Docker Container Launch hangs with Docker Engine 29+ — top-level NetworkSettings.IPAddress removed

[rotassoftware]

yes, the issue is AI generated, i already used 4h of my life battling it.

Environment

• Eclipse CDT 2026-03 (4.39.0)
• Eclipse Docker Tooling 5.22.0
• org.eclipse.cdt.docker.launcher 2.1.700
• org.mandas.docker-client 10.0.0
• Docker Engine 29.5.0 (API 1.52)
• Linux (Ubuntu 24.04)

Problem

The "C/C++ Docker Container Launch" debug configuration hangs indefinitely after gdbserver starts in the container. GDB is never launched on the host.

Root Cause

ContainerLaunchConfigurationDelegate$StartGdbServerJob.getIpAddress() reads the container IP from IDockerContainerInfo.networkSettings().ipAddress(), which maps to the top-level NetworkSettings.IPAddress field in Docker's inspect response.

Docker Engine 29.0.0 removed this field (deprecated since Docker 1.13 via moby/moby#28437, removed in moby/moby#50846). The IP address is now only available in NetworkSettings.Networks.<network_name>.IPAddress.

Since the top-level field returns null, the StartGdbServerJob polling loop never terminates, and GDB is never started.

Reproduction

1. Install Docker Engine 29+
2. Create a C/C++ Docker Container Launch debug config
3. Launch debug → gdbserver starts, output shows "Listening on port 2345"
4. Eclipse hangs forever — no GDB process is started

Verification

# Docker 29 returns null for top-level IPAddress:
docker run -d --rm --name test alpine sleep 60
docker inspect test | python3 -c "
import json,sys
ns=json.load(sys.stdin)[0]['NetworkSettings']
print('Top-level:', repr(ns.get('IPAddress')))      # None
print('Networks.bridge:', repr(ns['Networks']['bridge']['IPAddress']))  # '172.17.0.2'
"
docker rm -f test

Suggested Fix

In DockerNetworkSettings, fallback to Networks map when ipAddress() is null:

public String ipAddress() {
    if (this.ipAddress != null && !this.ipAddress.isEmpty()) {
        return this.ipAddress;
    }
    // Fallback for Docker Engine 29+ where top-level field was removed
    if (this.networks != null) {
        for (var entry : this.networks.entrySet()) {
            String ip = entry.getValue().ipAddress();
            if (ip != null && !ip.isEmpty()) {
                return ip;
            }
        }
    }
    return this.ipAddress;
}

Workaround

Use a Unix socket proxy that forces API version 1.43, which makes Docker return the legacy format with the top-level IPAddress field populated:

# Proxy rewrites requests to /v1.43/... forcing Docker to respond with legacy format
# Listen on /var/run/docker-eclipse.sock, forward to /var/run/docker.sock
# Then configure Eclipse Docker connection to use the proxy socket

Related

• moby/moby#28437 — deprecate top-level network info (Docker 1.13, 2016)
• moby/moby#50846 — remove NetworkSettingsBase and DefaultNetworkSettings (Docker 29.0.0)
• moby/moby#50848 — deprecate NetworkSettingsBase.Bridge and DefaultNetworkSettings fields