api: add version checking

api/constants.go

@@ -0,0 +1,4 @@
+package main
+
+var edition = "ce"
+var version = "v1.0.0"

api/main.go

@@ -10,6 +10,7 @@ func main() {
 	exitIfError(oauthConfigure())
 	exitIfError(markdownRendererCreate())
 	exitIfError(sigintCleanupSetup())
+	exitIfError(versionCheckStart())
 
 	exitIfError(routesServe())
 }

api/version.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+)
+
+func versionCheckStart() error {
+	go func() {
+		printedError := false
+		errorCount := 0
+
+		for {
+			time.Sleep(5 * time.Minute)
+
+			data := url.Values{
+				"origin":  {os.Getenv("ORIGIN")},
+				"edition": {edition},
+				"version": {version},
+			}
+
+			resp, err := http.Post("https://version.commento.io/api/check", "application/x-www-form-urlencoded", bytes.NewBufferString(data.Encode()))
+			if err != nil {
+				errorCount++
+				// print the error only once; we don't want to spam the logs with this
+				// every five minutes
+				if !printedError && errorCount > 5 {
+					logger.Errorf("error checking version: %v", err)
+					printedError = true
+				}
+				continue
+			}
+			defer resp.Body.Close()
+
+			body, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				errorCount++
+				if !printedError && errorCount > 5 {
+					logger.Errorf("error reading body: %s", err)
+					printedError = true
+				}
+				continue
+			}
+
+			type response struct {
+				Success   bool   `json:"success"`
+				Message   string `json:"message"`
+				Latest    string `json:"latest"`
+				NewUpdate bool   `json:"newUpdate"`
+			}
+
+			r := response{}
+			json.Unmarshal(body, &r)
+			if r.Success == false {
+				errorCount++
+				if !printedError && errorCount > 5 {
+					logger.Errorf("error checking version: %s", r.Message)
+					printedError = true
+				}
+				continue
+			}
+
+			if r.NewUpdate {
+				logger.Infof("New update available! Latest version: %s", r.Latest)
+			}
+
+			errorCount = 0
+			printedError = false
+		}
+	}()
+
+	return nil
+}