warning on old version

Author: gauron99

.github/workflows/test-action.yml

@@ -16,7 +16,7 @@ jobs:
   test-custom-version:
     runs-on: ubuntu-latest
     env:
-      TEST_VERSION: '1.19.0'
+      TEST_VERSION: '1.18.0'
       VERSION_OFFSET: 27  # internal version = minor + offset (v1.19 → v0.46)
     steps:
       - uses: actions/checkout@v4

index.js

@@ -88,6 +88,48 @@ function resolveUrl(version, bin) {
     return `${base}/${last}`;
 }
 
+// Returns difference of minor versions between 'latest' and 'version'
+// subtracts 'version' from 'latest' (returns negative if 'version' is ahead)
+// If minor version cannot be extracted on either number - return 0
+function versionDiff(latest, version) {
+    const extractMinor = (v) => {
+        const match = v.match(/(\d+)\.(\d+)/);
+        return match ? parseInt(match[2], 10) : null;
+    };
+
+    const latestMinor = extractMinor(latest);
+    const versionMinor = extractMinor(version);
+    if (latestMinor === null || versionMinor === null) {
+        return 0;
+    }
+    return latestMinor - versionMinor;
+}
+
+// Warn if version requested is more than 2 versions behind latest (>= 3)
+// This function does NOT error
+async function warnStaleVersion(version) {
+    const API_LATEST = 'https://api.github.com/repos/knative/func/releases/latest';
+    const THRESHOLD = 3;
+
+    try {
+        const response = await fetch(API_LATEST);
+        if (!response.ok) {
+            throw new Error(`failed to fetch latest version: ${response.status}`);
+        }
+
+        const data = await response.json();
+        const latest = data.tag_name;
+        const diff = versionDiff(latest, version);
+        if (diff >= THRESHOLD) {
+            core.warning(
+                `You are using func ${version}, which is ${diff} versions behind the latest (${latest}). Upgrading is recommended.`
+            );
+        }
+    } catch (error) {
+        core.debug(`Skipping stale version check: ${error.message}`);
+    }
+}
+
 async function run() {
     const osBinName = core.getInput('binary') || getOsBinName();
     if (osBinName === "unknown") {
@@ -104,17 +146,20 @@ async function run() {
     }
 
     let url;
+    let version = '';
+
     if (binarySourceInput) {
+        // Custom binarySource - full URL, skip version check
         core.info(`Using custom binary source: ${binarySourceInput}`);
         url = binarySourceInput;
     } else if (versionInput.toLowerCase().trim() === 'latest') {
-        // use latest version
+        // Latest version
         core.info("Using latest version...");
         url = resolveUrl('latest', osBinName);
     } else {
-        // try smart version update
+        // Specific version
         try {
-            const version = smartVersionUpdate(versionInput);
+            version = smartVersionUpdate(versionInput);
             url = resolveUrl(version, osBinName);
         } catch (error) {
             core.setFailed(error.message);
@@ -134,6 +179,11 @@ async function run() {
         return;
     }
 
+    // Warn if using an old version (only for specific versions, not binarySource or latest)
+    if (version) {
+        await warnStaleVersion(version);
+    }
+
     await addBinToPath(fullPathBin);
     await exec.exec(fullPathBin, ['version']);
 }