Configurable Parameters in Kubespray

Generic Ansible variables

You can view facts gathered by Ansible automatically here.

Some variables of note include:

ansible_user: user to connect to via SSH
ansible_default_ipv4.address: IP address Ansible automatically chooses. Generated based on the output from the command ip -4 route get 8.8.8.8

Common vars that are used in Kubespray

calico_version - Specify version of Calico to use
calico_cni_version - Specify version of Calico CNI plugin to use
docker_version - Specify version of Docker to used (should be quoted string)
etcd_version - Specify version of ETCD to use
ipip - Enables Calico ipip encapsulation by default
hyperkube_image_repo - Specify the Docker repository where Hyperkube resides
hyperkube_image_tag - Specify the Docker tag where Hyperkube resides
kube_network_plugin - Sets k8s network plugin (default Calico)
kube_proxy_mode - Changes k8s proxy mode to iptables mode
kube_version - Specify a given Kubernetes hyperkube version
searchdomains - Array of DNS domains to search when looking up hostnames
nameservers - Array of nameservers to use for DNS lookup

Addressing variables

ip - IP to use for binding services (host var)
access_ip - IP for other hosts to use to connect to. Often required when deploying from a cloud, such as OpenStack or GCE and you have separate public/floating and private IPs.
ansible_default_ipv4.address - Not Kubespray-specific, but it is used if ip and access_ip are undefined
loadbalancer_apiserver - If defined, all hosts will connect to this address instead of localhost for kube-masters and kube-master[0] for kube-nodes. See more details in the HA guide.
loadbalancer_apiserver_localhost - makes all hosts to connect to the apiserver internally load balanced endpoint. Mutual exclusive to the loadbalancer_apiserver. See more details in the HA guide.

Cluster variables

Kubernetes needs some parameters in order to get deployed. These are the following default cluster paramters:

cluster_name - Name of cluster (default is cluster.local)
domain_name - Name of cluster DNS domain (default is cluster.local)
kube_network_plugin - Plugin to use for container networking
kube_service_addresses - Subnet for cluster IPs (default is 10.233.0.0/18). Must not overlap with kube_pods_subnet
kube_pods_subnet - Subnet for Pod IPs (default is 10.233.64.0/18). Must not overlap with kube_service_addresses.
kube_network_node_prefix - Subnet allocated per-node for pod IPs. Remainin bits in kube_pods_subnet dictates how many kube-nodes can be in cluster.
dns_setup - Enables dnsmasq
dns_server - Cluster IP for dnsmasq (default is 10.233.0.2)
skydns_server - Cluster IP for KubeDNS (default is 10.233.0.3)
cloud_provider - Enable extra Kubelet option if operating inside GCE or OpenStack (default is unset)
kube_hostpath_dynamic_provisioner - Required for use of PetSets type in Kubernetes

Note, if cloud providers have any use of the 10.233.0.0/16, like instances' private addresses, make sure to pick another values for kube_service_addresses and kube_pods_subnet, for example from the 172.18.0.0/16.

DNS variables

By default, dnsmasq gets set up with 8.8.8.8 as an upstream DNS server and all other settings from your existing /etc/resolv.conf are lost. Set the following variables to match your requirements.

upstream_dns_servers - Array of upstream DNS servers configured on host in addition to Kubespray deployed DNS
nameservers - Array of DNS servers configured for use in dnsmasq
searchdomains - Array of up to 4 search domains
skip_dnsmasq - Don't set up dnsmasq (use only KubeDNS)

For more information, see DNS Stack.

Other service variables

docker_options - Commonly used to set --insecure-registry=myregistry.mydomain:5000
http_proxy/https_proxy/no_proxy - Proxy variables for deploying behind a proxy
kubelet_load_modules - For some things, kubelet needs to load kernel modules. For example, dynamic kernel services are needed for mounting persistent volumes into containers. These may not be loaded by preinstall kubernetes processes. For example, ceph and rbd backed volumes. Set this variable to true to let kubelet load kernel modules.

Custom flags for Kube Components

For all kube components, custom flags can be passed in. This allows for edge cases where users need changes to the default deployment that may not be applicable to all deployments. This can be done by providing a list of flags. Example:

kubelet_custom_flags:
  - "--eviction-hard=memory.available<100Mi"
  - "--eviction-soft-grace-period=memory.available=30s"
  - "--eviction-soft=memory.available<300Mi"

The possible vars are:

apiserver_custom_flags
controller_mgr_custom_flags
scheduler_custom_flags
kubelet_custom_flags

User accounts

Kubespray sets up two Kubernetes accounts by default: root and kube. Their passwords default to changeme. You can set this by changing kube_api_pwd.

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