mirror of https://github.com/k3s-io/k3s
136 lines
4.9 KiB
Markdown
136 lines
4.9 KiB
Markdown
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 0**
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change the namespace of the current context to "rethinkdb"
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```
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$kubectl config view -o template --template='{{index . "current-context"}}' | xargs -I {} kubectl config set-context {} --namespace=rethinkdb
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```
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**Step 1**
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antmanler/rethinkdb will discover peer using endpoints provided by kubernetes_ro service,
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so first create a service so the following pod can query its endpoint
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```shell
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$kubectl create -f driver-service.yaml
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```
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check out:
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```shell
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$kubectl get se
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NAME LABELS SELECTOR IP(S) PORT(S)
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rethinkdb-driver db=influxdb db=rethinkdb 10.0.27.114 28015/TCP
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```
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**Step 2**
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start fist server in cluster
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```shell
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$kubectl create -f 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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```shell
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$kubectl get po
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POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
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rethinkdb-rc-1.16.0-6odi0 kubernetes-minion-s59e/ db=rethinkdb,role=replicas Pending 11 seconds
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rethinkdb antmanler/rethinkdb:1.16.0
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```
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**Done!**
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---
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Scale
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-----
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You can scale up you cluster using `kubectl resize`, and new pod will join to exsits cluster automatically, for example
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```shell
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$kubectl resize rc rethinkdb-rc-1.16.0 --replicas=3
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resized
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$kubectl get po
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POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
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rethinkdb-rc-1.16.0-6odi0 10.244.3.3 kubernetes-minion-s59e/104.197.79.42 db=rethinkdb,role=replicas Running About a minute
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rethinkdb antmanler/rethinkdb:1.16.0 Running About a minute
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rethinkdb-rc-1.16.0-e3mxv kubernetes-minion-d7ub/ db=rethinkdb,role=replicas Pending 6 seconds
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rethinkdb antmanler/rethinkdb:1.16.0
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rethinkdb-rc-1.16.0-manu6 kubernetes-minion-cybz/ db=rethinkdb,role=replicas Pending 6 seconds
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rethinkdb antmanler/rethinkdb:1.16.0
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```
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Admin
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-----
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You need a separate pod (which labled as role:admin) to access Web Admin UI
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```shell
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kubectl create -f admin-pod.yaml
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kubectl create -f admin-service.yaml
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```
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find the service
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```shell
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$kubectl get se
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NAME LABELS SELECTOR IP(S) PORT(S)
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rethinkdb-admin db=influxdb db=rethinkdb,role=admin 10.0.131.19 8080/TCP
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104.197.19.120
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rethinkdb-driver db=influxdb db=rethinkdb 10.0.27.114 28015/TCP
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```
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We request for an external load balancer in the admin-service.yaml file:
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```
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createExternalLoadBalancer: true
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```
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The external load balancer allows us to access the service from outside via an external IP, which is 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 GCE:
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```
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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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* All services and pods are placed under namespace `rethinkdb`.
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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](https://github.com/GoogleCloudPlatform/kubernetes/tree/master/examples/node-selection)
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* see [antmanler/rethinkdb-k8s](https://github.com/antmanler/rethinkdb-k8s) for detail
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[]()
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