c12s-kubespray/docs/ansible.md

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Ansible variables
===============
Inventory
-------------
The inventory is composed of 3 groups:
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* **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.
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Note: if you want the server to act both as master and node the server must be defined on both groups _kube-master_ and _kube-node_
* **etcd**: list of server to compose the etcd server. you should have at least 3 servers for failover purposes.
Below is a complete inventory example:
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```
## Configure 'ip' variable to bind kubernetes services on a
## different ip than the default iface
node1 ansible_ssh_host=95.54.0.12 # ip=10.3.0.1
node2 ansible_ssh_host=95.54.0.13 # ip=10.3.0.2
node3 ansible_ssh_host=95.54.0.14 # ip=10.3.0.3
node4 ansible_ssh_host=95.54.0.15 # ip=10.3.0.4
node5 ansible_ssh_host=95.54.0.16 # ip=10.3.0.5
node6 ansible_ssh_host=95.54.0.17 # ip=10.3.0.6
[kube-master]
node1
node2
[etcd]
node1
node2
node3
[kube-node]
node2
node3
node4
node5
node6
[k8s-cluster:children]
kube-node
kube-master
etcd
```
Group vars
--------------
The main variables to change are located in the directory ```inventory/group_vars/all.yml```.
Ansible tags
------------
The following tags are defined in playbooks:
| Tag name | Used for
|--------------------------|---------
| apps | K8s apps definitions
| azure | Cloud-provider Azure
| 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
| kpm | Installing K8s apps definitions with KPM
| kube-apiserver | Configuring self-hosted kube-apiserver
| kube-controller-manager | Configuring self-hosted kube-controller-manager
| kubectl | Installing kubectl and bash completion
| kubelet | Configuring kubelet service
| kube-proxy | Configuring self-hosted kube-proxy
| kube-scheduler | Configuring self-hosted 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 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:
```
ansible-playbook -i inventory/inventory.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/inventory.ini -e dns_server='' cluster.yml --tags resolvconf
```
And this prepares all container images localy (at the ansible runner node) without installing
or upgrading related stuff or trying to upload container to K8s cluster nodes:
```
ansible-playbook -i inventory/inventory.ini cluster.yaml \
-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.