Temporary fix for macOS runner upgrade crash loop. (actions#1304)

src/Misc/layoutbin/update.sh.template

@@ -118,6 +118,43 @@ then
     exit 1
 fi
 
+# fix upgrade issue with macOS
+currentplatform=$(uname | awk '{print tolower($0)}')
+if [[ "$currentplatform" == 'darwin' ]]; then
+    # need a short-term fix for https://github.com/actions/runner/issues/743
+    # we will recreate all the ./externals/node12/bin/node of the past 5 versions
+    # v2.280.3 v2.280.2 v2.280.1 v2.279.0 v2.278.0
+    if [[ ! -e "$rootfolder/externals.2.280.3/node12/bin/node" ]]
+    then
+        mkdir -p "$rootfolder/externals.2.280.3/node12/bin"
+        cp "$rootfolder/externals/node12/bin/node" "$rootfolder/externals.2.280.3/node12/bin/node"
+    fi
+
+    if [[ ! -e "$rootfolder/externals.2.280.2/node12/bin/node" ]]
+    then
+        mkdir -p "$rootfolder/externals.2.280.2/node12/bin"
+        cp "$rootfolder/externals/node12/bin/node" "$rootfolder/externals.2.280.2/node12/bin/node"
+    fi
+
+    if [[ ! -e "$rootfolder/externals.2.280.1/node12/bin/node" ]]
+    then
+        mkdir -p "$rootfolder/externals.2.280.1/node12/bin"
+        cp "$rootfolder/externals/node12/bin/node" "$rootfolder/externals.2.280.1/node12/bin/node"
+    fi
+
+    if [[ ! -e "$rootfolder/externals.2.279.0/node12/bin/node" ]]
+    then
+        mkdir -p "$rootfolder/externals.2.279.0/node12/bin"
+        cp "$rootfolder/externals/node12/bin/node" "$rootfolder/externals.2.279.0/node12/bin/node"
+    fi
+
+    if [[ ! -e "$rootfolder/externals.2.278.0/node12/bin/node" ]]
+    then
+        mkdir -p "$rootfolder/externals.2.278.0/node12/bin"
+        cp "$rootfolder/externals/node12/bin/node" "$rootfolder/externals.2.278.0/node12/bin/node"
+    fi
+fi
+
 date "+[%F %T-%4N] Update succeed" >> "$logfile"
 
 # rename the update log file with %logfile%.succeed/.failed/succeedneedrestart

src/Runner.Listener/SelfUpdater.cs

@@ -74,10 +74,12 @@ public async Task<bool> SelfUpdate(AgentRefreshMessage updateMessage, IJobDispat
                 await jobDispatcher.WaitAsync(token);
                 Trace.Info($"All running job has exited.");
 
+                // We need to keep runner backup around for macOS until we fixed https://github.com/actions/runner/issues/743
+#if !OS_OSX
                 // delete runner backup
                 DeletePreviousVersionRunnerBackup(token);
                 Trace.Info($"Delete old version runner backup.");
-
+#endif
                 // generate update script from template
                 await UpdateRunnerUpdateStateAsync("Generate and execute update script.");