removed all panic(err) calls, added meaningful error messages, added checks for returning statuscodes from API

example.json

@@ -1,9 +1,9 @@
 {
-  "timestamp": "2020-12-29T18:46:27+0100",
+  "timestamp": "2020-12-31T12:19:04+0100",
   "nodes": [
     {
       "firstseen": "2020-01-20T17:38:03+0000",
-      "lastseen": "2020-12-29T17:46:00+0000",
+      "lastseen": "2020-12-31T11:18:07+0000",
       "is_online": true,
       "is_gateway": false,
       "clients": 0,
@@ -11,9 +11,9 @@
       "clients_wifi5": 0,
       "clients_other": 0,
       "rootfs_usage": 0,
-      "loadavg": 0.03,
-      "memory_usage": 0.66,
-      "uptime": "2020-11-22T14:02:11+0000",
+      "loadavg": 0.26,
+      "memory_usage": 0.67,
+      "uptime": "2020-11-22T14:02:12+0000",
       "gateway_nexthop": "18e8292f7de6",
       "gateway": "a28cae6ff604",
       "location": {
@@ -41,7 +41,7 @@
     },
     {
       "firstseen": "2020-05-05T20:08:20+0000",
-      "lastseen": "2020-12-29T17:46:08+0000",
+      "lastseen": "2020-12-31T11:18:26+0000",
       "is_online": true,
       "is_gateway": false,
       "clients": 0,
@@ -49,9 +49,9 @@
       "clients_wifi5": 0,
       "clients_other": 0,
       "rootfs_usage": 0,
-      "loadavg": 0.02,
+      "loadavg": 0.25,
       "memory_usage": 0.68,
-      "uptime": "2020-10-24T21:47:31+0000",
+      "uptime": "2020-10-24T21:47:32+0000",
       "gateway_nexthop": "18e8292f7de6",
       "gateway": "a28cae6ff604",
       "location": {
@@ -83,8 +83,8 @@
       "type": "wifi",
       "source": "18e8298ec64d",
       "target": "18e829dcc37e",
-      "source_tq": 0.315,
-      "target_tq": 0.315,
+      "source_tq": 0.345,
+      "target_tq": 0.345,
       "source_addr": "18:e8:29:8e:c6:4d",
       "target_addr": "18:e8:29:dc:c3:7e"
     }

main.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"flag"
+	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
@@ -27,19 +29,27 @@ func main() {
 
 	// check if token is set
 	if *token == "" {
-		log.Println("Please specify an API token via the flag '-token'")
-		os.Exit(1)
+		log.Fatalln("Please specify an API token via the flag '-token'")
 	}
 
+	log.Println("starting...")
+
 	// Variables for runtime
 	var links []link
 	var nodes []node
 
-	d := getDevices()
+	d, err := getDevices()
+	if err != nil {
+		log.Fatalln(err)
+	}
 
 	// API CALL 1
+	log.Println("calling API 1")
 	var u []unifiAPIResponse
-	callUnifiAPI("/devices", &u)
+	err = callUnifiAPI("/devices", &u)
+	if err != nil {
+		log.Fatalln(err)
+	}
 
 	for i := range d.Devices {
 		var dev unifiAPIResponse
@@ -51,26 +61,23 @@ func main() {
 			}
 		}
 
-		// fmt.Println(time.Now().Format(iso8601))
 		var isOnline bool = false
 		if dev.Overview.Status == "active" {
 			isOnline = true
 		}
-
-		// uptime := dev.Identification.Started.Format(iso8601)
-		// nodeID := strings.ReplaceAll(dev.Identification.MAC, ":", "")
 		// END OF API CALL 1
 
 		// API CALL 2
+		log.Println("calling API 2 for device", d.Devices[i].Name)
 		var details unifiAPIDetails
 		callUnifiAPI("/devices/erouters/"+dev.Identification.ID, &details)
 		// END OF API CALL 2
 
 		// API CALL 3
+		log.Println("calling API 3 for device", d.Devices[i].Name)
 		var airmaxes []unifiAPIAirmax
 		callUnifiAPI("/devices/airmaxes/"+dev.Identification.ID+"/stations", &airmaxes)
 		// check if remote mac address is part of our published network
-		// if isRemoteMACpublished()
 		for i := range airmaxes {
 			if isRemoteMACpublished(airmaxes[i].DeviceIdentification.MAC, d.Devices) == true {
 				links = addLink(dev, airmaxes[i], links)
@@ -122,14 +129,18 @@ func main() {
 	}
 
 	// create file output
+	log.Println("writing json file")
 	writeJSONtoFile(o)
+
+	// we're done here
+	log.Println("...done")
 }
 
-func getDevices() devices {
+func getDevices() (devices, error) {
 	// get devices from JSON file
 	jsonFile, err := os.Open("devices.json")
 	if err != nil {
-		panic(err)
+		return devices{}, errors.New("can't open devices.json")
 	}
 	defer jsonFile.Close()
 
@@ -140,28 +151,37 @@ func getDevices() devices {
 	var d devices
 	// unmarshal to struct
 	json.Unmarshal(byteValue, &d)
-	return d
+	return d, nil
 }
 
-func callUnifiAPI(url string, i interface{}) {
+func callUnifiAPI(url string, i interface{}) error {
 	request, err := http.NewRequest(http.MethodGet, baseURL+url, nil)
 	if err != nil {
-		panic(err)
+		return errors.New(fmt.Sprint("can't set request", baseURL+url))
 	}
 	request.Header.Set("x-auth-token", *token)
 	client := &http.Client{}
 	response, err := client.Do(request)
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("can't get request %s with x-auth-token %s", baseURL+url, *token)
 	}
 
 	data, err := ioutil.ReadAll(response.Body)
+	defer response.Body.Close()
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("can't read response body: %+v", response.Body)
 	}
-	// fmt.Println(string(data))
+	// try to fetch errors
+	var a apiResponse
+	json.Unmarshal(data, &a)
 
+	if a.StatusCode != 0 {
+		return fmt.Errorf("got following errorcode from API: %d %s %s", a.StatusCode, a.Error, a.Message)
+	}
+
+	// no error occurred, unmarshal to struct
 	json.Unmarshal(data, &i)
+	return nil
 }
 
 func isRemoteMACpublished(mac string, devices []device) bool {
@@ -192,17 +212,18 @@ func addLink(dev unifiAPIResponse, airmaxes unifiAPIAirmax, links []link) []link
 	return links
 }
 
-func writeJSONtoFile(o output) {
+func writeJSONtoFile(o output) error {
 	file, err := json.MarshalIndent(o, "", "  ")
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("can't marshal to json: %+v", o)
 	}
 
 	// write to file
 	err = ioutil.WriteFile("example.json", file, 0644)
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("can't write to json file example.json")
 	}
+	return nil
 }
 
 func getAddresses(ip string) []string {

types.go

@@ -110,3 +110,9 @@ type output struct {
 	Nodes     []node `json:"nodes"`
 	Links     []link `json:"links"`
 }
+
+type apiResponse struct {
+	StatusCode int    `json:"statusCode"`
+	Error      string `json:"error"`
+	Message    string `json:"message"`
+}