Quickstart Guide¶
To quickly set up a testing cluster using MetalK8s, you need 3 machines running CentOS 7.4 to which you have SSH access (these can be VMs). Each machine acting as a Kubernetes node (all of them, in this example) also need to have at least one disk available to provision storage volumes.
Todo
Give some sizing examples
Defining an Inventory¶
To tell the Ansible-based deployment system on which machines MetalK8s should be installed, a so-called inventory needs to be provided. This inventory contains a file listing all the hosts comprising the cluster, as well as some configuration.
First, create a directory, e.g. inventory/quickstart-cluster, in which
the inventory will be stored. For our setup, we need to create two files. One
listing all the hosts, aptly called hosts:
node-01 ansible_host=10.0.0.1 ansible_user=centos
node-02 ansible_host=10.0.0.2 ansible_user=centos
node-03 ansible_host=10.0.0.3 ansible_user=centos
[kube-master]
node-01
node-02
node-03
[etcd]
node-01
node-02
node-03
[kube-node]
node-01
node-02
node-03
[k8s-cluster:children]
kube-node
kube-master
Make sure to change IP-addresses, usernames etc. according to your infrastructure.
In a second file, called kube-node.yml in a group_vars
subdirectory of our inventory, we declare how to setup storage (in the
default configuration) on hosts in the kube-node group, i.e. hosts on which
Pods will be scheduled:
metal_k8s_lvm:
vgs:
kubevg:
drives: ['/dev/vdb']
In the above, we assume every kube-node host has a disk available as
/dev/vdb which can be used to set up Kubernetes PersistentVolumes. For
more information about storage, see Storage Architecture.
Entering the MetalK8s Shell¶
To easily install a supported version of Ansible and its dependencies, as well as some Kubernetes tools (kubectl and helm), we provide a make target which installs these in a local environment. To enter this environment, run make shell (this takes a couple of seconds on first run):
$ make shell
Creating virtualenv...
Installing Python dependencies...
Downloading kubectl...
Downloading Helm...
Launching MetalK8s shell environment. Run 'exit' to quit.
(metal-k8s) $
Now we’re all set to deploy a cluster:
(metal-k8s) $ ansible-playbook -i inventory/quickstart-cluster -b playbooks/deploy.yml
Grab a coffee and wait for deployment to end.
Inspecting the cluster¶
Once deployment finished, a file containing credentials to access the cluster is
created: inventory/quickstart-cluster/artifacts/admin.conf. We can
export this location in the shell such that the kubectl and
helm tools know how to contact the cluster kube-master nodes, and
authenticate properly:
(metal-k8s) $ export KUBECONFIG=`pwd`/inventory/quickstart-cluster/artifacts/admin.conf
Now, assuming port 6443 on the first kube-master node is reachable from your system, we can e.g. list the nodes:
(metal-k8s) $ kubectl get nodes
NAME STATUS ROLES AGE VERSION
node-01 Ready master,node 1m v1.9.5+coreos.0
node-02 Ready master,node 1m v1.9.5+coreos.0
node-03 Ready master,node 1m v1.9.5+coreos.0
or list all pods:
(metal-k8s) $ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-ingress nginx-ingress-controller-9d8jh 1/1 Running 0 1m
kube-ingress nginx-ingress-controller-d7vvg 1/1 Running 0 1m
kube-ingress nginx-ingress-controller-m8jpq 1/1 Running 0 1m
kube-ingress nginx-ingress-default-backend-6664bc64c9-xsws5 1/1 Running 0 1m
kube-ops alertmanager-kube-prometheus-0 2/2 Running 0 2m
kube-ops alertmanager-kube-prometheus-1 2/2 Running 0 2m
kube-ops es-client-7cf569f5d8-2z974 1/1 Running 0 2m
kube-ops es-client-7cf569f5d8-qq4h2 1/1 Running 0 2m
kube-ops es-data-cd5446fff-pkmhn 1/1 Running 0 2m
kube-ops es-data-cd5446fff-zzd2h 1/1 Running 0 2m
kube-ops es-exporter-elasticsearch-exporter-7df5bcf58b-k9fdd 1/1 Running 3 1m
...
Similarly, we can list all deployed Helm applications:
(metal-k8s) $ helm list
NAME REVISION UPDATED STATUS CHART NAMESPACE
es-exporter 3 Wed Apr 25 23:10:13 2018 DEPLOYED elasticsearch-exporter-0.1.2 kube-ops
fluentd 3 Wed Apr 25 23:09:59 2018 DEPLOYED fluentd-elasticsearch-0.1.4 kube-ops
heapster 3 Wed Apr 25 23:09:37 2018 DEPLOYED heapster-0.2.7 kube-system
kibana 3 Wed Apr 25 23:10:06 2018 DEPLOYED kibana-0.2.2 kube-ops
kube-prometheus 3 Wed Apr 25 23:09:22 2018 DEPLOYED kube-prometheus-0.0.33 kube-ops
nginx-ingress 3 Wed Apr 25 23:09:09 2018 DEPLOYED nginx-ingress-0.11.1 kube-ingress
prometheus-operator 3 Wed Apr 25 23:09:14 2018 DEPLOYED prometheus-operator-0.0.15 kube-ops
Access to dashboard, Grafana and Kibana¶
Once the cluster is running, you can access the Kubernetes dashboard, Grafana metrics and Kibana logs from your browser.
To access these services, first create a secure tunnel into your
cluster by running kubectl proxy. Then, while the tunnel is up and running,
access the dashboard at
http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/,
Grafana at
http://localhost:8001/api/v1/namespaces/kube-ops/services/kube-prometheus-grafana:http/proxy/
and Kibana at
http://localhost:8001/api/v1/namespaces/kube-ops/services/http:kibana:/proxy/.
When accessing Kibana for the first time, set up an index pattern for the
logstash-* index, using the @timestamp field as Time Filter field
name.
See Cluster Services for more information about these services and their configuration.