--- assignees: - jdef title: Kubernetes on Mesos --- * TOC {:toc} ## About Kubernetes on Mesos Mesos allows dynamic sharing of cluster resources between Kubernetes and other first-class Mesos frameworks such as [HDFS][1], [Spark][2], and [Chronos][3]. 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][7] and support for centralized logging and monitoring is not yet available. Please [file an issue against the kubernetes-mesos project][8] if you have problems completing the steps below. Further information is available in the Kubernetes on Mesos [contrib directory][13]. ### Prerequisites - Understanding of [Apache Mesos][6] - A running [Mesos cluster on Google Compute Engine][5] - A [VPN connection][10] to the cluster - A machine in the cluster which should become the Kubernetes *master node* with: - Go (see [here](https://git.k8s.io/community/contributors/devel/development.md) for required versions) - 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. ```shell ssh jclouds@${ip_address_of_master_node} ``` Build Kubernetes-Mesos. ```shell git clone https://github.com/kubernetes-incubator/kube-mesos-framework cd kube-mesos-framework make ``` Set some environment variables. The internal IP address of the master may be obtained via `hostname -i`. ```shell export KUBERNETES_MASTER_IP=$(hostname -i) export KUBERNETES_MASTER=http://${KUBERNETES_MASTER_IP}:8888 ``` Note that KUBERNETES_MASTER is used as the api endpoint. If you have existing `~/.kube/config` and point to another endpoint, you need to add option `--server=${KUBERNETES_MASTER}` to kubectl in later steps. ### Deploy etcd Start etcd and verify that it is running: ```shell sudo docker run -d --hostname $(uname -n) --name etcd \ -p 4001:4001 -p 7001:7001 quay.io/coreos/etcd:v2.2.1 \ --listen-client-urls http://0.0.0.0:4001 \ --advertise-client-urls http://${KUBERNETES_MASTER_IP}:4001 ``` ```shell $ sudo docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES fd7bac9e2301 quay.io/coreos/etcd:v2.2.1 "/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 ```shell curl -L http://${KUBERNETES_MASTER_IP}:4001/v2/keys/ ``` If connectivity is OK, you will see an output of the available keys in etcd (if any). ### Start Kubernetes-Mesos Services Update your PATH to more easily run the Kubernetes-Mesos binaries: ```shell export PATH="$(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. ```shell export MESOS_MASTER= ``` Create a cloud config file `mesos-cloud.conf` in the current directory with the following contents: ```shell $ cat <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: ```shell $ 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 \ --secure-port=0 \ --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 \ --cluster-dns=10.10.10.10 \ --cluster-domain=cluster.local \ --v=2 >scheduler.log 2>&1 & ``` Disown your background jobs so that they'll stay running if you log out. ```shell disown -a ``` #### Validate KM Services Interact with the kubernetes-mesos framework via `kubectl`: ```shell $ kubectl get pods NAME READY STATUS RESTARTS AGE ``` ```shell # NOTE: your service IPs will likely differ $ kubectl get services NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE k8sm-scheduler 10.10.10.113 10251/TCP 1d kubernetes 10.10.10.1 443/TCP 1d ``` Lastly, look for Kubernetes in the Mesos web GUI by pointing your browser to `http://`. 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: ```shell $ cat <nginx.yaml ``` ```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: ```shell $ kubectl create -f ./nginx.yaml pod "nginx" created ``` 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: ```shell $ 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. ## Launching kube-dns Kube-dns is an addon for Kubernetes which adds DNS-based service discovery to the cluster. For a detailed explanation see [DNS in Kubernetes][4]. The kube-dns addon runs as a pod inside the cluster. The pod consists of three co-located containers: - a local etcd instance - the [kube-dns][11] DNS server We assume that kube-dns will use - the service IP `10.10.10.10` - and the `cluster.local` domain. Note that we have passed these two values already as parameter to the apiserver above. A template for a replication controller spinning up the pod with the 3 containers can be found at [cluster/addons/dns/kubedns-controller.yaml.in][12] in the repository. The following steps are necessary in order to get a valid replication controller yaml file: - replace `{% raw %}{{ pillar['dns_replicas'] }}{% endraw %}` with `1` - replace `{% raw %}{{ pillar['dns_domain'] }}{% endraw %}` with `cluster.local.` - add `--kube_master_url=${KUBERNETES_MASTER}` parameter to the kube2sky container command. In addition the service template at [cluster/addons/dns/kubedns-controller.yaml.in][12] needs the following replacement: - `{% raw %}{{ pillar['dns_server'] }}{% endraw %}` with `10.10.10.10`. To do this automatically: ```shell{% raw %} sed -e "s/{{ pillar\['dns_replicas'\] }}/1/g;"\ "s,\(command = \"/kube2sky\"\),\\1\\"$'\n'" - --kube_master_url=${KUBERNETES_MASTER},;"\ "s/{{ pillar\['dns_domain'\] }}/cluster.local/g" \ cluster/addons/dns/kubedns-controller.yaml.in > kubedns-controller.yaml sed -e "s/{{ pillar\['dns_server'\] }}/10.10.10.10/g" \ cluster/addons/dns/kubedns-svc.yaml.in > kubedns-svc.yaml ``` Now the kube-dns pod and service are ready to be launched: ```shell kubectl create -f ./kubedns-controller.yaml kubectl create -f ./kubedns-svc.yaml ``` Check with `kubectl get pods --namespace=kube-system` that 3/3 containers of the pods are eventually up and running. Note that the kube-dns pods run in the `kube-system` namespace, not in `default`. To check that the new DNS service in the cluster works, we start a busybox pod and use that to do a DNS lookup. First create the `busybox.yaml` pod spec: ```shell cat <busybox.yaml ``` ```yaml apiVersion: v1 kind: Pod metadata: name: busybox namespace: default spec: containers: - image: busybox command: - sleep - "3600" imagePullPolicy: IfNotPresent name: busybox restartPolicy: Always EOF ``` Then start the pod: ```shell kubectl create -f ./busybox.yaml ``` When the pod is up and running, start a lookup for the Kubernetes master service, made available on 10.10.10.1 by default: ```shell kubectl exec busybox -- nslookup kubernetes ``` If everything works fine, you will get this output: ```shell Server: 10.10.10.10 Address 1: 10.10.10.10 Name: kubernetes Address 1: 10.10.10.1 ``` ## Support Level IaaS Provider | Config. Mgmt | OS | Networking | Docs | Conforms | Support Level -------------------- | ------------ | ------ | ---------- | --------------------------------------------- | ---------| ---------------------------- Mesos/GCE | | | | [docs](/docs/getting-started-guides/mesos) | | Community ([Kubernetes-Mesos Authors](https://github.com/mesosphere/kubernetes-mesos/blob/master/AUTHORS.md)) For support level information on all solutions, see the [Table of solutions](/docs/getting-started-guides/#table-of-solutions) chart. ## What next? Try out some of the standard [Kubernetes examples][9]. Read about Kubernetes on Mesos' architecture in the [contrib directory][13]. **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][7]. [1]: https://docs.mesosphere.com/latest/usage/service-guides/hdfs/ [2]: https://docs.mesosphere.com/latest/usage/service-guides/spark/ [3]: https://docs.mesosphere.com/latest/usage/service-guides/chronos/ [4]: https://releases.k8s.io/{{page.githubbranch}}/cluster/addons/dns/README.md [5]: https://dcos.io/docs/latest/administration/installing/cloud/gce/ [6]: http://mesos.apache.org/ [7]: https://github.com/kubernetes-incubator/kube-mesos-framework/blob/master/docs/issues.md [8]: https://github.com/mesosphere/kubernetes-mesos/issues [9]: https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/examples [10]: http://open.mesosphere.com/getting-started/cloud/google/mesosphere/#vpn-setup [11]: https://git.k8s.io/kubernetes/cluster/addons/dns/README.md#kube-dns [12]: https://git.k8s.io/kubernetes/cluster/addons/dns/kubedns-controller.yaml.in [13]: https://github.com/kubernetes-incubator/kube-mesos-framework/blob/master/README.md