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Ansible variables===============
Inventory-------------The inventory is composed of 3 groups:
* **kube-node** : list of kubernetes nodes where the pods will run.* **kube-master** : list of servers where kubernetes master 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 puttingthe _etcd_ group into the _k8s-cluster_, unless you are certainto do that and you have it fully contained in the latter:
```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 master and node, the server must be definedon both groups _kube-master_ and _kube-node_. If you want a standalone andunschedulable master, the server must be defined only in the _kube-master_ andnot _kube-node_.
There are also two special groups:
* **calico-rr** : explained for [advanced Calico networking cases](calico.md)* **bastion** : configure a bastion host if your nodes are not directly reachable
Below is a complete inventory example:
```## Configure 'ip' variable to bind kubernetes services on a
## different ip than the default iface
node1 ansible_ssh_host=95.54.0.12 ip=10.3.0.1node2 ansible_ssh_host=95.54.0.13 ip=10.3.0.2node3 ansible_ssh_host=95.54.0.14 ip=10.3.0.3node4 ansible_ssh_host=95.54.0.15 ip=10.3.0.4node5 ansible_ssh_host=95.54.0.16 ip=10.3.0.5node6 ansible_ssh_host=95.54.0.17 ip=10.3.0.6
[kube-master]node1node2
[etcd]node1node2node3
[kube-node]node2node3node4node5node6
[k8s-cluster:children]kube-nodekube-master```
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, rkt, kubernetes preinstall and master roles.According to the [ansible docs](http://docs.ansible.com/ansible/playbooks_variables.html#variable-precedence-where-should-i-put-a-variable),those cannot be overriden from the group vars. In order to override, one should usethe `-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 tobe overriden for roles):
Layer | Comment------|--------**role defaults** | provides best UX to override things for Kubespray deploymentsinventory vars | Unused**inventory group_vars** | Expects users to use ``all.yml``,``k8s-cluster.yml`` etc. to override thingsinventory host_vars | Unusedplaybook group_vars | Unusedplaybook host_vars | Unused**host facts** | Kubespray overrides for internal roles' logic, like state flagsplay vars | Unusedplay vars_prompt | Unusedplay vars_files | Unusedregistered vars | Unusedset_facts | Kubespray overrides those, for some places**role and include vars** | Provides bad UX to override things! Use extra vars to enforceblock vars (only for tasks in block) | Kubespray overrides for internal roles' logictask 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|--------------------------|---------| apps | K8s apps definitions| azure | Cloud-provider Azure| bastion | Setup ssh config for bastion| bootstrap-os | Anything related to host OS configuration| calico | Network plugin Calico| canal | Network plugin Canal| cloud-provider | Cloud-provider related tasks| dnsmasq | Configuring DNS stack for hosts and K8s apps| docker | Configuring docker for hosts| download | Fetching container images to a delegate host| etcd | Configuring etcd cluster| etcd-pre-upgrade | Upgrading etcd cluster| etcd-secrets | Configuring etcd certs/keys| etchosts | Configuring /etc/hosts entries for hosts| facts | Gathering facts and misc check results| flannel | Network plugin flannel| gce | Cloud-provider GCP| hyperkube | Manipulations with K8s hyperkube image| k8s-pre-upgrade | Upgrading K8s cluster| k8s-secrets | Configuring K8s certs/keys| 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-proxy | Configuring static pod kube-proxy| kube-scheduler | Configuring static pod kube-scheduler| localhost | Special steps for the localhost (ansible runner)| master | Configuring K8s master node role| netchecker | Installing netchecker K8s app| network | Configuring networking plugins for K8s| nginx | Configuring LB for kube-apiserver instances| node | Configuring K8s minion (compute) node role| openstack | Cloud-provider OpenStack| preinstall | Preliminary configuration steps| resolvconf | Configuring /etc/resolv.conf for hosts/apps| upgrade | Upgrading, f.e. container images/binaries| upload | Distributing images/binaries across hosts| weave | Network plugin Weave
Note: Use the ``bash scripts/gen_tags.sh`` command to generate a list of alltags 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 skipeverything else related to host OS configuration and downloading images of containers:
```ansible-playbook -i inventory/sample/hosts.ini cluster.yml --tags preinstall,dnsmasq,facts --skip-tags=download,bootstrap-os```And this play only removes the K8s cluster DNS resolver IP from hosts' /etc/resolv.conf files:```ansible-playbook -i inventory/sample/hosts.ini -e dnsmasq_dns_server='' cluster.yml --tags resolvconf```And this prepares all container images localy (at the ansible runner node) without installingor upgrading related stuff or trying to upload container to K8s cluster nodes:```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 thebastion host.
```bastion ansible_ssh_host=x.x.x.x```
For more information about Ansible and bastion hosts, read[Running Ansible Through an SSH Bastion Host](http://blog.scottlowe.org/2015/12/24/running-ansible-through-ssh-bastion-host/)
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