# Ansible variables ## Inventory The inventory is composed of 3 groups: * **kube_node** : list of kubernetes nodes where the pods will run. * **kube_control_plane** : list of servers where kubernetes control plane components (apiserver, scheduler, controller) will run. * **etcd**: list of servers to compose the etcd server. You should have at least 3 servers for failover purpose. Note: do not modify the children of _k8s_cluster_, like putting the _etcd_ group into the _k8s_cluster_, unless you are certain to do that and you have it fully contained in the latter: ```ShellSession k8s_cluster ⊂ etcd => kube_node ∩ etcd = etcd ``` When _kube_node_ contains _etcd_, you define your etcd cluster to be as well schedulable for Kubernetes workloads. If you want it a standalone, make sure those groups do not intersect. If you want the server to act both as control-plane and node, the server must be defined on both groups _kube_control_plane_ and _kube_node_. If you want a standalone and unschedulable control plane, the server must be defined only in the _kube_control_plane_ and not _kube_node_. There are also two special groups: * **calico_rr** : explained for [advanced Calico networking cases](/docs/calico.md) * **bastion** : configure a bastion host if your nodes are not directly reachable Below is a complete inventory example: ```ini ## Configure 'ip' variable to bind kubernetes services on a ## different ip than the default iface node1 ansible_host=95.54.0.12 ip=10.3.0.1 node2 ansible_host=95.54.0.13 ip=10.3.0.2 node3 ansible_host=95.54.0.14 ip=10.3.0.3 node4 ansible_host=95.54.0.15 ip=10.3.0.4 node5 ansible_host=95.54.0.16 ip=10.3.0.5 node6 ansible_host=95.54.0.17 ip=10.3.0.6 [kube_control_plane] node1 node2 [etcd] node1 node2 node3 [kube_node] node2 node3 node4 node5 node6 [k8s_cluster:children] kube_node kube_control_plane ``` ## Group vars and overriding variables precedence The group variables to control main deployment options are located in the directory ``inventory/sample/group_vars``. Optional variables are located in the `inventory/sample/group_vars/all.yml`. Mandatory variables that are common for at least one role (or a node group) can be found in the `inventory/sample/group_vars/k8s_cluster.yml`. There are also role vars for docker, kubernetes preinstall and control plane roles. According to the [ansible docs](https://docs.ansible.com/ansible/latest/playbooks_variables.html#variable-precedence-where-should-i-put-a-variable), those cannot be overridden from the group vars. In order to override, one should use the `-e` runtime flags (most simple way) or other layers described in the docs. Kubespray uses only a few layers to override things (or expect them to be overridden for roles): Layer | Comment ------|-------- **role defaults** | provides best UX to override things for Kubespray deployments inventory vars | Unused **inventory group_vars** | Expects users to use ``all.yml``,``k8s_cluster.yml`` etc. to override things inventory host_vars | Unused playbook group_vars | Unused playbook host_vars | Unused **host facts** | Kubespray overrides for internal roles' logic, like state flags play vars | Unused play vars_prompt | Unused play vars_files | Unused registered vars | Unused set_facts | Kubespray overrides those, for some places **role and include vars** | Provides bad UX to override things! Use extra vars to enforce block vars (only for tasks in block) | Kubespray overrides for internal roles' logic task vars (only for the task) | Unused for roles, but only for helper scripts **extra vars** (always win precedence) | override with ``ansible-playbook -e @foo.yml`` ## Ansible tags The following tags are defined in playbooks: | Tag name | Used for |--------------------------------|--------- | ambassador | Ambassador Ingress Controller | annotate | Create kube-router annotation | apps | K8s apps definitions | asserts | Check tasks for download role | aws-ebs-csi-driver | Configuring csi driver: aws-ebs | azure-csi-driver | Configuring csi driver: azure | bastion | Setup ssh config for bastion | bootstrap-os | Anything related to host OS configuration | calico | Network plugin Calico | calico_rr | Configuring Calico route reflector | canal | Network plugin Canal | cephfs-provisioner | Configuring CephFS | cert-manager | Configuring certificate manager for K8s | cilium | Network plugin Cilium | cinder-csi-driver | Configuring csi driver: cinder | client | Kubernetes clients role | cloud-provider | Cloud-provider related tasks | cluster-roles | Configuring cluster wide application (psp ...) | cni | CNI plugins for Network Plugins | containerd | Configuring containerd engine runtime for hosts | container_engine_accelerator | Enable nvidia accelerator for runtimes | container-engine | Configuring container engines | container-runtimes | Configuring container runtimes | coredns | Configuring coredns deployment | crio | Configuring crio container engine for hosts | crun | Configuring crun runtime | csi-driver | Configuring csi driver | dashboard | Installing and configuring the Kubernetes Dashboard | dns | Remove dns entries when resetting | docker | Configuring docker engine runtime for hosts | download | Fetching container images to a delegate host | etcd | Configuring etcd cluster | etcd-secrets | Configuring etcd certs/keys | etchosts | Configuring /etc/hosts entries for hosts | external-cloud-controller | Configure cloud controllers | external-openstack | Cloud controller : openstack | external-provisioner | Configure external provisioners | external-vsphere | Cloud controller : vsphere | facts | Gathering facts and misc check results | files | Remove files when resetting | flannel | Network plugin flannel | gce | Cloud-provider GCP | gcp-pd-csi-driver | Configuring csi driver: gcp-pd | gvisor | Configuring gvisor runtime | helm | Installing and configuring Helm | ingress-controller | Configure ingress controllers | ingress_alb | AWS ALB Ingress Controller | init | Windows kubernetes init nodes | iptables | Flush and clear iptable when resetting | k8s-pre-upgrade | Upgrading K8s cluster | k8s-secrets | Configuring K8s certs/keys | k8s-gen-tokens | Configuring K8s tokens | kata-containers | Configuring kata-containers runtime | krew | Install and manage krew | kubeadm | Roles linked to kubeadm tasks | kube-apiserver | Configuring static pod kube-apiserver | kube-controller-manager | Configuring static pod kube-controller-manager | kubectl | Installing kubectl and bash completion | kubelet | Configuring kubelet service | kube-ovn | Network plugin kube-ovn | kube-router | Network plugin kube-router | kube-proxy | Configuring static pod kube-proxy | localhost | Special steps for the localhost (ansible runner) | local-path-provisioner | Configure External provisioner: local-path | local-volume-provisioner | Configure External provisioner: local-volume | macvlan | Network plugin macvlan | master | Configuring K8s master node role | metallb | Installing and configuring metallb | metrics_server | Configuring metrics_server | netchecker | Installing netchecker K8s app | network | Configuring networking plugins for K8s | mounts | Umount kubelet dirs when reseting | multus | Network plugin multus | nginx | Configuring LB for kube-apiserver instances | node | Configuring K8s minion (compute) node role | nodelocaldns | Configuring nodelocaldns daemonset | node-label | Tasks linked to labeling of nodes | node-webhook | Tasks linked to webhook (grating access to resources) | nvidia_gpu | Enable nvidia accelerator for runtimes | oci | Cloud provider: oci | ovn4nfv | Network plugin ovn4nfv | persistent_volumes | Configure csi volumes | persistent_volumes_aws_ebs_csi | Configuring csi driver: aws-ebs | persistent_volumes_cinder_csi | Configuring csi driver: cinder | persistent_volumes_gcp_pd_csi | Configuring csi driver: gcp-pd | persistent_volumes_openstack | Configuring csi driver: openstack | policy-controller | Configuring Calico policy controller | post-remove | Tasks running post-remove operation | post-upgrade | Tasks running post-upgrade operation | pre-remove | Tasks running pre-remove operation | pre-upgrade | Tasks running pre-upgrade operation | preinstall | Preliminary configuration steps | registry | Configuring local docker registry | reset | Tasks running doing the node reset | resolvconf | Configuring /etc/resolv.conf for hosts/apps | rbd-provisioner | Configure External provisioner: rdb | services | Remove services (etcd, kubelet etc...) when resetting | snapshot | Enabling csi snapshot | snapshot-controller | Configuring csi snapshot controller | upgrade | Upgrading, f.e. container images/binaries | upload | Distributing images/binaries across hosts | vsphere-csi-driver | Configuring csi driver: vsphere | weave | Network plugin Weave | win_nodes | Running windows specific tasks Note: Use the ``bash scripts/gen_tags.sh`` command to generate a list of all tags found in the codebase. New tags will be listed with the empty "Used for" field. ## Example commands Example command to filter and apply only DNS configuration tasks and skip everything else related to host OS configuration and downloading images of containers: ```ShellSession ansible-playbook -i inventory/sample/hosts.ini cluster.yml --tags preinstall,facts --skip-tags=download,bootstrap-os ``` And this play only removes the K8s cluster DNS resolver IP from hosts' /etc/resolv.conf files: ```ShellSession ansible-playbook -i inventory/sample/hosts.ini -e dns_mode='none' cluster.yml --tags resolvconf ``` And this prepares all container images locally (at the ansible runner node) without installing or upgrading related stuff or trying to upload container to K8s cluster nodes: ```ShellSession ansible-playbook -i inventory/sample/hosts.ini cluster.yml \ -e download_run_once=true -e download_localhost=true \ --tags download --skip-tags upload,upgrade ``` Note: use `--tags` and `--skip-tags` wise and only if you're 100% sure what you're doing. ## Bastion host If you prefer to not make your nodes publicly accessible (nodes with private IPs only), you can use a so called *bastion* host to connect to your nodes. To specify and use a bastion, simply add a line to your inventory, where you have to replace x.x.x.x with the public IP of the bastion host. ```ShellSession [bastion] bastion ansible_host=x.x.x.x ``` For more information about Ansible and bastion hosts, read [Running Ansible Through an SSH Bastion Host](https://blog.scottlowe.org/2015/12/24/running-ansible-through-ssh-bastion-host/) ## Mitogen You can use [mitogen](/docs/mitogen.md) to speed up kubespray. ## Beyond ansible 2.9 Ansible project has decided, in order to ease their maintenance burden, to split between two projects which are now joined under the Ansible umbrella. Ansible-base (2.10.x branch) will contain just the ansible language implementation while ansible modules that were previously bundled into a single repository will be part of the ansible 3.x package. Pleasee see [this blog post](https://blog.while-true-do.io/ansible-release-3-0-0/) that explains in detail the need and the evolution plan. **Note:** this change means that ansible virtual envs cannot be upgraded with `pip install -U`. You first need to uninstall your old ansible (pre 2.10) version and install the new one. ```ShellSession pip uninstall ansible cd kubespray/ pip install -U . ``` **Note:** some changes needed to support ansible 2.10+ are not backwards compatible with 2.9 Kubespray needs to evolve and keep pace with upstream ansible and will be forced to eventually drop 2.9 support. Kubespray CIs use only the ansible version specified in the `requirements.txt` and while the `ansible_version.yml` may allow older versions to be used, these are not exercised in the CI and compatibility is not guaranteed.