Merge branch '2.2' into 3.0

# Conflicts:
#	.github/workflows/testing.yml
#	CHANGELOG
#	README.md
#	dev-requirements.txt
#	gns3server/compute/docker/docker_vm.py
#	gns3server/controller/export_project.py
#	gns3server/controller/import_project.py
#	gns3server/controller/project.py
#	gns3server/crash_report.py
#	gns3server/static/web-ui/index.html
#	gns3server/static/web-ui/main.df8c319a3da6fb0e3629.js
#	gns3server/version.py
#	requirements.txt
#	setup.py
#	tests/compute/docker/test_docker_vm.py
#	tests/controller/test_import_project.py

gns3server/compute/base_node.py

@@ -742,6 +742,7 @@ class BaseNode:
         path = shutil.which(self._manager.config.settings.Server.ubridge_path)
         return path
 
+    @locking
     async def _ubridge_send(self, command):
         """
         Sends a command to uBridge hypervisor.

gns3server/compute/docker/docker_vm.py

@@ -464,8 +464,8 @@ class DockerVM(BaseNode):
                 "Mounts": self._mount_binds(image_infos),
                 "Memory": self._memory * (1024 * 1024),  # convert memory to bytes
                 "NanoCpus": int(self._cpus * 1e9),  # convert cpus to nano cpus
+                "UsernsMode": "host"
             },
-            "UsernsMode": "host",
             "Volumes": {},
             "Env": ["container=docker"],  # Systemd compliant: https://github.com/GNS3/gns3-server/issues/573
             "Cmd": [],

gns3server/compute/docker/resources/init.sh

@@ -25,7 +25,10 @@ PATH=/gns3/bin:/tmp/gns3/bin:/sbin:$PATH
 # bootstrap busybox commands
 if [ ! -d /tmp/gns3/bin ]; then
 	busybox mkdir -p /tmp/gns3/bin
-	/gns3/bin/busybox --install -s /tmp/gns3/bin
+	for applet in `busybox --list`
+	do
+	  ln -s /gns3/bin/busybox "/tmp/gns3/bin/$applet"
+	done
 fi
 
 #  Restore file permission and mount volumes
@@ -75,7 +78,7 @@ ip link set dev lo up
 while true 
 do
     grep $GNS3_MAX_ETHERNET /proc/net/dev > /dev/null && break
-    sleep 0.5
+    usleep 500000  # wait 0.5 seconds
 done  
 
 # activate eth interfaces