#!/bin/bash
set -e

echo "=== Cleaning up old containers ==="
docker rm -f bridge-demo host-demo 2>/dev/null || true

echo "=== Starting container in default bridge network ==="
docker run -d --name bridge-demo --rm alpine sleep 300

echo "=== Starting container in host network ==="
docker run -d --name host-demo --network host --rm alpine sleep 300

echo
echo "=== Showing Docker bridge (docker0) info ==="
ip addr show docker0
brctl show docker0 || true

echo
echo "=== Finding network namespace of bridge-demo container ==="
BRIDGE_PID=$(docker inspect -f '{{.State.Pid}}' bridge-demo)
echo "bridge-demo PID: $BRIDGE_PID"
ls -l /proc/$BRIDGE_PID/ns/net

echo
echo "=== Interfaces inside bridge-demo namespace ==="
nsenter --net=/proc/$BRIDGE_PID/ns/net ip addr

echo
echo "=== veth pair mapping for bridge-demo ==="
# The host-side veth will have a name like vethXXXX
HOST_VETH=$(ip link | grep -B1 "@if" | grep veth | awk '{print $2}' | tr -d :)
echo "Host veth: $HOST_VETH"

echo
echo "=== Network namespace of host-demo container ==="
HOST_PID=$(docker inspect -f '{{.State.Pid}}' host-demo)
echo "host-demo PID: $HOST_PID"
ls -l /proc/$HOST_PID/ns/net

echo
echo "=== Interfaces inside host-demo namespace (same as host) ==="
nsenter --net=/proc/$HOST_PID/ns/net ip addr

echo
echo "=== Routing table for bridge-demo ==="
nsenter --net=/proc/$BRIDGE_PID/ns/net ip route

echo
echo "=== Routing table for host-demo ==="
nsenter --net=/proc/$HOST_PID/ns/net ip route

echo
echo "=== Cleanup ==="
#docker rm -f bridge-demo host-demo