7.8 KiB
*** PLEASE NOTE: This document applies to the HEAD of the source tree only. If you are using a released version of Kubernetes, you almost certainly want the docs that go with that version.
Documentation for specific releases can be found at releases.k8s.io.
Getting started with Kubernetes on Mesos
Table of Contents
About Kubernetes on Mesos
Mesos allows dynamic sharing of cluster resources between Kubernetes and other first-class Mesos frameworks such as Hadoop, Spark, and Chronos. Mesos also ensures applications from different frameworks running on your cluster are isolated and that resources are allocated fairly among them.
Mesos clusters can be deployed on nearly every IaaS cloud provider infrastructure or in your own physical datacenter. Kubernetes on Mesos runs on-top of that and therefore allows you to easily move Kubernetes workloads from one of these environments to the other.
This tutorial will walk you through setting up Kubernetes on a Mesos cluster. It provides a step by step walk through of adding Kubernetes to a Mesos cluster and starting your first pod with an nginx webserver.
NOTE: There are known issues with the current implementation and support for centralized logging and monitoring is not yet available. Please file an issue against the kubernetes-mesos project if you have problems completing the steps below.
Prerequisites
- Understanding of Apache Mesos
- A running Mesos cluster on Google Compute Engine
- A VPN connection to the cluster
- A machine in the cluster which should become the Kubernetes master node with:
- GoLang > 1.2
- make (i.e. build-essential)
- Docker
Note: You can, but you don't have to deploy Kubernetes-Mesos on the same machine the Mesos master is running on.
Deploy Kubernetes-Mesos
Log into the future Kubernetes master node over SSH, replacing the placeholder below with the correct IP address.
ssh jclouds@${ip_address_of_master_node}
Build Kubernetes-Mesos.
$ git clone https://github.com/GoogleCloudPlatform/kubernetes
$ cd kubernetes
$ export KUBERNETES_CONTRIB=mesos
$ make
Set some environment variables.
The internal IP address of the master may be obtained via hostname -i.
$ export KUBERNETES_MASTER_IP=$(hostname -i)
$ export KUBERNETES_MASTER=http://${KUBERNETES_MASTER_IP}:8888
Deploy etcd
Start etcd and verify that it is running:
$ sudo docker run -d --hostname $(uname -n) --name etcd -p 4001:4001 -p 7001:7001 quay.io/coreos/etcd:v2.0.12
$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
fd7bac9e2301 quay.io/coreos/etcd:v2.0.12 "/etcd" 5s ago Up 3s 2379/tcp, 2380/... etcd
It's also a good idea to ensure your etcd instance is reachable by testing it
curl -L http://${KUBERNETES_MASTER_IP}:4001/v2/keys/
If connectivity is OK, you will see an output of the available keys in etcd (if any).
Start Kubernetes-Mesos Services
Update your PATH to more easily run the Kubernetes-Mesos binaries:
$ export PATH="$(pwd)/_output/local/go/bin:$PATH"
Identify your Mesos master: depending on your Mesos installation this is either a host:port like mesos_master:5050 or a ZooKeeper URL like zk://zookeeper:2181/mesos.
In order to let Kubernetes survive Mesos master changes, the ZooKeeper URL is recommended for production environments.
$ export MESOS_MASTER=<host:port or zk:// url>
Create a cloud config file mesos-cloud.conf in the current directory with the following contents:
$ cat <<EOF >mesos-cloud.conf
[mesos-cloud]
mesos-master = ${MESOS_MASTER}
EOF
Now start the kubernetes-mesos API server, controller manager, and scheduler on the master node:
$ km apiserver \
--address=${KUBERNETES_MASTER_IP} \
--etcd-servers=http://${KUBERNETES_MASTER_IP}:4001 \
--service-cluster-ip-range=10.10.10.0/24 \
--port=8888 \
--cloud-provider=mesos \
--cloud-config=mesos-cloud.conf \
--v=1 >apiserver.log 2>&1 &
$ km controller-manager \
--master=${KUBERNETES_MASTER_IP}:8888 \
--cloud-provider=mesos \
--cloud-config=./mesos-cloud.conf \
--v=1 >controller.log 2>&1 &
$ km scheduler \
--address=${KUBERNETES_MASTER_IP} \
--mesos-master=${MESOS_MASTER} \
--etcd-servers=http://${KUBERNETES_MASTER_IP}:4001 \
--mesos-user=root \
--api-servers=${KUBERNETES_MASTER_IP}:8888 \
--v=2 >scheduler.log 2>&1 &
Disown your background jobs so that they'll stay running if you log out.
$ disown -a
Validate KM Services
Interact with the kubernetes-mesos framework via kubectl:
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
# NOTE: your service IPs will likely differ
$ kubectl get services
NAME LABELS SELECTOR IP(S) PORT(S)
k8sm-scheduler component=scheduler,provider=k8sm <none> 10.10.10.113 10251/TCP
kubernetes component=apiserver,provider=kubernetes <none> 10.10.10.1 443/TCP
Lastly, look for Kubernetes in the Mesos web GUI by pointing your browser to
http://<mesos_master_ip:port>. Make sure you have an active VPN connection.
Go to the Frameworks tab, and look for an active framework named "Kubernetes".
Spin up a pod
Write a JSON pod description to a local file:
$ cat <<EOPOD >nginx.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
EOPOD
Send the pod description to Kubernetes using the kubectl CLI:
$ kubectl create -f nginx.yaml
pods/nginx
Wait a minute or two while dockerd downloads the image layers from the internet.
We can use the kubectl interface to monitor the status of our pod:
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 14s
Verify that the pod task is running in the Mesos web GUI. Click on the Kubernetes framework. The next screen should show the running Mesos task that started the Kubernetes pod.
What next?
Try out some of the standard Kubernetes examples.
NOTE: Some examples require Kubernetes DNS to be installed on the cluster. Future work will add instructions to this guide to enable support for Kubernetes DNS.
NOTE: Please be aware that there are known issues with the current Kubernetes-Mesos implementation.