Integrate with InfluxDB

Step 1: Create an application function

1. Download the function code package fcApp_influxdb_v1.0.zip.
2. Log on to the Function Compute console.
   If you have not activated this service, read the terms and select I have read and agree to the terms. Then, click Activate Now.
3. (Optional) In the navigation pane on the left, click Services & Functions. On the Services & Functions page, in the Service List section, click Create Service to create a service.
   The Service Name parameter is required. Set this parameter to EdgeFC. You can configure the other parameters as needed or use their default settings.

   Note

   • If this is your first time creating a service in Function Compute, follow the configuration wizard.
   • If you have already created the EdgeFC service for other scenarios or miniprogram examples, you do not need to create it again.
4. After the service is created, on the Services & Functions page, find the EdgeFC service and click Create Function.
5. On the Create Function page, click Configure and Deploy in the Event Function section.
6. Set the basic configuration parameters for the function.

   Parameter	Description
   Function Type	Keep the default option.
   Service	Select the EdgeFC service that you created.
   Function Name	Set this to influxdbStore.
   Runtime	Set the runtime environment for the function and select a method to upload the code. In this example, select Python 3. To the right of Upload Code, select Upload Code Package. Click Upload Code and upload the fcApp_influxdb_v1.0.zip package that you downloaded in Step 1.
   Handler	Use the default value: index.handler.

   You can configure the other parameters as needed or use their default settings. For more information, see Function Compute.

   After you confirm the function information, click Create.

7. After the function is created, you are redirected to the function details page. On the Code Execution tab, in the Code Execution Management section, select the Online Edit radio button to view the source code.
   

   Note The sample code for `influxdbStore` performs the following three steps.

   1. Parses the `ProductKey`, `DeviceName`, and `attribute` from the received device data, which is the `event` parameter.

      event_json = json.loads(event)
      if(event_json["topic"].startswith('/sys'))
        pk, dn, attribute = parseTopic(event_json['topic'])

   2. Parses the payload, which contains the device properties or events.

      
      payload_json = json.loads(event_json["payload"])

   3. Encapsulates the property or event data into the InfluxDB storage format. For more information about the data format, see Appendix: Data format definition in this topic. This step uses the InfluxDB client API for Python.

Step 2: Assign the function to an edge instance

1. Log on to the IoT Edge console.
2. In the navigation pane on the left, click Application Management.
3. Create a Function Compute edge application that uses the function that you created in Step 1. For more information, see Function Compute application.

   The application information parameters are as follows:

   Parameter	Description
   Application name	Set a name for your application, such as influxdbStore.
   Application type	Select Function Compute.
   Region	Select the region where you created the service.
   Service	Select the EdgeFC service.
   Function	Select the influxdbStore function.
   Authorization	Select AliyunIOTAccessingFCRole.
   Application version	Set a version for the application. The version number must be unique for this application. You cannot set the same version number for two versions of the same application.

   The following describes the function configuration:

   Parameter	Description
   Enable default configurations	Select No.
   Run mode	There are two run modes. Select Keep running. The program runs immediately after it is deployed.
   Timeout (seconds)	The maximum processing time for a function after it receives an event. Use the default value of 5 seconds. If the function does not return a result within this time, the Function Compute program is forcibly restarted.
   Scheduled run	Use the default configuration: Off.
   Environment variable	Click Add Environment Variable and add the environment variables shown in the Environment variable configuration table below.

   Table 3. Environment variable configuration

   Name	Value
   host	The endpoint of InfluxDB.
   port	The access port of InfluxDB. The default value is 8086.
   username	The username for InfluxDB. The default value is root.
   password	The password for InfluxDB. The default value is root.
   database	The database name in InfluxDB. The default value is example.

   You do not need to configure any other parameters.

4. In the navigation pane on the left, click Edge Instances.
5. Find the edge instance that you created in the "Prerequisites" section and click View.
6. On the Instance Details page, go to the Edge Applications tab and click Assign Application.
7. In the Assign Application panel, find the influxdbStore application that you created, click Assign in the Actions column, and then click Close.

Step 3: Configure message routing

This topic explains how to add messages and describes each parameter. For more information, see Set message routing.

1. On the Instance Details page, select the Message Routing tab and click Add Route to add a message route from the LightSensor device to Function Compute.
2. Set the following parameters. Then, click Confirm.

   Parameter	Description
   Route Name	Set a name for the message route.
   Message Source	Select Device. Then, select Light Sensor > LightSensor.
   Topic Filter	Select All.
   Message Target	Select Edge Application and the EdgeFC/influxdbStore function.

Step 4: Deploy the edge instance

1. On the Instance Details page, click Deploy in the upper-right corner. In the dialog box that appears, click OK to deploy resources, such as sub-devices and functions, to the edge.
2. Log on to your gateway using Secure Shell (SSH). Run the tail -f /linkedge/run/logger/fc-base/influxdbStore/log.INFO command to view the function logs and monitor its status.
   

Appendix: Data query

After the data is stored in InfluxDB, you can query it using the InfluxDB API. The following examples show how to query data. For more information, see the InfluxDB API documentation.

• Query by product to retrieve the values of a property at all points in time. The response lists all stored property values in chronological order.

  curl -G 'http://localhost:8086/query?db=example&u=root&p=root' --data-urlencode "epoch=ms" --data-urlencode 'q=SELECT * FROM "Unique property identifier (unique within the product)" WHERE "_productKey" = $pk and "_dataType" = $type' --data-urlencode 'params={"pk":"ProductKey of the product", "type": "property"}'
  
  // Response
  {
      "results": [{
          "statement_id": 0,
          "series": [{
              "name": "temp",
              "columns": ["time", "_dataType", "_deviceName", "_productKey", "value"],
              "values": [
                  [1570782663561, "property", "0987654321", "ProductKey of the product", 100.1],
                  [1570782688527, "property", "0987654321", "ProductKey of the product", 100.2],
                  [1570782851708, "property", "0987654321", "ProductKey of the product", 104.4]
              ]
          }]
      }]
  }

• Query by device to retrieve the values of a property at all points in time. The response lists all stored property values in chronological order.

  curl -G 'http://localhost:8086/query?db=example&u=root&p=root' --data-urlencode "epoch=ms" --data-urlencode 'q=SELECT * FROM "Unique property identifier (unique within the product)" WHERE "_deviceName" = $dn and "_dataType" = $type' --data-urlencode 'params={"dn":"Device name", "type": "property"}'

• Query by device to retrieve the values of a property within a specific time range. The response lists all stored property values within that time range in chronological order.

  curl -G 'http://localhost:8086/query?db=example&u=root&p=root' --data-urlencode "epoch=ms" --data-urlencode 'q=SELECT * FROM "Unique property identifier (unique within the product)" WHERE "_productKey" = $pk and "_dataType" = $type and "time" > $timestamp' --data-urlencode 'params={"pk":"ProductKey of the product", "type": "property", "timestamp": "2019-10-11T09:03:15.611Z"}'

Appendix: Data format definition

The following shows the storage format in InfluxDB for device property data and event-type data.

• Single-value property

  [
      {
        "measurement": "temp",            // Property name
        "tags": {                         // Property tags
          "_productKey": "1234567890",    // ProductKey from the device certificate
          "_deviceName": "0987654321",    // DeviceName from the device certificate
          "_dataType"  : "property"       // Type: property indicates a property, and event indicates an event
        },
        "time": 1346846400000,            // Timestamp in milliseconds
        "fields": {
          "value": 123                    // Property value
        }
      }
      ...
  ]

• Struct property

  [
      {
        "measurement": "temp",            // Property name
        "tags": {                         // Property tags
          "_productKey": "1234567890",    // ProductKey from the device certificate
          "_deviceName": "0987654321",    // DeviceName from the device certificate
          "_dataType"  : "property"       // Type: property indicates a property, and event indicates an event
        },
        "time": 1346846400000,            // Timestamp in milliseconds
        "fields": {
          "aa": 12,                       // Property value
          "bb": 12,                       // Property value
          "cc": 12,                       // Property value
          "dd": 12,                       // Property value
        }
      }
      ...
  ]

• Event

  [
      {
        "measurement": "event123",        // Event name
        "tags": {                         // Event tags
          "_productKey": "1234567890",    // ProductKey from the device certificate
          "_deviceName": "0987654321",    // DeviceName from the device certificate
          "_dataType"  : "event"          // Type: property indicates a property, and event indicates an event
        },
        "time": 1346846400000,            // Timestamp in milliseconds
        "fields": {
          "speed" : 20.8,
          "level" : 4,
          "direction" : "East",
        }
      }
      ...
  ]