131 lines
3.8 KiB
Markdown
131 lines
3.8 KiB
Markdown
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RethinkDB Cluster on Kubernetes
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==============================
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Setting up a [rethinkdb](http://rethinkdb.com/) cluster on [kubernetes](http://kubernetes.io)
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**Features**
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* Auto configuration cluster by querying info from k8s
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* Simple
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Quick start
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-----------
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**Step 1**
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Rethinkdb will discover its peer using endpoints provided by kubernetes service,
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so first create a service so the following pod can query its endpoint
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```sh
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$kubectl create -f examples/storage/rethinkdb/driver-service.yaml
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```
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check out:
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```sh
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$kubectl get services
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NAME CLUSTER_IP EXTERNAL_IP PORT(S) SELECTOR AGE
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rethinkdb-driver 10.0.27.114 <none> 28015/TCP db=rethinkdb 10m
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[...]
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```
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**Step 2**
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start the first server in the cluster
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```sh
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$kubectl create -f examples/storage/rethinkdb/rc.yaml
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```
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Actually, you can start servers as many as you want at one time, just modify the `replicas` in `rc.ymal`
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check out again:
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```sh
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$kubectl get pods
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NAME READY REASON RESTARTS AGE
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[...]
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rethinkdb-rc-r4tb0 1/1 Running 0 1m
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```
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**Done!**
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---
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Scale
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-----
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You can scale up your cluster using `kubectl scale`. The new pod will join to the existing cluster automatically, for example
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```sh
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$kubectl scale rc rethinkdb-rc --replicas=3
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scaled
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$kubectl get pods
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NAME READY REASON RESTARTS AGE
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[...]
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rethinkdb-rc-f32c5 1/1 Running 0 1m
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rethinkdb-rc-m4d50 1/1 Running 0 1m
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rethinkdb-rc-r4tb0 1/1 Running 0 3m
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```
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Admin
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-----
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You need a separate pod (labeled as role:admin) to access Web Admin UI
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```sh
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kubectl create -f examples/storage/rethinkdb/admin-pod.yaml
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kubectl create -f examples/storage/rethinkdb/admin-service.yaml
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```
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find the service
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```console
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$kubectl get services
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NAME CLUSTER_IP EXTERNAL_IP PORT(S) SELECTOR AGE
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[...]
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rethinkdb-admin 10.0.131.19 104.197.19.120 8080/TCP db=rethinkdb,role=admin 10m
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rethinkdb-driver 10.0.27.114 <none> 28015/TCP db=rethinkdb 20m
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```
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We request an external load balancer in the [admin-service.yaml](admin-service.yaml) file:
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```
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type: LoadBalancer
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```
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The external load balancer allows us to access the service from outside the firewall via an external IP, 104.197.19.120 in this case.
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Note that you may need to create a firewall rule to allow the traffic, assuming you are using Google Compute Engine:
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```console
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$ gcloud compute firewall-rules create rethinkdb --allow=tcp:8080
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```
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Now you can open a web browser and access to *http://104.197.19.120:8080* to manage your cluster.
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**Why not just using pods in replicas?**
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This is because kube-proxy will act as a load balancer and send your traffic to different server,
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since the ui is not stateless when playing with Web Admin UI will cause `Connection not open on server` error.
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- - -
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**BTW**
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* `gen_pod.sh` is using to generate pod templates for my local cluster,
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the generated pods which is using `nodeSelector` to force k8s to schedule containers to my designate nodes, for I need to access persistent data on my host dirs. Note that one needs to label the node before 'nodeSelector' can work, see this [tutorial](../../../docs/user-guide/node-selection/)
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* see [antmanler/rethinkdb-k8s](https://github.com/antmanler/rethinkdb-k8s) for detail
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<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
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[]()
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<!-- END MUNGE: GENERATED_ANALYTICS -->
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