instead of dockershim, make sure also setting kubelet in instances.
L-IPAMD(aws-node daemonSet) running on every worker node requires access to kubernetes API server. If it can not reach
kubernetes API server, ipamd will exit and CNI will not be able to get any IP address for Pods. Here is a way to confirm if
aws-node has access to the kubernetes API server.
# find out kubernetes service IP, e.g. 10.0.0.1
kubectl get svc kubernetes
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 29d
# ssh into worker node, check if worker node can reach API server
telnet 10.0.0.1 443
Trying 10.0.0.1...
Connected to 10.0.0.1.
Escape character is '^]'. <-------- kubernetes API server is reachable
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