mdaisuke/kube-node-init

Kubernetes daemonset for node initial configuration. Currently for modifying files and systemd services on eksctl nodes without changing userdata

kube-node-init

kube-node-init is a Kubernetes daemonset for node initial configuration including:

• Write files
• Restart systemd services
• Customize kernel parameters
• Add Kubernetes node labels
• Add Kubernetes node taints

Getting Started

$ helm repo add kube-node-init-charts https://raw.githubusercontent.com/mumoshu/kube-node-init/master/docs
$ helm install --name kube-node-init kube-node-init-charts/kube-node-init

This installs the followings to your nodes:

• The init script
• Kernel parameters

You can customze every aspect of kube-node-init via values.yaml. Please read the chart's README for more configuration options.

The init script

The default script does the following to improve your EKS nodes runnin Amazon Linux 2:

• Installs a tweaked /etc/chrony.conf and then restarts chrony systemd service. The conf includes allow 127.0.0.1/32, so that Prometheus node-exporter's ntp-collector is able to connect the chronyd running on the node.

Customizing the init script

You can create your own values.yaml as follows to let kube-node-init use your own script:

values.yaml:

script: |
  echo your alternative, bespoke node init script here!

Run helm upgrade to let kube-node-init rerun with your script:

$ helm upgrade --name kube-node-init stable/kube-node-init --values values.yaml

Kernel parameters

kube-node-init also tweaks several kernel parameters listed under the sysctl.params key in the default values.yaml:

# default: 128
net.core.somaxconn: 65535
# default: 256
net.ipv4.tcp_max_syn_backlog: 65535
# dfault: 1000
net.core.netdev_max_backlog: 16384
# default: 32768 60999
net.ipv4.ip_local_port_range: 1024 65535
# default: 0
# enable(1) to optimize against short-lived sessions
net.ipv4.tcp_tw_reuse: 1
# default: 7200
net.ipv4.tcp_keepalive_time: 200
# default: 75
net.ipv4.tcp_keepalive_intvl: 60
# default: 9
net.ipv4.tcp_keepalive_probes: 3
# default: 6
net.ipv4.tcp_syn_retries: 5

In case you want to disable this feature, set --set sysctl.enabled=true while installing the chart.