[xdl] Start Ngrok only when running expo start --tunnel (#2088)

* [xdl]  Start Ngrok only when running expo start --tunnel

Fixes #335

* this doesn't actually return packagerOpts, so destructure instead of using incorrect name

* [dev-tools] toggling 'tunnel' in DevTools should start tunnels

* Update packages/dev-tools/server/graphql/GraphQLSchema.ts

Co-authored-by: Ville Immonen <ville.immonen@iki.fi>

Co-authored-by: Ville Immonen <ville.immonen@iki.fi>

packages/dev-tools/server/graphql/GraphQLSchema.ts

@@ -576,7 +576,22 @@ const resolvers = {
     },
     async setProjectSettings(parent, { settings }, context) {
       const currentProject = context.getCurrentProject();
+      let previousSettings = await ProjectSettings.readAsync(currentProject.projectDir);
       let updatedSettings = await ProjectSettings.setAsync(currentProject.projectDir, settings);
+
+      // If 'tunnel' wasn't previously configured and it will be as a result of this request, start tunnels.
+      if (previousSettings.hostType !== 'tunnel' && updatedSettings.hostType === 'tunnel') {
+        try {
+          await Project.startTunnelsAsync(currentProject.projectDir);
+        } catch (e) {
+          ProjectUtils.logWarning(
+            currentProject.projectDir,
+            'expo',
+            `Error starting tunnel ${e.message}`
+          );
+        }
+      }
+
       return {
         ...currentProject,
         settings: updatedSettings,

packages/xdl/src/Project.ts

@@ -2399,7 +2399,9 @@ export async function startAsync(
     DevSession.startSession(projectRoot, exp, 'native');
   }
 
-  if (!Config.offline) {
+  const { hostType } = await ProjectSettings.readAsync(projectRoot);
+
+  if (!Config.offline && hostType === 'tunnel') {
     try {
       await startTunnelsAsync(projectRoot);
     } catch (e) {