kubespray/docs/getting-started.md

Getting started
===============

Building your own inventory
---------------------------

Ansible inventory can be stored in 3 formats: YAML, JSON, or INI-like. There is
an example inventory located
[here](https://github.com/kubernetes-sigs/kubespray/blob/master/inventory/sample/inventory.ini).

You can use an
[inventory generator](https://github.com/kubernetes-sigs/kubespray/blob/master/contrib/inventory_builder/inventory.py)
to create or modify an Ansible inventory. Currently, it is limited in
functionality and is only used for configuring a basic Kubespray cluster inventory, but it does
support creating inventory file for large clusters as well. It now supports
separated ETCD and Kubernetes master roles from node role if the size exceeds a
certain threshold. Run `python3 contrib/inventory_builder/inventory.py help` help for more information.

Example inventory generator usage:

    cp -r inventory/sample inventory/mycluster
    declare -a IPS=(10.10.1.3 10.10.1.4 10.10.1.5)
    CONFIG_FILE=inventory/mycluster/hosts.yml python3 contrib/inventory_builder/inventory.py ${IPS[@]}

Then use `inventory/mycluster/hosts.yml` as inventory file.

Starting custom deployment
--------------------------

Once you have an inventory, you may want to customize deployment data vars
and start the deployment:

**IMPORTANT**: Edit my\_inventory/groups\_vars/\*.yaml to override data vars:

    ansible-playbook -i inventory/mycluster/hosts.yml cluster.yml -b -v \
      --private-key=~/.ssh/private_key

See more details in the [ansible guide](ansible.md).

Adding nodes
------------

You may want to add worker, master or etcd nodes to your existing cluster. This can be done by re-running the `cluster.yml` playbook, or you can target the bare minimum needed to get kubelet installed on the worker and talking to your masters. This is especially helpful when doing something like autoscaling your clusters.

-   Add the new worker node to your inventory in the appropriate group (or utilize a [dynamic inventory](https://docs.ansible.com/ansible/intro_dynamic_inventory.html)).
-   Run the ansible-playbook command, substituting `cluster.yml` for `scale.yml`:

        ansible-playbook -i inventory/mycluster/hosts.yml scale.yml -b -v \
          --private-key=~/.ssh/private_key

Remove nodes
------------

You may want to remove **master**, **worker**, or **etcd** nodes from your
existing cluster. This can be done by re-running the `remove-node.yml`
playbook. First, all specified nodes will be drained, then stop some
kubernetes services and delete some certificates,
and finally execute the kubectl command to delete these nodes.
This can be combined with the add node function. This is generally helpful
when doing something like autoscaling your clusters. Of course, if a node
is not working, you can remove the node and install it again.

Use `--extra-vars "node=<nodename>,<nodename2>"` to select the node(s) you want to delete.
```
ansible-playbook -i inventory/mycluster/hosts.yml remove-node.yml -b -v \
  --private-key=~/.ssh/private_key \
  --extra-vars "node=nodename,nodename2"
```

If a node is completely unreachable by ssh, add `--extra-vars reset_nodes=no`
to skip the node reset step. If one node is unavailable, but others you wish
to remove are able to connect via SSH, you could set reset_nodes=no as a host
var in inventory.

Connecting to Kubernetes
------------------------

By default, Kubespray configures kube-master hosts with insecure access to
kube-apiserver via port 8080. A kubeconfig file is not necessary in this case,
because kubectl will use <http://localhost:8080> to connect. The kubeconfig files
generated will point to localhost (on kube-masters) and kube-node hosts will
connect either to a localhost nginx proxy or to a loadbalancer if configured.
More details on this process are in the [HA guide](ha-mode.md).

Kubespray permits connecting to the cluster remotely on any IP of any
kube-master host on port 6443 by default. However, this requires
authentication. One could generate a kubeconfig based on one installed
kube-master hosts (needs improvement) or connect with a username and password.
By default, a user with admin rights is created, named `kube`.
The password can be viewed after deployment by looking at the file
`{{ credentials_dir }}/kube_user.creds` (`credentials_dir` is set to `{{ inventory_dir }}/credentials` by default). This contains a randomly generated
password. If you wish to set your own password, just precreate/modify this
file yourself.

For more information on kubeconfig and accessing a Kubernetes cluster, refer to
the Kubernetes [documentation](https://kubernetes.io/docs/tasks/access-application-cluster/configure-access-multiple-clusters/).

Accessing Kubernetes Dashboard
------------------------------

As of kubernetes-dashboard v1.7.x:

-   New login options that use apiserver auth proxying of token/basic/kubeconfig by default
-   Requires RBAC in authorization\_modes
-   Only serves over https
-   No longer available at <https://first_master:6443/ui> until apiserver is updated with the https proxy URL

If the variable `dashboard_enabled` is set (default is true), then you can access the Kubernetes Dashboard at the following URL, You will be prompted for credentials:
<https://first_master:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login>

Or you can run 'kubectl proxy' from your local machine to access dashboard in your browser from:
<http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login>

It is recommended to access dashboard from behind a gateway (like Ingress Controller) that enforces an authentication token. Details and other access options here: <https://github.com/kubernetes/dashboard/wiki/Accessing-Dashboard---1.7.X-and-above>

Accessing Kubernetes API
------------------------

The main client of Kubernetes is `kubectl`. It is installed on each kube-master
host and can optionally be configured on your ansible host by setting
`kubectl_localhost: true` and `kubeconfig_localhost: true` in the configuration:

-   If `kubectl_localhost` enabled, `kubectl` will download onto `/usr/local/bin/` and setup with bash completion. A helper script `inventory/mycluster/artifacts/kubectl.sh` also created for setup with below `admin.conf`.
-   If `kubeconfig_localhost` enabled `admin.conf` will appear in the `inventory/mycluster/artifacts/` directory after deployment.

You can see a list of nodes by running the following commands:

    cd inventory/mycluster/artifacts
    ./kubectl.sh get nodes

If desired, copy admin.conf to ~/.kube/config.