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Area

dist/quarkus

Describe the bug

Since Keycloak 26.4.0 (after #39924), running Keycloak in Docker with remote debugging enabled fails when using host binding in DEBUG_PORT (e.g., :8787 or :5005).

In 26.3.5, the same setup worked as expected.

Version

26.4.0

Regression

[x] The issue is a regression

Expected behavior

Keycloak should start successfully with DEBUG_PORT="*:5005" and the debugger should be listening on the specified port.

Actual behavior

In 26.4.0, Keycloak fails to start with the following error when using host binding in DEBUG_PORT:

ERROR: transport error 202: getaddrinfo: failed to parse address
ERROR: JDWP Transport dt_socket failed to initialize, TRANSPORT_INIT(510)
JDWP exit error AGENT_ERROR_TRANSPORT_INIT(197): No transports initialized [src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c:700]

✅ Works with DEBUG_PORT=5005 (just the port number, no host binding).
✅ Works with only DEBUG: "true" (no DEBUG_PORT), which binds to the default port 8787.
❌ Fails with DEBUG_PORT="*:5005".

How to Reproduce?

1. Create a docker-compose.yml using Keycloak 26.4.0 with debugging enabled:

services:
  keycloak-26-4-0:

image: quay.io/keycloak/keycloak:26.4.0
container_name: keycloak-26-4-0
ports:

• "8080:8080"
• "5005:5005"
  environment:
  KC_BOOTSTRAP_ADMIN_USERNAME: "admin"
  KC_BOOTSTRAP_ADMIN_PASSWORD: "admin"
  KC_HTTP_PORT: "8080"
  DEBUG: "true"
  DEBUG_PORT: "*:5005"
  command: ["start-dev"]

2. Start the container:

docker compose up

3. Observe the startup failure with JDWP transport errors.

Repeat with Keycloak 26.3.5 using the same setup — the container starts successfully and the debugger listens on port 5005.

Anything else?

No response