Fixed update checker making requests to uptime.kuma.pet even when turned off (#2281)

* fix: update checker

- fixed bug where it would make the request to uptime.kuma.pet regardless of the `checkUpdate` config;
- defined constants in the top of the document for easier configuration/documentation;
- removed unnecessary compareVersions: we were comparing the same var on both sides res.data.beta, so it will always be equal.

* improvement: better logging and added doc

* improved UPDATE_CHECKER_INTERVAL_MS const

---------

Co-authored-by: Louis Lam <louislam@users.noreply.github.com>

server/check-version.js

@@ -1,27 +1,33 @@
 const { setSetting, setting } = require("./util-server");
 const axios = require("axios");
 const compareVersions = require("compare-versions");
+const { log } = require("../src/util");
 
 exports.version = require("../package.json").version;
 exports.latestVersion = null;
 
+// How much time in ms to wait between update checks
+const UPDATE_CHECKER_INTERVAL_MS = 1000 * 60 * 60 * 48;
+const UPDATE_CHECKER_LATEST_VERSION_URL = "https://uptime.kuma.pet/version";
+
 let interval;
 
-/** Start 48 hour check interval */
 exports.startInterval = () => {
     let check = async () => {
+        if (await setting("checkUpdate") === false) {
+            return;
+        }
+
+        log.debug("update-checker", "Retrieving latest versions");
+
         try {
-            const res = await axios.get("https://uptime.kuma.pet/version");
+            const res = await axios.get(UPDATE_CHECKER_LATEST_VERSION_URL);
 
             // For debug
             if (process.env.TEST_CHECK_VERSION === "1") {
                 res.data.slow = "1000.0.0";
             }
 
-            if (await setting("checkUpdate") === false) {
-                return;
-            }
-
             let checkBeta = await setting("checkBeta");
 
             if (checkBeta && res.data.beta) {
@@ -35,12 +41,14 @@ exports.startInterval = () => {
                 exports.latestVersion = res.data.slow;
             }
 
-        } catch (_) { }
+        } catch (_) {
+            log.info("update-checker", "Failed to check for new versions");
+        }
 
     };
 
     check();
-    interval = setInterval(check, 3600 * 1000 * 48);
+    interval = setInterval(check, UPDATE_CHECKER_INTERVAL_MS);
 };
 
 /**