#888 Fix IP address for Docker (#889)

When this package's nodes run in a Docker container, the get_host_ip
function can return the wrong IP address, causing routing failures.
Now the function checks if the process is running in a Docker
container, returning the special host.docker.internal DNS name.

Signed-off-by: Adam Morrissett <[email protected]>

webots_ros2_driver/scripts/webots_tcp_client.py

@@ -16,14 +16,23 @@
 
 """TCP client to start Webots on the host."""
 
+from pathlib import Path
 import os
 import socket
 import subprocess
 import sys
 import time
 
 
+def is_docker():
+    mountinfo = Path("/proc/self/mountinfo")
+    return mountinfo.is_file() and "docker" in mountinfo.read_text()
+
+
 def get_host_ip():
+    if is_docker():
+        return "host.docker.internal"
+
     try:
         output = subprocess.run(['ip', 'route'], check=True, stdout=subprocess.PIPE, universal_newlines=True)
         for line in output.stdout.split('\n'):

webots_ros2_driver/webots_ros2_driver/utils.py

@@ -123,7 +123,15 @@ def container_shared_folder():
     return shared_folder_list[1]
 
 
+def is_docker():
+    mountinfo = Path("/proc/self/mountinfo")
+    return mountinfo.is_file() and "docker" in mountinfo.read_text()
+
+
 def get_host_ip():
+    if is_docker():
+        return "host.docker.internal"
+
     try:
         output = subprocess.run(['ip', 'route'], check=True, stdout=subprocess.PIPE, universal_newlines=True)
         for line in output.stdout.split('\n'):