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Setup local and production hybrid clusters, using Ansible and Vagrant

Project description

General

k8s-setup provides instant access to a configured Kubernetes cluster, based on kubeadm. It allows to provision the cluster to a local machine as well as to production. It is made with the help from Ansible, and Vagrant for local virtual setup in VirtualBox.

Note: Currently only Linux is supported for local VM deployment, but it is designed in a way, that Windows support is possible. It just needs to be implemented.

How to use

Install by pip

Every released version will have a wheel package pushed to PyPI. You can install it by pip install k8s-setup

Install by git

  1. Clone the repository
  2. Install python (>=2.7) and pip
  3. Install the package editable by pip install GitPython && pip install --editable .
  4. Vagrant (tested against Vagrant 2.2.4)
  5. VirtualBox (tested against VirtualBox 6.0.12)

The steps 4. and 5. are only required, if you want to setup a local virtual cluster.

Provide the configuration

Local Deployment

For local vm deployments, the default 'vagrant.yml' file should work. You don't need to provide a custom configuration, if you just want a vm cluster with a single control plane and worker node.

To access the cluster from your machine, you should have an host record for the apiserver. The IP is configured by the k8s_apiserver_vip configuration setting. The hostname is constructed by the k8s_apiserver_hostname and k8s_cluster_dnsname settings.

To generate the correct /etc/hosts file, you can run k8s-setup generate hostsfile --merge. The --merge flag instructs the generator to merge the current /etc/hosts file with the generated records.

NOTE: Because write-access to /etc/hosts needs root permissions, you can't just simply redirect the output to /etc/hosts. I used a temporary file, with a move operation: k8s-setup generate hostsfile --merge > /tmp/hosts && sudo mv /tmp/hosts /etc/hosts First you should run the generator before running the provisioner, because it needs a 'apiserver' host. After provisioning is done, run it again, so that the ingress hosts are included.

Production Deployment

For production deployments, you need to:

  1. Create an Ansible inventory file, with the machines in it. You need to assign the host to these groups:

    • lnxclp: All Linux control plane nodes
    • lnxclp_setup: One of the Linux control plane nodes, which will be the first control plane instance
    • lnxwrk: All Linux worker nodes
    • winwrk: All Windows worker nodes
  2. Create a .yml file, representing variables of your environment. You can check the provided files in '/conf'. The 'default.yml' contains the system default settings. You can override them in your custom configuration file.

  3. Register a custom configuration by executing k8s-setup config set --file <path>. The path can be absolute, or relative to the repository root. By default the ./conf/vagrant.yml is selected.

This Information is stored in ~/k8s-setup/current-config. It is persistent, so normally you only have to execute it once. 4. You may verify if everything is ok by running k8s-setup info

Provide the configuration in an own repository

k8s-setup doesn't care, where the config file is coming from. Just clone the repository containing your configuration file, and register it by k8s-setup config <path>.

Running the provisioners

By executing k8s-setup provision you start the provisioning process.

Because provisioning is idempotent, you can always use provision 'all'. The ability to select a scope explicitly is just a time-saver, when you know what has hanged. This is basically to cut wait-time when developing and testing k8s-setup. If you don't know what has changed exacly, always provision the 'all' scope.

The following steps will be performed in the 'vagrant' mode:

  1. The configuration is validated.
  2. Vagrant only: The relevant configuration settings are reflected in environment variables.
  3. Vagrant only: The ./lib/vagrant/Vagrantfile is used to start the VMs, depending on the reflected environmet variables.
  4. Vagrant only: The Vagrantfile declares the following provisioners:
    • Host: Updates the /etc/hosts files on each machine, because we have no DNS server in the network.
    • Ansible: Runs the ./lib/ansible/vagrant.yml playbook. This playbook only performs connectivity tests. The provisioning playbooks are launched later. The Ansible provisioner also generates an inventory file, which is used in the next step.
  5. Depending on the scope, the following playbooks are executed:
    • all (default): Runs hosts, cluster and incluster playbooks.
    • hosts: Provisions the machines so that everything is installed and OS level configuration is applied, but no kubeadm operation to deploy the cluster was performed.
    • cluster: Provisions by kubeadm operations like kubeadm init or kubeadm join to initialize the cluster, or add new nodes.
    • incluster: Provisions all kubernetes objects in an existing cluster.

Get Information

By using the k8s-setup info command, you get some metadata of the k8s-setup state and configuration.

$ k8s-setup info
config-files:
- conf/defaults.yml
- localpath/k8s-setup/conf/vagrant.yml
configuration:
  ansible_inventory_filepath: lib/vagrant/.vagrant/provisioners/ansible/inventory/vagrant_ansible_inventory
  cluster-dns-name: k8stest.local
  k8s-version: 1.16.3
  lnxclp-nodes: 1
  lnxwrk-nodes: 1
  mode: vagrant
  winwrk-nodes: 0
version: v0.1-alpha-base-7-gd978c740a5c526+dirty

When running the 'cluster' provisioning scope, a ConfigMap named 'k8s-setup-info' is created in the 'default' namespace. It contains this information in the 'setup-info' field. There is an additional field named 'sys-info', containing information like the date, the user of the name of the provisioning host.

Please note that the provisioning logic don't read this data. It only serves informational purposes.

Enable Shell Completion

With the help of the wonderfull click library k8s-setup has buildin completion for bash and zsh.

You need to activate this, like:

# bash (you may put this in .bashrc)
eval "$(_K8S_SETUP_COMPLETE=source k8s-setup)"

# zsh (you may put this in .zshrc)
eval "$(_K8S_SETUP_COMPLETE=source_zsh k8s-setup)"

Output debug Messages

You can enable Debug level logging, by setting the K8S_SETUP_DEBUG environment variable to '1'.

You can also use the --debug command line option.

Vagrant Development Environment

Networking

k8s-setup uses a default IP plan to setup the cluster network: There is a configurable /24 network which is used for the Vagrant boxes.

# conf/defaults.yml
global_vagrant_hosts_network: 10.0.0.*

You only need to change this settings, if you have conflicting IP addresses in your LAN.

The following addresses are used:

  • 10.0.0.1: Reserver (Gateway)
  • 10.0.0.2: Virtual IP (keepalived) for apiserver
  • 10.0.0.10-19: Control plane nodes
  • 10.0.0.20-29: Linux worker nodes
  • 10.0.0.30-39: Windows worker nodes
  • 10.0.0.40-49: None-cluster nodes (like test-clients or AD server)

After the hosts are provisioned, you get a route by virtualbox, like:

$ ip route | grep 10.0.0.0
10.0.0.0/24 dev vboxnet3 proto kernel scope link src 10.0.0.1 

So you can just access the network from you host. You may add an entry in your /etc/hosts file, like 10.0.0.2 apiserver.k8stest.local

https://setuptools.readthedocs.io/en/latest/setuptools.html#automatic-resource-extraction

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