130 lines
7.8 KiB
Markdown
130 lines
7.8 KiB
Markdown
Introduction
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============
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Assuming you have Vagrant 2.0+ installed with virtualbox, libvirt/qemu or vmware, but is untested) you should be able to launch a 3 node Kubernetes cluster by simply running `vagrant up`. This will spin up 3 VMs and install kubernetes on them. Once they are completed you can connect to any of them by running `vagrant ssh k8s-[1..3]`.
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To give an estimate of the expected duration of a provisioning run: On a dual core i5-6300u laptop with an SSD, provisioning takes around 13 to 15 minutes, once the container images and other files are cached. Note that libvirt/qemu is recommended over virtualbox as it is quite a bit faster, especially during boot-up time.
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For proper performance a minimum of 12GB RAM is recommended. It is possible to run a 3 node cluster on a laptop with 8GB of RAM using the default Vagrantfile, provided you have 8GB zram swap configured and not much more than a browser and a mail client running. If you decide to run on such a machine, then also make sure that any tmpfs devices, that are mounted, are mostly empty and disable any swapfiles mounted on HDD/SSD or you will be in for some serious swap-madness. Things can get a bit sluggish during provisioning, but when that's done, the system will actually be able to perform quite well.
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Customize Vagrant
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=================
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You can override the default settings in the `Vagrantfile` either by directly modifying the `Vagrantfile` or through an override file. In the same directory as the `Vagrantfile`, create a folder called `vagrant` and create `config.rb` file in it. An example of how to configure this file is given below.
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Use alternative OS for Vagrant
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==============================
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By default, Vagrant uses Ubuntu 18.04 box to provision a local cluster. You may use an alternative supported operating system for your local cluster.
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Customize `$os` variable in `Vagrantfile` or as override, e.g.,:
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echo '$os = "coreos-stable"' >> vagrant/config.rb
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The supported operating systems for vagrant are defined in the `SUPPORTED_OS` constant in the `Vagrantfile`.
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File and image caching
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======================
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Kubespray can take quite a while to start on a laptop. To improve provisioning speed, the variable 'download_run_once' is set. This will make kubespray download all files and containers just once and then redistributes them to the other nodes and as a bonus, also cache all downloads locally and re-use them on the next provisioning run. For more information on download settings see [download documentation](docs/downloads.md).
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Example use of Vagrant
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======================
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The following is an example of setting up and running kubespray using `vagrant`. For repeated runs, you could save the script to a file in the root of the kubespray and run it by executing 'source <name_of_the_file>.
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```
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# use virtualenv to install all python requirements
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VENVDIR=venv
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virtualenv --python=/usr/bin/python3.7 $VENVDIR
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source $VENVDIR/bin/activate
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pip install -r requirements.txt
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# prepare an inventory to test with
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INV=inventory/my_lab
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rm -rf ${INV}.bak &> /dev/null
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mv ${INV} ${INV}.bak &> /dev/null
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cp -a inventory/sample ${INV}
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rm -f ${INV}/hosts.ini
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# customize the vagrant environment
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mkdir vagrant
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cat << EOF > vagrant/config.rb
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\$instance_name_prefix = "kub"
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\$vm_cpus = 1
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\$num_instances = 3
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\$os = "centos-bento"
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\$subnet = "10.0.20"
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\$network_plugin = "flannel"
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\$inventory = "$INV"
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\$shared_folders = { 'temp/docker_rpms' => "/var/cache/yum/x86_64/7/docker-ce/packages" }
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EOF
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# make the rpm cache
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mkdir -p temp/docker_rpms
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vagrant up
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# make a copy of the downloaded docker rpm, to speed up the next provisioning run
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scp kub-1:/var/cache/yum/x86_64/7/docker-ce/packages/* temp/docker_rpms/
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# copy kubectl access configuration in place
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mkdir $HOME/.kube/ &> /dev/null
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ln -s $INV/artifacts/admin.conf $HOME/.kube/config
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# make the kubectl binary available
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sudo ln -s $INV/artifacts/kubectl /usr/local/bin/kubectl
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#or
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export PATH=$PATH:$INV/artifacts
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```
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If a vagrant run failed and you've made some changes to fix the issue causing the fail, here is how you would re-run ansible:
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```
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ansible-playbook -vvv -i .vagrant/provisioners/ansible/inventory/vagrant_ansible_inventory cluster.yml
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```
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If all went well, you check if it's all working as expected:
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```
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kubectl get nodes
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```
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The output should look like this:
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```
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$ kubectl get nodes
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NAME STATUS ROLES AGE VERSION
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kub-1 Ready master 32m v1.14.1
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kub-2 Ready master 31m v1.14.1
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kub-3 Ready <none> 31m v1.14.1
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```
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Another nice test is the following:
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```
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kubectl get po --all-namespaces -o wide
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```
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Which should yield something like the following:
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```
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NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
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kube-system coredns-97c4b444f-9wm86 1/1 Running 0 31m 10.233.66.2 kub-3 <none> <none>
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kube-system coredns-97c4b444f-g7hqx 0/1 Pending 0 30m <none> <none> <none> <none>
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kube-system dns-autoscaler-5fc5fdbf6-5c48k 1/1 Running 0 31m 10.233.66.3 kub-3 <none> <none>
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kube-system kube-apiserver-kub-1 1/1 Running 0 32m 10.0.20.101 kub-1 <none> <none>
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kube-system kube-apiserver-kub-2 1/1 Running 0 32m 10.0.20.102 kub-2 <none> <none>
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kube-system kube-controller-manager-kub-1 1/1 Running 0 32m 10.0.20.101 kub-1 <none> <none>
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kube-system kube-controller-manager-kub-2 1/1 Running 0 32m 10.0.20.102 kub-2 <none> <none>
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kube-system kube-flannel-8tgcn 2/2 Running 0 31m 10.0.20.103 kub-3 <none> <none>
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kube-system kube-flannel-b2hgt 2/2 Running 0 31m 10.0.20.101 kub-1 <none> <none>
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kube-system kube-flannel-zx4bc 2/2 Running 0 31m 10.0.20.102 kub-2 <none> <none>
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kube-system kube-proxy-4bjdn 1/1 Running 0 31m 10.0.20.102 kub-2 <none> <none>
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kube-system kube-proxy-l5tt5 1/1 Running 0 31m 10.0.20.103 kub-3 <none> <none>
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kube-system kube-proxy-x59q8 1/1 Running 0 31m 10.0.20.101 kub-1 <none> <none>
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kube-system kube-scheduler-kub-1 1/1 Running 0 32m 10.0.20.101 kub-1 <none> <none>
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kube-system kube-scheduler-kub-2 1/1 Running 0 32m 10.0.20.102 kub-2 <none> <none>
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kube-system kubernetes-dashboard-6c7466966c-jqz42 1/1 Running 0 31m 10.233.66.4 kub-3 <none> <none>
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kube-system nginx-proxy-kub-3 1/1 Running 0 32m 10.0.20.103 kub-3 <none> <none>
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kube-system nodelocaldns-2x7vh 1/1 Running 0 31m 10.0.20.102 kub-2 <none> <none>
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kube-system nodelocaldns-fpvnz 1/1 Running 0 31m 10.0.20.103 kub-3 <none> <none>
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kube-system nodelocaldns-h2f42 1/1 Running 0 31m 10.0.20.101 kub-1 <none> <none>
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```
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Create clusteradmin rbac and get the login token for the dashboard:
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```
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kubectl create -f contrib/misc/clusteradmin-rbac.yml
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kubectl -n kube-system describe secret kubernetes-dashboard-token | grep 'token:' | grep -o '[^ ]\+$'
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```
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Copy it to the clipboard and now log in to the [dashboard](https://10.0.20.101:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login).
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