# Multi cluster installation

## Introduction

Multi Cluster installation is an important features for production deployments.

Most of the project are using the Kubernetes as undercloud orchestration. So deploying multi cluster for the multi cloud region should be maintained by Kubernetes

This section explains how to deploy the Multi cluster of Kubernetes from a containerized KUD running as a Kubernetes Job.

## How it works

KUD installation installer is divided into two regions with args - `--install-pkg` and `--cluster <cluster-name>`

### Args
**--install-pkg** - Installs packages required to run installer script itself inside a container and kubespray packages

**--cluster < cluster-name >** - Installs k8s cluster, addons and plugins and store the artifacts in the host machine

### Internal Mechanism

* Container image is build using the `installer --install-pkg` arg and Kubernetes job is used to install the cluster using `installer --cluster <cluster-name>`. Installer will invoke the kubespray cluster.yml, kud-addsons and plugins ansible cluster.

Installer script finds the `hosts.init` for each cluster in `/opt/multi-cluster/<cluster-name>`

Kubernetes jobs(a cluster per job) are used to install multiple clusters and logs of each cluster deployments are stored in the `/opt/kud/multi-cluster/<cluster-name>/logs` and artifacts are stored as follows `/opt/kud/multi-cluster/<cluster-name>/artifacts`

## Quickstart Installation Guide

Build the kud docker images as follows, add KUD_ENABLE_TESTS & KUD_PLUGIN_ENABLED for the testing only:

```
$ git clone https://github.com/onap/multicloud-k8s.git && cd multicloud-k8s
$  docker build  --rm \
	--build-arg http_proxy=${http_proxy} \
	--build-arg HTTP_PROXY=${HTTP_PROXY} \
	--build-arg https_proxy=${https_proxy} \
	--build-arg HTTPS_PROXY=${HTTPS_PROXY} \
	--build-arg no_proxy=${no_proxy} \
	--build-arg NO_PROXY=${NO_PROXY} \
        --build-arg KUD_ENABLE_TESTS=true \
        --build-arg KUD_PLUGIN_ENABLED=true \
	-t github.com/onap/multicloud-k8s:latest . -f build/Dockerfile
```
Let's create a cluster-101 and cluster-102 hosts.ini as follows

```
$ mkdir -p /opt/kud/multi-cluster/{cluster-101,cluster-102}
```

Create hosts.ini as follows in the direcotry cluster-101(c01 IP address 10.10.10.3) and cluster-102(c02 IP address 10.10.10.5)

```
/opt/kud/multi-cluster/cluster-101/hosts.ini
[all]
c01 ansible_ssh_host=10.10.10.5 ansible_ssh_port=22

[kube-master]
c01

[kube-node]
c01

[etcd]
c01

[ovn-central]
c01

[ovn-controller]
c01

[virtlet]
c01

[k8s-cluster:children]
kube-node
kube-master
```
Do the same for the cluster-102 with c01 and IP address 10.10.10.5.

Create the ssh secret for Baremetal or VM based on your deployment. and Launch the kubernetes job as follows
```
$ kubectl create secret generic ssh-key-secret --from-file=id_rsa=/root/.ssh/id_rsa --from-file=id_rsa.pub=/root/.ssh/id_rsa.pub
$ CLUSTER_NAME=cluster-101
$ cat <<EOF | kubectl create -f -
apiVersion: batch/v1
kind: Job
metadata:
  name: kud-$CLUSTER_NAME
spec:
  template:
    spec:
      hostNetwork: true
      containers:
        - name: kud
          image: github.com/onap/multicloud-k8s:latest
          imagePullPolicy: IfNotPresent
          volumeMounts:
          - name: multi-cluster
            mountPath: /opt/kud/multi-cluster
          - name: secret-volume
            mountPath: "/.ssh"
          command: ["/bin/sh","-c"]
          args: ["cp -r /.ssh /root/; chmod -R 600 /root/.ssh; ./installer --cluster $CLUSTER_NAME --plugins onap4k8s"]
          securityContext:
            privileged: true
      volumes:
      - name: multi-cluster
        hostPath:
          path: /opt/kud/multi-cluster
      - name: secret-volume
        secret:
          secretName: ssh-key-secret
      restartPolicy: Never
  backoffLimit: 0

EOF
```

Multi - cluster information from the host machine;

```
$ kubectl --kubeconfig=/opt/kud/multi-cluster/cluster-101/artifacts/admin.conf cluster-info
Kubernetes master is running at https://192.168.121.2:6443
coredns is running at https://192.168.121.2:6443/api/v1/namespaces/kube-system/services/coredns:dns/proxy
kubernetes-dashboard is running at https://192.168.121.2:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
$ kubectl --kubeconfig=/opt/kud/multi-cluster/cluster-102/artifacts/admin.conf cluster-info
Kubernetes master is running at https://192.168.121.6:6443
coredns is running at https://192.168.121.6:6443/api/v1/namespaces/kube-system/services/coredns:dns/proxy
kubernetes-dashboard is running at https://192.168.121.6:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
```


## License

Apache-2.0