How to Use Helm Chart to Deploy Distributed GreptimeDB on Kubernetes
Tags: database, kubernetes, distributedsystems, greptime
Published: 2023-12-21 03:00:07

[GreptimeDB](https://github.com/GreptimeTeam/greptimedb) as a time-series database for the cloud era, has embraced cloud-native technology from day one. Deploying databases on Kubernetes offers scalability, self-healing, and simplified deployment and management, thereby providing robust elasticity and reliability for applications.

[Helm](https://helm.sh/) is a package manager for managing Kubernetes applications. By using Helm Charts, applications can be easily packaged, configured, and deployed to Kubernetes clusters.

This article explains how to deploy distributed GreptimeDB using Helm Chart and store data on object storage such as AWS S3. Of course, you can also deploy standalone GreptimeDB, navigate to [this article](https://www.greptime.com/blogs/2023-12-12-helm-chart) to learn more.

## Configure the Helm Chart Environment

First, you need to install the Helm tool, which can be done following the instructions in the [installation document](https://helm.sh/docs/intro/install/).

Before deploying the application, add the [greptime repository](https://github.com/GreptimeTeam/helm-charts) to Helm, which contains a series of available Helm Charts.

Use the following commands to add the greptime repository to Helm:

```shell
helm repo add greptime https://greptimeteam.github.io/helm-charts/
helm repo update
```

Use the following commands to view the greptime Helm Charts available:

```shell
helm search repo greptime --devel -l
```

## Install Charts
### 2.1 Install `etcd`

```shell
helm install etcd oci://registry-1.docker.io/bitnamicharts/etcd \
  --set replicaCount=1 \
  --set auth.rbac.create=false \
  --set auth.rbac.token.enabled=false \
  -n default
```

### 2.2 Install `greptimedb-operator`

```shell
helm install mycluster greptime/greptimedb-cluster -n default
```

### 2.3 Install `greptimedb-cluster`

```shell
helm install mycluster greptime/greptimedb-cluster -n default
```

To install a specific version of the chart, use:

```shell
helm install mycluster greptime/greptimedb-cluster -n default --version <chart-version>
```

View the pods installed using the `kubectl` command line tool:

```shell
kubectl get po -n default
NAME                                   READY   STATUS    RESTARTS   AGE
etcd-0                                 1/1     Running   0          2m18s
greptimedb-operator-546b5f9656-tz9gn   1/1     Running   0          2m1s
mycluster-datanode-0                   1/1     Running   0          32s
mycluster-datanode-1                   1/1     Running   0          27s
mycluster-datanode-2                   1/1     Running   0          21s
mycluster-frontend-76cbf55687-4drvx    1/1     Running   0          15s
mycluster-meta-6b7974464b-bbt4h        1/1     Running   0          33s
```

### 2.4 Unload `greptimedb-cluster`

```shell
helm uninstall mycluster -n default
```

## Store Data on AWS S3
In a previous tutorial, we shared how to run the GreptimeDB binary and save data to AWS S3. Similarly, we can also deploy GreptimeDB in a containerized manner and store data in the cloud, achieving greater elasticity and reliability.

The detailed steps are as follows:

```shell
helm install mycluster greptime/greptimedb-cluster \
  --set storage.s3.bucket="your-bucket" \
  --set storage.s3.region="region-of-bucket" \
  --set storage.s3.root="/greptimedb-data" \
  --set storage.credentials.secretName="s3-credentials" \
  --set storage.credentials.accessKeyId="your-access-key-id" \
  --set storage.credentials.secretAccessKey="your-secret-access-key"
```

You can adjust the parameters to your S3 information:
- bucket: S3 Bucket Name
- region: S3 Bucket Region
- root: Data storage directory, set here as `/greptimedb-data`
- secretName: S3 Credentials Secret Name
- accessKeyId: AWS Access Key ID
- secretAccessKey: AWS Secret Access Key

After the pod starts running, perform a test to write data into S3:

```shell
kubectl port-forward svc/mycluster-frontend 4002:4002 > a.out &
```

Connect to GreptimeDB using MySQL protocol:

```shell
mysql -h 127.0.0.1 -P 4002
```

Execute the create table statement. Here the table name is `s3_test_table`:

```sql
CREATE TABLE s3_test_table (
  host STRING,
  idc STRING,
  cpu_util DOUBLE,
  memory_util DOUBLE,
  disk_util DOUBLE,
  ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY(host, idc),
  TIME INDEX(ts)
);
```

Insert data into `s3_test_table`：

```sql
INSERT INTO s3_test_table
VALUES
    ("host1", "idc_a", 11.8, 10.3, 10.3, 1667446797450),
    ("host1", "idc_a", 80.1, 70.3, 90.0, 1667446797550),
    ("host1", "idc_b", 50.0, 66.7, 40.6, 1667446797650),
    ("host1", "idc_b", 51.0, 66.5, 39.6, 1667446797750),
    ("host1", "idc_b", 52.0, 66.9, 70.6, 1667446797850),
    ("host1", "idc_b", 53.0, 63.0, 50.6, 1667446797950),
    ("host1", "idc_b", 78.0, 66.7, 20.6, 1667446798050),
    ("host1", "idc_b", 68.0, 63.9, 50.6, 1667446798150),
    ("host1", "idc_b", 90.0, 39.9, 60.6, 1667446798250);
```

You can now log into the AWS S3 console to view the data that has been inserted:


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/8c3t9j6hsmkg55ot7lum.png)

You can also access GreptimeDB through the [Dashboard](https://github.com/GreptimeTeam/dashboard):

```shell
kubectl port-forward svc/mycluster-frontend 4000:4000 > a.out &
```

Visit `http://localhost:4000/dashboard/query` in your browser to view the Dashboard, and execute `select * from s3_test_table;` to view the data that has been written.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/hxit06wab43lyqmu2igg.png)

Unload `greptimedb-cluster`:

```shell
helm uninstall mycluster -n default
```

## Summary
This article has provided a comprehensive guide on deploying distributed GreptimeDB using Helm Chart, with a focus on configuring data storage solutions using AWS S3. This approach, particularly relevant in the cloud-native era, significantly enhances the flexibility and reliability of data management while streamlining both deployment and management processes.