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cluster.md

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Cluster configuration

CKE deploys and maintains a Kubernetes cluster and an etcd cluster solely for the Kubernetes cluster. The configurations of the clusters can be defined by a YAML or JSON object with these fields:

Name Required Type Description
name true string The k8s cluster name.
nodes true array Node list.
taint_control_plane false bool If true, taint control plane nodes.
control_plane_tolerations false array List of tolerated taint keys for control plane.
service_subnet true string CIDR subnet for k8s Service.
dns_servers false array List of upstream DNS server IP addresses.
dns_service false string Upstream DNS service name with namespace as namespace/service.
reboot false Reboot See Reboot.
repair false Repair See Repair.
options false Options See Options.
  • control_plane_tolerations is used in sabakan integration.
  • Upstream DNS servers can be specified one of the following ways:
    • List server IP addresses in dns_servers.
    • Specify Kubernetes Service name in dns_service (e.g. "kube-system/dns").
      The service type must be ClusterIP.

Node

A Node has these fields:

Name Required Type Description
address true string IP address of the node.
hostname false string Override the real hostname of the node in k8s.
user true string SSH user name.
control_plane false bool If true, the node will be used for k8s control plane and etcd.
annotations false object Node annotations.
labels false object Node labels.
taints false []Taint Node taints.

annotations, labels, and taints are added or updated, but not removed. This is because other applications may edit their own annotations, labels, or taints.

Note that annotations, labels, and taints whose names contain cke.cybozu.com/ or start with node-role.kubernetes.io/ are reserved for CKE internal usage, therefore should not be used.

Taint

Name Required Type Description
key true string The taint key to be applied to a node.
value false string The taint value corresponding to the taint key.
effect true string NoSchedule, PreferNoSchedule or NoExecute.

Reboot

Name Required Type Description
reboot_command true array A command to reboot. List of strings.
boot_check_command true array A command to check nodes booted. List of strings.
eviction_timeout_seconds false *int Deadline for eviction. Must be positive. Default: 600 (10 minutes).
command_timeout_seconds false *int Deadline for rebooting. Zero means infinity. Default: wait indefinitely
command_retries false *int Number of reboot retries, not including initial attempt. Default: 0
command_interval false *int Interval of time between reboot retries in seconds. Default: 0
evict_retries false *int Number of eviction retries, not including initial attempt. Default: 0
evict_interval false *int Interval of time between eviction retries in seconds. Default: 0
max_concurrent_reboots false *int Maximum number of nodes to be rebooted concurrently. Default: 1
protected_namespaces false LabelSelector A label selector to protect namespaces.

reboot_command is the command to reboot a node. The node is passed as a command argument. The command should return zero if the reboot is successfully started. If command_timeout_seconds is specified, the reboot command should return within command_timeout_seconds seconds, or it is considered failed. If the reboot command has failed, CKE retries it for command_retries times with command_interval-second interval.

boot_check_command is the command to check a node booted. The node and the unix time when the reboot command is run are passed as command arguments. If the node is successfully booted, this command should output true to stdout and the exit status should be zero. If the node is not booted yet, this command should output false to stdout and the exit status should be zero. If command_timeout_seconds is specified, the check command should return within command_timeout_seconds seconds, or it is considered failed.

CKE tries to delete Pods in the protected_namespaces gracefully with the Kubernetes eviction API. If the eviction API has failed, CKE retries it for evict_retries times with evict_interval-second interval. If any of the Pods cannot be deleted, it aborts the operation.

The Pods in the non-protected namespaces are also tried to be deleted gracefully with the Kubernetes eviction API, but they would be simply deleted if eviction is denied.

If protected_namespaces is not given, all namespaces are protected.

Repair

Name Required Type Description
repair_procedures true []RepairProcedure List of repair procedures.
max_concurrent_repairs false *int Maximum number of machines to be repaired concurrently. Default: 1
protected_namespaces false LabelSelector A label selector to protect namespaces.
evict_retries false *int Number of eviction retries, not including initial attempt. Default: 0
evict_interval false *int Number of time between eviction retries in seconds. Default: 0
eviction_timeout_seconds false *int Deadline for eviction. Must be positive. Default: 600 (10 minutes)

The repair configurations control the repair functionality.

RepairProcedure

Name Required Type Description
machine_types true array Type names of the target machines to be repaired by this procedure. List of strings.
repair_operations true []RepairOperation List of repair operations.

RepairOperation

Name Required Type Description
operation true string Name of repair operation.
repair_steps true []RepairStep Sequences of repair steps.
health_check_command true array A command to check repaired machine's health. List of strings.
command_timeout_seconds false *int Deadline for health retrieval. Zero means infinity. Default: 30
success_command false array A command executed when repair succeeded. List of strings.
success_command_timeout false *int Deadline for execution of succcess_command. Zero means infinity. Default: 30
RepairStep
Name Required Type Description
repair_command true array A command and its arguments to repair the target machine. List of strings.
command_timeout_seconds false *int Deadline for repairing. Zero means infinity. Default: 30
command_retries false *int Number of repair retries, not including initial attempt. Default: 0
command_interval false *int Interval of time between repair retries in seconds. Default: 0
need_drain false bool If true, perform drain of Pods on the target machine prior to the execution of the repair command. Default: false
watch_seconds false *int Follow-up duration in seconds to watch whether the machine becomes healthy after the execution of the repair command. Default: 0

Options

Option is a set of optional parameters for k8s components.

Name Required Type Description
etcd false EtcdParams Extra arguments for etcd.
etcd-rivers false ServiceParams Extra arguments for EtcdRivers.
rivers false ServiceParams Extra arguments for Rivers.
kube-api false APIServerParams Extra arguments for API server.
kube-controller-manager false ServiceParams Extra arguments for controller manager.
kube-scheduler false SchedulerParams Extra arguments for scheduler.
kube-proxy false ProxyParams Extra arguments for kube-proxy.
kubelet false KubeletParams Extra arguments for kubelet.

ServiceParams

Name Required Type Description
extra_args false array Extra command-line arguments. List of strings.
extra_binds false array Extra bind mounts. List of Mount.
extra_env false object Extra environment variables.

Mount

Name Required Type Description
source true string Path in a host to a directory or a file.
destination true string Path in the container filesystem.
read_only false bool True to mount the directory or file as read-only.
propagation false string Whether mounts can be propagated to replicas.
selinux_label false string Relabel the SELinux label of the host directory.

selinux-label:

  • If SELinux is not in enforcing mode, it will not set the SELinux label.
  • "z": The mount content is shared among multiple containers.
  • "Z": The mount content is private and unshared.
  • This label should not be specified to system directories.

EtcdParams

Name Required Type Description
volume_name false string Docker volume name for data. Default: etcd-cke.
extra_args false array Extra command-line arguments. List of strings.
extra_binds false array Extra bind mounts. List of Mount.
extra_env false object Extra environment variables.

APIServerParams

Name Required Type Description
audit_log_enabled false bool If true, audit log will be logged to the specified path.
audit_log_policy false string Audit policy configuration in yaml format.
audit_log_path false string Audit log output path. Default is standard output.
extra_args false array Extra command-line arguments. List of strings.
extra_binds false array Extra bind mounts. List of Mount.
extra_env false object Extra environment variables.

ProxyParams

Name Required Type Description
config false *v1alpha1.KubeProxyConfiguration See below.
disable false bool If true, CKE will skip to install kube-proxy.
extra_args false array Extra command-line arguments. List of strings.
extra_binds false array Extra bind mounts. List of Mount.
extra_env false object Extra environment variables.

config must be a partial v1alpha1.KubeProxyConfiguration. Fields in the below table have default values:

Name Value
HostnameOverride Host name or address if the host name is empty
MetricsBindAddress 0.0.0.0
KubeProxyConntrackConfiguration.TCPEstablishedTimeout 24h
KubeProxyConntrackConfiguration.TCPCloseWaitTimeout 1h

ClientConnection.Kubeconfig is managed by CKE and are not configurable. Changing KubeProxyConfiguration.Mode requires full node restarts.

KubeletParams

Name Required Type Description
boot_taints false []Taint Bootstrap node taints.
cni_conf_file false CNIConfFile CNI configuration file.
config false *v1beta1.KubeletConfiguration See below.
cri_endpoint false string Path of the runtime socket. Default: /run/containerd/containerd.sock.
extra_args false array Extra command-line arguments. List of strings.
extra_binds false array Extra bind mounts. List of Mount.
extra_env false object Extra environment variables.

Boot taints

Taints in boot_taints are added to a Node in the following cases:

  • when that Node is registered with Kubernetes by kubelet, or
  • when kubelet on that Node is being booted while the Node resource is already registered.

Those taints can be removed manually when they are no longer needed. Note that the second case happens when the physical node is rebooted without resource manipulation. If you want to add taints only at Node registration, use RegisterWithTaints field in KubeletConfiguration.

KubeletConfiguration

config must be a partial v1beta1.KubeletConfiguration.

Fields that are described as This field should not be updated without a full node reboot. won't be updated on the running node for safety. Such fields include CgroupDriver or QOSReserved.

Fields in the below table have default values:

Name Value
ClusterDomain cluster.local
RuntimeRequestTimeout 15m
HealthzBindAddress 0.0.0.0
VolumePluginDir /opt/volume/bin

TLSCertFile, TLSPrivateKeyFile, Authentication, Authorization, and ClusterDNS are managed by CKE and are not configurable. RegisterWithTaints is managed by CKE when boot_taints exists in KubeletParams. When taints with the same key are specified in both boot_taints (KubeletParams) and RegisterWithTaints (KubeletConfiguration), CKE respects boot_taints.

CNIConfFile

CNI configuration file specified by cni_conf_file will be put in /etc/cni/net.d directory on all nodes. The file is created only when kubelet starts on the node; it will not be updated later on.

Name Required Type Description
name true string file name
content true string file content in JSON format

name is the filename of CNI configuration file. It should end with either .conf or .conflist.

SchedulerParams

Name Required Type Description
config false *v1.KubeSchedulerConfiguration See below.
extra_args false array Extra command-line arguments. List of strings.
extra_binds false array Extra bind mounts. List of Mount.
extra_env false object Extra environment variables.

config must be a partial v1.KubeSchedulerConfiguration.

Fields in config may have default values. Some fields are overwritten by CKE. Please see the source code for more details.