Experimenting with macOS MagicDNS

Signed-off-by: Percy Wegmann <percy@tailscale.com>

Author: oxtoacart

.github/workflows/test.yml

@@ -16,61 +16,69 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          # Linux tests (AMD64)
-          - os: ubuntu-latest
-            runner-os: Linux
+          # # Linux tests (AMD64)
+          # - os: ubuntu-latest
+          #   runner-os: Linux
+          #   arch: amd64
+          #   version: latest
+          #   ping: 100.99.0.2,lax-pve.pineapplefish.ts.net,lax-pve
+
+          # # Try unstable too
+          # - os: ubuntu-latest
+          #   runner-os: Linux
+          #   arch: amd64
+          #   version: unstable
+
+          # # Try a pinned version
+          # - os: ubuntu-latest
+          #   runner-os: Linux
+          #   arch: amd64
+          #   # leave version blank to fall back to default
+
+          # # Linux tests (ARM64)
+          # - os: ubuntu-24.04-arm
+          #   runner-os: Linux
+          #   arch: arm64
+          #   version: latest
+
+          # # Windows tests (AMD64)
+          # - os: windows-latest
+          #   runner-os: Windows
+          #   arch: amd64
+          #   version: latest
+          #   ping: 100.99.0.2,lax-pve.pineapplefish.ts.net,lax-pve
+
+          # - os: windows-latest
+          #   runner-os: Windows
+          #   arch: amd64
+          #   version: unstable
+
+          # # Windows tests (ARM64)
+          # - os: windows-11-arm
+          #   runner-os: Windows
+          #   arch: arm64
+          #   version: latest
+
+          # macOS 13 intel
+          - os: macos-13
+            runner-os: macOS
             arch: amd64
             version: latest
             ping: 100.99.0.2,lax-pve.pineapplefish.ts.net,lax-pve
 
-          # Try unstable too
-          - os: ubuntu-latest
-            runner-os: Linux
-            arch: amd64
-            version: unstable
-
-          # Try a pinned version
-          - os: ubuntu-latest
-            runner-os: Linux
-            arch: amd64
-            # leave version blank to fall back to default
-
-          # Linux tests (ARM64)
-          - os: ubuntu-24.04-arm
-            runner-os: Linux
+          # macOS 14 ARM
+          - os: macos-14
+            runner-os: macOS
             arch: arm64
             version: latest
-
-          # Windows tests (AMD64)
-          - os: windows-latest
-            runner-os: Windows
-            arch: amd64
-            version: latest
             ping: 100.99.0.2,lax-pve.pineapplefish.ts.net,lax-pve
 
-          - os: windows-latest
-            runner-os: Windows
-            arch: amd64
-            version: unstable
-
-          # Windows tests (ARM64)
-          - os: windows-11-arm
-            runner-os: Windows
-            arch: arm64
-            version: latest
-
-          # macOS intel
-          - os: macos-13
-            runner-os: macOS
-            arch: amd64
-            version: latest
-            ping: 100.99.0.2 # hostnames aren't resolving on MacOS, just ping IP lax-pve.pineapplefish.ts.net,lax-pve
-
-          # macOS ARM
-          - os: macos-14
+          # macOS 15 ARM
+          - os: macos-15
             runner-os: macOS
             arch: arm64
             version: latest
+            ping: 100.99.0.2,lax-pve.pineapplefish.ts.net,lax-pve
 
     runs-on: ${{ matrix.os }}
 
@@ -83,7 +91,7 @@ jobs:
         with:
           node-version: "24"
           cache: "npm"
-
+      
       - name: Install Dependencies
         run: npm ci
 

dist/index.js

@@ -41232,6 +41232,8 @@ async function run() {
         config.arch = getTailscaleArch(runnerOS);
         // Install Tailscale
         await installTailscale(config, runnerOS);
+        // Set DNS server to quad 100 if necessary
+        await setDNSServerIfNecessary(runnerOS);
         // Start daemon (non-Windows only)
         if (runnerOS !== runnerWindows) {
             await startTailscaleDaemon(config);
@@ -41750,6 +41752,22 @@ async function installCachedBinaries(toolPath, runnerOS) {
         }
     }
 }
+async function setDNSServerIfNecessary(runnerOS) {
+    if (runnerOS !== runnerMacOS) {
+        return;
+    }
+    core.info("Setting system DNS server to 100.100.100.100");
+    try {
+        await exec.exec("networksetup", [
+            "-setdnsservers",
+            "Ethernet",
+            "100.100.100.100",
+        ]);
+    }
+    catch (e) {
+        core.warning(`Failed to set DNS server to 100.100.100.100, continuing: ${e}`);
+    }
+}
 run();
 
 

src/main.ts

@@ -157,6 +157,9 @@ async function run(): Promise<void> {
     // Install Tailscale
     await installTailscale(config, runnerOS);
 
+    // Set DNS server to quad 100 if necessary
+    await setDNSServerIfNecessary(runnerOS);
+
     // Start daemon (non-Windows only)
     if (runnerOS !== runnerWindows) {
       await startTailscaleDaemon(config);
@@ -799,4 +802,23 @@ async function installCachedBinaries(
   }
 }
 
+async function setDNSServerIfNecessary(runnerOS: string): Promise<void> {
+  if (runnerOS !== runnerMacOS) {
+    return;
+  }
+
+  core.info("Setting system DNS server to 100.100.100.100");
+  try {
+    await exec.exec("networksetup", [
+      "-setdnsservers",
+      "Ethernet",
+      "100.100.100.100",
+    ]);
+  } catch (e) {
+    core.warning(
+      `Failed to set DNS server to 100.100.100.100, continuing: ${e}`
+    );
+  }
+}
+
 run();