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https://github.com/mhausenblas/mehdb
Educational Kubernetes-native NoSQL datastore using StatefulSet and persistent volumes
https://github.com/mhausenblas/mehdb
kubernetes persistent-volume stateful statefulsets
Last synced: 3 months ago
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Educational Kubernetes-native NoSQL datastore using StatefulSet and persistent volumes
- Host: GitHub
- URL: https://github.com/mhausenblas/mehdb
- Owner: mhausenblas
- License: apache-2.0
- Created: 2018-06-19T07:29:14.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2021-02-14T14:28:14.000Z (over 3 years ago)
- Last Synced: 2024-07-23T21:08:37.797Z (4 months ago)
- Topics: kubernetes, persistent-volume, stateful, statefulsets
- Language: Go
- Homepage:
- Size: 16.6 KB
- Stars: 23
- Watchers: 3
- Forks: 13
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-cloud-native - mehdb - Educational Kubernetes-native NoSQL datastore using StatefulSet and persistent volumes. (Database)
README
# mehdb
This is `mehdb`, an educational Kubernetes-native NoSQL data store. It is not meant for production usage but purely to learn and experiment with [StatefulSets](https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/).
## Usage
Deploy it:
```bash
$ kubectl create ns mehdb
$ kubectl -n=mehdb apply -f app.yaml
```
Access it from within the cluster:
```
$ kubectl -n=mehdb run -i -t --rm jumpod --restart=Never --image=quay.io/mhausenblas/jump:0.2 -- sh
$ echo "test data" > /tmp/test
$ curl -L -XPUT -T /tmp/test mehdb:9876/set/test
$ curl mehdb:9876/get/test
$ curl mehdb-1.mehdb:9876/get/test
```
Scale to 3 shards (1 leader, 2 followers):
```bash
$ kubectl -n=mehdb scale sts mehdb --replicas=4
```
Clean up:
```bash
$ kubectl -n=mehdb delete sts/mehdb
$ kubectl -n=mehdb delete pvc/data-mehdb-0
$ kubectl -n=mehdb delete pvc/data-mehdb-1
$ kubectl -n=mehdb delete svc/mehdb
```
Note: I tested it in OpenShift Online with Kubernetes in version 1.9 and the setup assumes that a storage class `ebs` exists.
## API
Once deployed you can use `mehdb` to store and retrieve data. Keep the following in mind:
- The keys are restricted, that is, they must match `[a-z]+`. For example, `abc` is a valid key, `123` or `_mykey42` is not.
- The leader shard accepts both reads and writes, a follower shard will redirect to the leader shard if you attempt a write operation.
The following public endpoints are available:
`/get/$KEY` … a HTTP `GET` at this endpoint retrieves the payload available under the key `$KEY` or a `404` if the key does not exist.
`/set/$KEY` … a HTTP `PUT` at this endpoint stores the payload provided under the key `$KEY`.
`/status` … by default returns a `200` and the role (leader or follower), which can be used for a liveness probe, with `?level=full` it returns a `200` and the number of keys it can serve, which can be used for a readiness probe.
## Local development
Run a leader shard like so:
```bash
$ MEHDB_HOST=mehdb-0 MEHDB_PORT=9999 go run main.go
```
Run a follower shard like so:
```bash
$ MEHDB_LOCAL=yes MEHDB_DATADIR=./follower-data go run main.go
```
Now you can for example write to and/or read from the leader:
```bash
$ http PUT localhost:9999/set/abc < test/somedata
$ http localhost:9999/get/abc
```
Also, you can read from the follower:
```bash
$ http localhost:9876/get/abc
```
If you try to write to the follower, you'll be redirected:
```bash
$ http PUT localhost:9876/set/abc < test/somedata
HTTP/1.1 307 Temporary Redirect
Content-Length: 0
Date: Tue, 19 Jun 2018 12:28:57 GMT
Location: http://localhost:9999/set/abc
```