export database: fix async logic

src/addons.js

@@ -782,11 +782,18 @@ function exportDatabase(addon, callback) {
                     return iteratorCallback(error);
                 }
 
-                safe.fs.writeFileSync(path.join(paths.ADDON_CONFIG_DIR, `exported-${addon}`), '', 'utf8');
-
-                shell.sudo('exportDatabase', [ RMADDONDIR_CMD, addon ], {}, iteratorCallback);
+                iteratorCallback();
             });
-        }, callback);
+        }, function (error) {
+            if (error) return callback(error);
+
+            async.series([
+                (done) => fs.writeFile(path.join(paths.ADDON_CONFIG_DIR, `exported-${addon}`), '', 'utf8', done),
+                // note: after this point, we are restart safe. it's ok if the box code crashes at this point
+                (done) => shell.exec(`exportDatabase - remove${addon}`, `docker rm -f ${addon}`, done), // what if db writes something when quitting ...
+                (done) => shell.sudo(`exportDatabase - removeAddonDir${addon}`, [ RMADDONDIR_CMD, addon ], {}, done) // ready to start afresh
+            ], callback);
+        });
     });
 }
 
@@ -1790,7 +1797,7 @@ function startRedis(existingInfra, callback) {
             const redisName = 'redis-' + app.id;
 
             async.series([
-                shell.exec.bind(null, 'stopRedis', `docker stop ${redisName} || true`),
+                shell.exec.bind(null, 'stopRedis', `docker stop ${redisName} || true`), // redis will backup as part of signal handling
                 shell.exec.bind(null, 'removeRedis', `docker rm -f ${redisName} || true`),
                 setupRedis.bind(null, app, app.manifest.addons.redis) // starts the container
             ], iteratorCallback);