go-prtg-sensor-api

API for writing PRTG custom sensors in Go.

Example EXE Sensor

This simple example sensor sends an HTTP request to http://paessler.com and returns two channels:

• Response time - time it takes to perform the request and read the body
• Bytes read - number of bytes the body contained

package main

import (
    "fmt"
    "io"
    "log"
    "net/http"
    "time"

    "github.com/PRTG/go-prtg-sensor-api"
)

func main() {
    // Initiate Sensor instance
    sensor := prtg.New()

    // Log start time
    start := time.Now()
    // Perform HTTP request
    resp, err := http.Get("http://paessler.com")
    if err != nil {
        sensor.SetError(true)
        sensor.SetSensorText(err.Error())
        json, err := sensor.MarshalToString()
        if err != nil {
            log.Fatal(err)
        }
        fmt.Println(json)
        return
    }
    // Read the response
    buffer, err := io.ReadAll(resp.Body)
    if err != nil {
        sensor.SetError(true)
        sensor.SetSensorText(err.Error())
        json, err := sensor.MarshalToString()
        if err != nil {
            log.Fatal(err)
        }
        fmt.Println(json)
        return
    }
    // Evaluate results
    responseTime := time.Since(start)
    responseBytes := len(buffer)

    // Response time channel
    sensor.AddChannel("Response time").SetValue(responseTime.Seconds() * 1000).SetUnit(prtg.TimeResponse)
    // Bytes read channel
    sensor.AddChannel("Bytes read").SetValue(responseBytes).SetUnit(prtg.BytesFile)

    json, err := sensor.MarshalToString()
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(json)
}

To test this example in your PRTG installation follow these steps:

1. Build the example
2. Copy the .exe file to [PRTG install folder]\Custom Sensors\EXEXML
3. Go to PRTG web interface
4. Add Sensor to a device of your choice
5. Choose EXE/SCRIPT ADVANCED as sensor typee (filter for Custom Sensors)
6. Under EXE/Script choose the .exe you copied in step 2
7. Done

Example HTTP Data Advanced Sensor

This example sensor uses a http server to serve the sensor data, that can be pulled by a http data advanced sensor.

• Some value - shows sample percentage value
• Something - shows if the Something service is up and running

The Sensor returns an error if "Something" is not ok.

package main

import (
    "fmt"
    "log"
    "math/rand"
    "net/http"

    "github.com/PRTG/go-prtg-sensor-api"
)

func main() {
    // Create a webserver listening on "/"
    http.HandleFunc("/", reportStatus)
    http.ListenAndServe(":8080", nil)
}

func reportStatus(w http.ResponseWriter, r *http.Request) {
    // Initiate PRTG instance
    sensor := prtg.New()

    // Set sensor text
    sensor.SetSensorText("This is a test sensor")

    // Add a channel with a random float value in Percent
    sensor.AddChannel("Some value").SetValue(rand.Float64() * 100).
        SetUnit(prtg.Percent).SetMaxWarnLimit(80).SetMaxErrLimit(90)

    // Take a look if Something is working
    isUp, err := isSomethingUp()
    // Create a Sensor that shows the uptime of Something
    sensor.AddChannel("Something").SetValue(isUp).
        SetValueLookup("prtg.standardlookups.connectionstate.stateonlineok")
    // Create error message on sensor if the Something is down
    if err != nil {
        sensor.SetError(true)
        sensor.SetSensorText("Test sensor error: " + err.Error())
    }

    // Create json output
    json, err := sensor.MarshalToString()
    if err != nil {
        log.Fatal(err)
    }

    // Deliver to website
    _, err = fmt.Fprint(w, json)
    if err != nil {
        log.Fatal(err)
    }
}

func isSomethingUp() (bool, error) {
    // Generate a "Thing" to watch, that is working in 90% of the time
    if rand.Intn(10) > 1 {
        return true, nil
    }
    return false, fmt.Errorf("the Something is struggling")
}

To test this example in your PRTG installation follow these steps:

1. Build the example
2. Run the binary
3. Go to PRTG web interface
4. Add Sensor to a device of your choice
5. Choose HTTP Data Advanced as sensor type
6. Under URL choose the ip of your device with the port 8080
7. Done

Documentation

• PRTG Manual