Ingest MQTT Data into GreptimeDB

GreptimeDB is an open-source time-series database with a special focus on scalability, analytical capabilities and efficiency. It's designed to work on the infrastructure of the cloud era, and users benefit from its elasticity and commodity storage. EMQX Platform now supports connection to mainstream versions of GreptimeDB, GreptimeCloud or GreptimeDB Enterprise.

This page provides a comprehensive introduction to the data integration between the EMQX Platform and GreptimeDB with practical instructions on creating and validating the data integration.

How It Works

GreptimeDB data integration is a built-in feature in the EMQX Platform that combines the real-time data capturing and transmission capabilities of the EMQX Platform with the data storage and analysis capabilities of GreptimeDB. With a built-in rule engine component, the integration simplifies the process of ingesting data from the EMQX Platform to GreptimeDB for storage and analysis, eliminating the need for complex coding. The workflow is as follows:

The diagram below illustrates a typical architecture of data integration between the EMQX Platform and GreptimeDB:

1. Message publication and reception: Industrial devices establish successful connections to EMQX Platform through the MQTT protocol and regularly publish energy consumption data using the MQTT protocol. This data includes production line identifiers and energy consumption values. When EMQX Platform receives these messages, it initiates the matching process within its rules engine.
2. Rule Engine Processes Messages: The built-in rule engine processes messages from specific sources based on topic matching. When a message arrives, it passes through the rule engine, which matches it with corresponding rules and processes the message data. This can include transforming data formats, filtering specific information, or enriching messages with context information.
3. Data ingestion into GreptimeDB: Rules defined in the rule engine trigger operations to write messages to GreptimeDB. The GreptimeDB action provides Line Protocol templates that allow flexible definitions of the data format to write specific message fields to the corresponding tables and columns in GreptimeDB.

After energy consumption data is written to GreptimeDB, you can flexibly use SQL statements or Prometheus query language to analyze the data. For example:

• Connect to visualization tools such as Grafana to generate charts and display energy consumption data.
• Connect to application systems such as ERP for production analysis and production plan adjustments.
• Connect to business systems to perform real-time energy usage analysis, facilitating data-driven energy management.

Features and Benefits

The data integration with GreptimeDB brings the following features and advantages to your business:

• Ease of Use: EMQX Platform and GreptimeDB both offer a user-friendly experience in development. EMQX Platform provides the standard MQTT protocol along with ready-to-use various authentication, authorization, and clustering features. GreptimeDB offers user-friendly designs like Time-Series Tables and schemaless architecture. The integration of both can accelerate the process of business integration and development.
• Efficient Data Handling: EMQX Platform can handle a large number of IoT device connections and message throughput efficiently. GreptimeDB excels in data writing, storage, and querying, meeting the data processing needs of IoT scenarios without overwhelming the system.
• Message Transformation: Messages can undergo rich processing and transformation within EMQX Platform rules before being written to GreptimeDB.
• Efficient Storage and Scalability: EMQX Platform and GreptimeDB both have cluster scaling capabilities, allowing flexible horizontal scaling as your business grows to meet expanding demands.
• Advanced Querying Capabilities: GreptimeDB provides optimized functions, operators, and indexing techniques for efficient querying and analysis of timestamp data, enabling precise insights to be extracted from IoT time-series data.

Before You Start

This section describes the preparations you need to complete before you start to create a GreptimeDB data integration, including how to install a GreptimeDB server.

Prerequisites

• Knowledge about data integration
• Knowledge about EMQX Platform data integration rules

Set up Network

Before you start, you need to create a deployment (EMQX cluster) on the EMQX Platform and configure the network.

• For Dedicated/Premium deployment users: First, create a VPC Peering Connection. After establishing the peering connection, you can log in to the Platform Console via the internal network IP to access the target connector. Alternatively, set up a NAT Gateway to access the target connector through a public IP.
• For BYOC (Bring Your Own Cloud) deployment users: Establish a peering connection between the VPC where BYOC is deployed and the VPC where the target connector is located. After creating the peering connection, you can access the target connector via the internal network IP. If you need to access resources via a public IP address, configure a NAT gateway for the VPC where BYOC is deployed in the public cloud console.

Install GreptimeDB Server

1. Install GreptimeDB via Docker, and then run the docker image.

   # TO start the GreptimeDB docker image
   docker run -p 4000-4004:4000-4004 \
   -p 4242:4242 -v "$(pwd)/greptimedb:/tmp/greptimedb" \
   --name greptime --rm \
   greptime/greptimedb standalone start \
   --http-addr 0.0.0.0:4000 \
   --rpc-addr 0.0.0.0:4001 \
   --mysql-addr 0.0.0.0:4002 \
   --user-provider=static_user_provider:cmd:greptime_user=greptime_pwd

2. The user-provider parameter configures the GreptimeDB authentication. You can configure it by file. For more information, refer to the documentation.

3. With GreptimeDB running, visit http://localhost:4000/dashboard to use the GreptimeDB dashboard. The username and password are greptime_user and greptime_pwd.

Create a Connector

Before creating data integration rules, you need to first create a GreptimeDB connector to access the GreptimeDB server.

1. Go to your deployment. Click Data Integration from the left-navigation menu. If it is the first time for you to create a connector, select GreptimeDB under the Data Persistence category. If you have already created connectors, select New Connector and then select GreptimeDB under the Data Persistence category.

2. Connector Name: The system will automatically generate a connector name.

3. Enter the connection information:

   • Server Host: Enter {host}:4001. If you are creating a connection to GreptimeCloud, use 443 as the port by entering {url}:443.
   • Database: Enter public. If you are connecting to GreptimeCloud, enter the service name instead.
   • Username and Password: Enter greptime_user and greptime_pwd, which are set in the Install GreptimeDB Server. If you are connecting to GreptimeCloud, enter the service username and password.
   • Enable TLS: If you want to establish an encrypted connection, click the toggle switch.
   • Configure advanced settings according to your business needs (optional).

4. Click the Test button. If the GreptimeDB service is accessible, a prompt indicating connector available will be returned.

5. Click the New button to complete the creation.

Create a Rule

This section demonstrates how to create a GreptimeDB Rule and add action to the rule via the EMQX Platform Console.

1. Click New Rule in the Rules area or click the New Rule icon in the Actions column of the connector you just created.

2. Set the rules in the SQL Editor based on the feature to use, Our goal is to trigger the engine when the client sends a temperature and humidity message to the temp_hum/emqx topic. Here you need a certain process of SQL:

    SELECT
     timestamp, clientid, payload
    FROM
      "temp_hum/emqx"

   TIP

   If you are a beginner user, click SQL Examples and Enable Test to learn and test the SQL rule.

3. Click Next to add an action.

4. Select the connector you just created from the Connector dropdown box.

5. Configure Write Syntax. Specify a text-based format that provides the measurement, tags, fields, and timestamp of a data point, and placeholder supported according to the InfluxDB line protocol syntax. GreptimeDB supports data formats compatible with InfluxDB. This tutorial examples syntax:

    myMeasurement,tag1=${clientid} fieldKey=${payload}

TIP

• To write a signed integer type value to GreptimeDB, add i as the type identifier after the placeholder, for example, ${payload.int}i.
• To write an unsigned integer type value to GreptimeDB, add u as the type identifier after the placeholder, for example, ${payload.int}u.

6. Specify the Time Precision: Select millisecond by default.

7. Expand Advanced Settings to configure Sync/Async mode, queue and batch, and other parameters as appropriate Advanced Settings Options (optional)

8. Click the Confirm button to complete the rule creation.

9. In the Successful new rule pop-up, click Back to Rules, thus completing the entire data integration configuration chain.

Test the Rule

You are recommended to use MQTTX to simulate temperature and humidity data reporting, but you can also use any other client.

1. Use MQTTX to connect to the deployment and send messages to the following Topic.

   • topic: temp_hum/emqx

   • client id: test_client

   • payload:

     {
       "temp": "27.5",
       "hum": "41.8"
     }

2. Check the running status of the rule, there should be one new incoming and one new outgoing message.

3. In the GreptimeDB dashboard, you can confirm whether the message is written into the GreptimeDB via SQL.