# Configurable Parameters in Kubespray

## Generic Ansible variables

You can view facts gathered by Ansible automatically
[here](https://docs.ansible.com/ansible/latest/user_guide/playbooks_vars_facts.html#ansible-facts).

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 use (should be quoted
  string). Must match one of the keys defined for *docker_versioned_pkg*
  in `roles/container-engine/docker/vars/*.yml`.
* *containerd_version* - Specify version of containerd to use when setting `container_manager` to `containerd`
* *docker_containerd_version* - Specify which version of containerd to use when setting `container_manager` to `docker`
* *etcd_version* - Specify version of ETCD to use
* *calico_ipip_mode* - Configures Calico ipip encapsulation - valid values are 'Never', 'Always' and 'CrossSubnet' (default 'Never')
* *calico_vxlan_mode* - Configures Calico vxlan encapsulation - valid values are 'Never', 'Always' and 'CrossSubnet' (default 'Always')
* *calico_network_backend* - Configures Calico network backend - valid values are 'none', 'bird' and 'vxlan' (default 'vxlan')
* *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 version
* *searchdomains* - Array of DNS domains to search when looking up hostnames
* *remove_default_searchdomains* - Boolean that removes the default searchdomain
* *nameservers* - Array of nameservers to use for DNS lookup
* *preinstall_selinux_state* - Set selinux state, permitted values are permissive, enforcing and disabled.

## 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
* *ip6* - IPv6 address to use for binding services. (host var)
  If *enable_dual_stack_networks* is set to ``true`` and *ip6* is defined,
  kubelet's ``--node-ip`` and node's ``InternalIP`` will be the combination of *ip* and *ip6*.
* *loadbalancer_apiserver* - If defined, all hosts will connect to this
  address instead of localhost for kube_control_planes and kube_control_plane[0] for
  kube_nodes. See more details in the
  [HA guide](/docs/ha-mode.md).
* *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](/docs/ha-mode.md).

## Cluster variables

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

* *cluster_name* - Name of cluster (default is cluster.local)

* *container_manager* - Container Runtime to install in the nodes (default is containerd)

* *image_command_tool* - Tool used to pull images (default depends on `container_manager`
  and is `nerdctl` for `containerd`, `crictl` for `crio`, `docker` for `docker`)

* *image_command_tool_on_localhost* - Tool used to pull images on localhost
  (default is equal to `image_command_tool`)

* *dns_domain* - 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. Remaining
  bits in kube_pods_subnet dictates how many kube_nodes can be in cluster. Setting this > 25 will
  raise an assertion in playbooks if the `kubelet_max_pods` var also isn't adjusted accordingly
  (assertion not applicable to calico which doesn't use this as a hard limit, see
  [Calico IP block sizes](https://docs.projectcalico.org/reference/resources/ippool#block-sizes)).

* *enable_dual_stack_networks* - Setting this to true will provision both IPv4 and IPv6 networking for pods and services.

* *kube_service_addresses_ipv6* - Subnet for cluster IPv6 IPs (default is ``fd85:ee78:d8a6:8607::1000/116``). Must not overlap with ``kube_pods_subnet_ipv6``.

* *kube_pods_subnet_ipv6* - Subnet for Pod IPv6 IPs (default is ``fd85:ee78:d8a6:8607::1:0000/112``). Must not overlap with ``kube_service_addresses_ipv6``.

* *kube_network_node_prefix_ipv6* - Subnet allocated per-node for pod IPv6 IPs. Remaining bits in ``kube_pods_subnet_ipv6`` dictates how many kube_nodes can be in cluster.

* *skydns_server* - Cluster IP for DNS (default is 10.233.0.3)

* *skydns_server_secondary* - Secondary Cluster IP for CoreDNS used with coredns_dual deployment (default is 10.233.0.4)

* *enable_coredns_k8s_external* - If enabled, it configures the [k8s_external plugin](https://coredns.io/plugins/k8s_external/)
  on the CoreDNS service.

* *coredns_k8s_external_zone* - Zone that will be used when CoreDNS k8s_external plugin is enabled
  (default is k8s_external.local)

* *enable_coredns_k8s_endpoint_pod_names* - If enabled, it configures endpoint_pod_names option for kubernetes plugin.
  on the CoreDNS service.

* *cloud_provider* - Enable extra Kubelet option if operating inside GCE or
  OpenStack (default is unset)

* *kube_feature_gates* - A list of key=value pairs that describe feature gates for
  alpha/experimental Kubernetes features. (defaults is `[]`).
  Additionally, you can use also the following variables to individually customize your kubernetes components installation (they works exactly like `kube_feature_gates`):
  * *kube_apiserver_feature_gates*
  * *kube_controller_feature_gates*
  * *kube_scheduler_feature_gates*
  * *kube_proxy_feature_gates*
  * *kubelet_feature_gates*

* *kubeadm_feature_gates* - A list of key=value pairs that describe feature gates for
  alpha/experimental Kubeadm features. (defaults is `[]`)

* *authorization_modes* - A list of [authorization mode](
  https://kubernetes.io/docs/reference/access-authn-authz/authorization/#using-flags-for-your-authorization-module)
  that the cluster should be configured for. Defaults to `['Node', 'RBAC']`
  (Node and RBAC authorizers).
  Note: `Node` and `RBAC` are enabled by default. Previously deployed clusters can be
  converted to RBAC mode. However, your apps which rely on Kubernetes API will
  require a service account and cluster role bindings. You can override this
  setting by setting authorization_modes to `[]`.

* *kube_apiserver_admission_control_config_file* - Enable configuration for `kube-apiserver` admission plugins.
  Currently this variable allow you to configure the `EventRateLimit` admission plugin.

  To configure the **EventRateLimit** plugin you have to define a data structure like this:

```yml
kube_apiserver_admission_event_rate_limits:
  limit_1:
    type: Namespace
    qps: 50
    burst: 100
    cache_size: 2000
  limit_2:
    type: User
    qps: 50
    burst: 100
  ...
```

* *kube_apiserver_service_account_lookup* - Enable validation service account before validating token. Default `true`.

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``.

## Enabling Dual Stack (IPV4 + IPV6) networking

If *enable_dual_stack_networks* is set to ``true``, Dual Stack networking will be enabled in the cluster. This will use the default IPv4 and IPv6 subnets specified in the defaults file in the ``kubespray-defaults`` role, unless overridden of course. The default config will give you room for up to 256 nodes with 126 pods per node, and up to 4096 services.

## DNS variables

By default, hosts are 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 by hosts
* *searchdomains* - Array of up to 4 search domains
* *remove_default_searchdomains* - Boolean. If enabled, `searchdomains` variable can hold 6 search domains.
* *dns_etchosts* - Content of hosts file for coredns and nodelocaldns
* *dns_upstream_forward_extra_opts* - Options to add in the forward section of coredns/nodelocaldns related to upstream DNS servers

For more information, see [DNS
Stack](https://github.com/kubernetes-sigs/kubespray/blob/master/docs/dns-stack.md).

## Other service variables

* *docker_options* - Commonly used to set
  ``--insecure-registry=myregistry.mydomain:5000``

* *docker_plugins* - This list can be used to define [Docker plugins](https://docs.docker.com/engine/extend/) to install.

* *containerd_default_runtime* - If defined, changes the default Containerd runtime used by the Kubernetes CRI plugin.

* *containerd_additional_runtimes* - Sets the additional Containerd runtimes used by the Kubernetes CRI plugin.
  [Default config](https://github.com/kubernetes-sigs/kubespray/blob/master/roles/container-engine/containerd/defaults/main.yml) can be overridden in inventory vars.

* *crio_criu_support_enabled* - When set to `true`, enables the container checkpoint/restore in CRI-O. It's required to install [CRIU](https://criu.org/Installation) on the host when dumping/restoring checkpoints. And it's recommended to enable the feature gate `ContainerCheckpoint` so that the kubelet get a higher level API to simplify the operations (**Note**: It's still in experimental stage, just for container analytics so far). You can follow the [documentation](https://kubernetes.io/blog/2022/12/05/forensic-container-checkpointing-alpha/).

* *http_proxy/https_proxy/no_proxy/no_proxy_exclude_workers/additional_no_proxy* - Proxy variables for deploying behind a
  proxy. Note that no_proxy defaults to all internal cluster IPs and hostnames
  that correspond to each node.

* *kubelet_cgroup_driver* - Allows manual override of the cgroup-driver option for Kubelet.
  By default autodetection is used to match container manager configuration.
  `systemd` is the preferred driver for `containerd` though it can have issues with `cgroups v1` and `kata-containers` in which case you may want to change to `cgroupfs`.

* *kubelet_rotate_certificates* - Auto rotate the kubelet client certificates by requesting new certificates
  from the kube-apiserver when the certificate expiration approaches.

* *kubelet_rotate_server_certificates* - Auto rotate the kubelet server certificates by requesting new certificates
  from the kube-apiserver when the certificate expiration approaches.
  Note that enabling this also activates *kubelet_csr_approver* which approves automatically the CSRs.
  To customize its behavior, you can override the Helm values via *kubelet_csr_approver_values*.
  See [kubelet-csr-approver](https://github.com/postfinance/kubelet-csr-approver) for more information.

* *kubelet_streaming_connection_idle_timeout* - Set the maximum time a streaming connection can be idle before the connection is automatically closed.

* *kubelet_image_gc_high_threshold* - Set the percent of disk usage after which image garbage collection is always run.
  The percent is calculated by dividing this field value by 100, so this field must be between 0 and 100, inclusive.
  When specified, the value must be greater than imageGCLowThresholdPercent. Default: 85

* *kubelet_image_gc_low_threshold* - Set the percent of disk usage before which image garbage collection is never run.
  Lowest disk usage to garbage collect to.
  The percent is calculated by dividing this field value by 100, so the field value must be between 0 and 100, inclusive.
  When specified, the value must be less than imageGCHighThresholdPercent. Default: 80

* *kubelet_make_iptables_util_chains* - If `true`, causes the kubelet ensures a set of `iptables` rules are present on host.

* *kubelet_cpu_manager_policy* -  If set to `static`, allows pods with certain resource characteristics to be granted increased CPU affinity and exclusivity on the node. And it should be set with `kube_reserved` or `system-reserved`, enable this with the following guide:[Control CPU Management Policies on the Node](https://kubernetes.io/docs/tasks/administer-cluster/cpu-management-policies/)

* *kubelet_topology_manager_policy* - Control the behavior of the allocation of CPU and Memory from different [NUMA](https://en.wikipedia.org/wiki/Non-uniform_memory_access) Nodes. Enable this with the following guide: [Control Topology Management Policies on a node](https://kubernetes.io/docs/tasks/administer-cluster/topology-manager).

* *kubelet_topology_manager_scope* - The Topology Manager can deal with the alignment of resources in a couple of distinct scopes: `container` and `pod`. See [Topology Manager Scopes](https://kubernetes.io/docs/tasks/administer-cluster/topology-manager/#topology-manager-scopes).

* *kubelet_systemd_hardening* - If `true`, provides kubelet systemd service with security features for isolation.

  **N.B.** To enable this feature, ensure you are using the **`cgroup v2`** on your system. Check it out with command: `sudo ls -l /sys/fs/cgroup/*.slice`. If directory does not exist, enable this with the following guide: [enable cgroup v2](https://rootlesscontaine.rs/getting-started/common/cgroup2/#enabling-cgroup-v2).

  * *kubelet_secure_addresses* - By default *kubelet_systemd_hardening* set the **control plane** `ansible_host` IPs as the `kubelet_secure_addresses`. In case you have multiple interfaces in your control plane nodes and the `kube-apiserver` is not bound to the default interface, you can override them with this variable.
    Example:

    The **control plane** node may have 2 interfaces with the following IP addresses: `eth0:10.0.0.110`, `eth1:192.168.1.110`.

    By default the `kubelet_secure_addresses` is set with the `10.0.0.110` the ansible control host uses `eth0` to  connect to the machine. In case you want to use `eth1` as the outgoing interface on which `kube-apiserver` connects to the `kubelet`s, you should override the variable in this way: `kubelet_secure_addresses: "192.168.1.110"`.

* *node_labels* - Labels applied to nodes via `kubectl label node`.
  For example, labels can be set in the inventory as variables or more widely in group_vars.
  *node_labels* can only be defined as a dict:

```yml
node_labels:
  label1_name: label1_value
  label2_name: label2_value
```

* *node_taints* - Taints applied to nodes via `kubectl taint node`.
  For example, taints can be set in the inventory as variables or more widely in group_vars.
  *node_taints* has to be defined as a list of strings in format `key=value:effect`, e.g.:

```yml
node_taints:
  - "node.example.com/external=true:NoSchedule"
```

* *kubernetes_audit* - When set to `true`, enables Auditing.
  The auditing parameters can be tuned via the following variables (which default values are shown below):
  * `audit_log_path`: /var/log/audit/kube-apiserver-audit.log
  * `audit_log_maxage`: 30
  * `audit_log_maxbackups`: 10
  * `audit_log_maxsize`: 100
  * `audit_policy_file`: "{{ kube_config_dir }}/audit-policy/apiserver-audit-policy.yaml"

  By default, the `audit_policy_file` contains [default rules](https://github.com/kubernetes-sigs/kubespray/blob/master/roles/kubernetes/control-plane/templates/apiserver-audit-policy.yaml.j2) that can be overridden with the `audit_policy_custom_rules` variable.
* *kubernetes_audit_webhook* - When set to `true`, enables the webhook audit backend.
  The webhook parameters can be tuned via the following variables (which default values are shown below):
  * `audit_webhook_config_file`: "{{ kube_config_dir }}/audit-policy/apiserver-audit-webhook-config.yaml"
  * `audit_webhook_server_url`: `"https://audit.app"`
  * `audit_webhook_server_extra_args`: {}
  * `audit_webhook_mode`: batch
  * `audit_webhook_batch_max_size`: 100
  * `audit_webhook_batch_max_wait`: 1s
* *kubectl_alias* - Bash alias of kubectl to interact with Kubernetes cluster much easier.

### 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.

Extra flags for the kubelet can be specified using these variables,
in the form of dicts of key-value pairs of configuration parameters that will be inserted into the kubelet YAML config file. The `kubelet_node_config_extra_args` apply kubelet settings only to nodes and not control planes. Example:

```yml
kubelet_config_extra_args:
  evictionHard:
    memory.available: "100Mi"
  evictionSoftGracePeriod:
    memory.available: "30s"
  evictionSoft:
    memory.available: "300Mi"
```

The possible vars are:

* *kubelet_config_extra_args*
* *kubelet_node_config_extra_args*

Previously, the same parameters could be passed as flags to kubelet binary with the following vars:

* *kubelet_custom_flags*
* *kubelet_node_custom_flags*

The `kubelet_node_custom_flags` apply kubelet settings only to nodes and not control planes. Example:

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

This alternative is deprecated and will remain until the flags are completely removed from kubelet

Extra flags for the API server, controller, and scheduler components can be specified using these variables,
in the form of dicts of key-value pairs of configuration parameters that will be inserted into the kubeadm YAML config file:

* *kube_kubeadm_apiserver_extra_args*
* *kube_kubeadm_controller_extra_args*
* *kube_kubeadm_scheduler_extra_args*

## App variables

* *helm_version* - Only supports v3.x. Existing v2 installs (with Tiller) will not be modified and need to be removed manually.
