Looking for example in go-lang for binding the Influx-Db

[StreetCruiser]

Hello everybody.

Just wondering if someone knows any link (or article) how to bind the Influx DB in go-lang in the ctrlX Core environment?

The article I found is using the NodeRed and Telegraf Apps:

https://developer.community.boschrexroth.com/t5/Store-and-How-to/Getting-started-with-InfluxDB-on-ct...

Required is direct binding of the database in the go-lang and App-Builder-Environment for ctrlX Core.

In www there are some examples how to use the Influx DB with go-lang, but the examples don't work in ctrlX Core environment - I guess because of some restriction (firewall?) in port and so on, as well as some unmatched environment variable in Ubuntu.

Any information is highly appreciated. Thanks.

[nickH]

Hi StreetCruiser, 

I found the InfluxDB Client Api for Go online at docs.influxdata.com: here. 

Can you tell us a little bit more about, what are you trying to do:

• Does your InfluxDB Client run also on the ctrlX CORE or does it run outside?
• Do you use the ctrlX COREvirtual to test it or the real ctrlX CORE?
• Which version of the InfluxDB App do you use?
• Do you use the right token, do you use the right url?
• What do you mean with don't work, can you give a error message or something? 

Best regards, 
Nick

[nickH]

I also just found the general Rest-Api of InfluxDB here. You could also send http requests from your go application. 

Additional hint: Influx recommends to use popular tools like postman to test the api.

[StreetCruiser]

Hi Nick.

Thank you so much for your prompt reply. As for your questions:

• Does your InfluxDB Client run also on the ctrlX CORE or does it run outside?

    It shall run in the ctrlX CORE or ctrlX Virtual, respectively.

• Do you use the ctrlX COREvirtual to test it or the real ctrlX CORE?

    I am using both of them - virtual for creating the program, core for smoke testing.

• Which version of the InfluxDB App do you use?

    InfluxDB v2.4.0

• Do you use the right token, do you use the right url?

    I followed the instruction in the "Get Started" within the app installed for ctrlX Core for programming with go (see attached screenshot).

• What do you mean with don't work, can you give a error message or something?

    I try to go run main.go in the Visual Studio Code (main.go copied from "Get Started") - it exits immediately with the code 1 (see screenshot attached as well).

I guess the code from "Get Started" must be running outside ctrlX Core - it appears strongly to me like a standard example from the manufacturer of InfluxDB.

Any hints what I can do or modify in the standard code to get it run within ctrlX Core environment?

Your help is greatly appreciated. Thanks.

[nickH]

I got some hints for you, because you are trying to connect from a port forwarded App Build Environment to the InfluxDB on a port forwarded ctrlX COREvirtual. Therefore you need to configure some things:

1. You have to forward the port 8086 from your ctrlX COREvirtual to your host system. In the ctrlX WORKS settings:

2. From your go code, running in the App Build Environment you can now make a connection to the influxdb using this url: "http://10.0.2.2:8086". With the ip 10.0.2.2 you can get from the port forwarded App Build Environment back to the localhost of your Host-PC. 

Because you get the message: "unauthorized" I would also check the Token you are using. 

Best regards, 

Nick 

[CodeShepherd]

See also the how to "Communicate between a ctrlX COREvirtual and other applications" for information about general communication.

[StreetCruiser]

Hello there.

Unfortunately I didn't get the example in "Get Started" running - somehow I must have missed some correct settings.

Well forget to mention I am absolutely a beginner in Linux/Ubuntu world and ctrlX App Builder environment; coming from classical, "old" Windows world.

Inbetween I have created an own token and forwarded the port 8086 and create the standard basic project in Visual Studio Code (see attached screenshot).

When debugging, I get the message "context deadline exceeded (Client.Timeout exceeded while awaiting headers)".

I guess I am missing quite a lot of things - does somebody know if there is a SDK-like example out there for binding the Influx DB in the ctrlX Core? A very simple example that is capable to run within App Builder for ctrlX Core?  I assume strongly I am missing the right configuration (port forwarding, token, ... and any other prerequisites...). As aforementioned, I am a beginner in Ubuntu/ctrlX Core and may need quite a help in everything  😄

Is there any step-by-step guide how to do it correctly?

[nickH]

Hi, 

I just tested it and got it to run with a little go-programm. 

First I did the port forwarding for the virtual ctrlX CORE, which I mentioned in a post above. Then I installed the InfluxDB App on my ctrlX CORE virtual (V1.20). I created a Organisation and a Bucket in the influxDB. Then I created a api-token and copied it out. 

I used the influxdb-client-go from github in my App Build Environment. See this code. First I write a value to influx, then I do a quirie on this: 

package main

import (
	"context"
	"fmt"
	"time"
	influxdb2 "github.com/influxdata/influxdb-client-go/v2"
)

const (
	//please insert your organisation, token and bucket here (do the settings prior in influxdb webinterface)
	myToken  = "xxxxxxxxx..." //create a token in influx and paste it in here
	myOrg    = "Boschrexroth" // your organisation name (setting in influxDB)
	myBucket = "TestBucket" // your bucket name (setting in influxDB)
)

func main() {
	// Create a new client using an InfluxDB server base URL and an authentication token
	InfluxDBclient := influxdb2.NewClient("http://10.0.2.2:8086", myToken)

	// write to disired organisation an bucket
	writeAPI := InfluxDBclient.WriteAPIBlocking(myOrg, myBucket)


	// Create a point in influx
	p := influxdb2.NewPointWithMeasurement("metric").
		//AddTag("unit", "temperature").
		AddField("sampleValue", 40.2).
		SetTime(time.Now())
	writeAPI.WritePoint(context.Background(), p)


	// Get query client
	queryAPI := InfluxDBclient.QueryAPI(myOrg)
	// Get parser flux query result
	result, err := queryAPI.Query(context.Background(), `from(bucket:"TestBucket")|> range(start: -1h) |> filter(fn: (r) => r._measurement == "metric")`)
	if err == nil {
			fmt.Printf("row: %s\n", result.Record().String())
	}

	// Ensures background processes finishes
	InfluxDBclient.Close()
}

[StreetCruiser]

Many thanks for your example. Appreciate it very much!

I will try it and hopefully get a little success.

[StreetCruiser]

Hi nickH.

Thanks to your help, I managed somehow to get the example code given by you in the ctrlX Virtual. After modding the code (token, org and bucket) I can see the value 40.2 in the Data Explorer of influxdb, as well as the _measurement and _field properties (see attachment 2023-05-26_11h28_04.png).

BUT:

The code in the following line produced an error:

fmt.Printf("row: %s\n", result.Record().String())

I modded the line in order to see the reason and I could chase that result.Record() seemed to return nil.

Here is my modded line:

...

func PrintlnEx(strText string) {

    tm := time.Now()

    fmt.Printf(fmt.Sprintf("%.4d-%.2d-%.2d %.2d:%.2d:%.2d.%.3d: %s\r\n", tm.Year(), tm.Month(), tm.Day(), tm.Hour(), tm.Minute(), tm.Second(), tm.Nanosecond()/1000000, strText))

}

...

    // Get parser flux query result

    PrintlnEx("  Querying...")

    result, err := queryAPI.Query(context.Background(), `from(bucket:"bucketHdWin")|> range(start: -1h) |> filter(fn: (r) => r._measurement == "metric")`)

    PrintlnEx("  Querying accomplished.")

    if err == nil {

        if result.Record() != nil {

            PrintlnEx(fmt.Sprintf( "    row: %s", result.Record().String() )  )

        } else {

            PrintlnEx("    ERROR: result.Record() returned nil!")     // <-- The runtime landed here.

        }

    } else {

        PrintlnEx(fmt.Sprintf("    ERROR: %s", err.Error()))

    }

    // Ensures background processes finishes

    PrintlnEx("  Closing DB...")

    InfluxDBclient.Close()

    PrintlnEx("  Closing DB accomplished.")

And I could see in the trace output that the result.Record() obviously returned nil (see attachment 2023-05-26_11h34_01.png).

Any hints what could be wrong?

Thanks in advance.

[nickH · Accepted solution]

Hi @StreetCruiser, 

I'm happy that you managed to write to the influxDB. 🙂

I looked at the influxdb go client on GitHub a little bit deeper. I found the solution for your problem in the section queries (link). 

You can use result.Next() to iterate over the query response. 

result, err := queryAPI.Query(context.Background(), `from(bucket: "TestBucket") |> range(start: -1h) |> filter(fn: (r) => r["_measurement"] == "metric") |> filter(fn: (r) => r["_field"] == "sampleValue")`)
if err == nil {
	// next() to iterate over query result lines
	for result.Next() {
		// print out result
		fmt.Printf("row: %s\n", result.Record().String())
	}
	if result.Err() != nil {
		fmt.Printf("Query error: %s\n", result.Err().Error())
	}

Note: you may have to modify the query for your need. 

Best regards, 

Nick