Agent healthcheck fails because it begins to call http://localhost:8080/healthcheck instead of the dozzle host at 7007

[BartschLabs]

🔍 Check for existing issues

• Completed

How is Dozzle deployed?

Agents

📦 Dozzle version

10.3.0

✅ Command used to run Dozzle

My docker-compose.yml:

services:
  service1:
    container_name: ${COMPOSE_PROJECT_NAME}    # COMPOSE_PROJECT_NAME is the stack name from Portainer
    image: amir20/dozzle:latest
    restart: unless-stopped
    command: agent
    ports:
      - 7007:7007
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    healthcheck:
      test: ["CMD", "/dozzle", "healthcheck"]
      ## Increased this from 20 to 40s due to command sometimes trying to initially hit port 8080 instead of 7007
      start_period: 40s
      timeout: 3s
      interval: 15s
      retries: 3

🐛 Describe the bug / provide steps to reproduce it

The error that shows up in the health check log is:

Exit: 1

{"level":"info","version":"v10.3.0","address":":8080","base":"/","time":"2026-04-11T23:21:24Z","message":"Making HTTP request to server"} {"level":"info","version":"v10.3.0","url":"http://localhost:8080/healthcheck","time":"2026-04-11T23:21:24Z","message":"performing healthcheck"} {"level":"fatal","version":"v10.3.0","error":"Get \"http://localhost:8080/healthcheck\": dial tcp [::1]:8080: connect: connection refused","time":"2026-04-11T23:21:24Z","message":"Failed to run command"}

Whereas a healthy dozzle agent health check log is:

Exit: 0

{"level":"info","version":"v10.3.0","address":"[::]:7007","time":"2026-04-11T23:41:14Z","message":"Making RPC request to agent"}

To reproduce, I just have to leave the particular dozzle agent container running for hours or days and then it eventually happens.

💻 Environment

:~# docker system info
Client: Docker Engine - Community
 Version:    28.5.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.29.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.40.3
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 13
  Running: 11
  Paused: 0
  Stopped: 2
 Images: 27
 Server Version: 28.5.1
 Storage Driver: overlay2
  Backing Filesystem: zfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: true
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: b98a3aace656320842a23f4a392a33f46af97866
 runc version: v1.3.0-0-g4ca628d1
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.8.12-20-pve
 Operating System: Debian GNU/Linux 12 (bookworm)
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 2.246GiB
 Name: DebianCT4
 ID: 
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false
 Default Address Pools:
   Base: 172.30.0.0/16, Size: 24

📜 Dozzle logs are required for debugging purposes. You may need to enable debug mode. See https://dozzle.dev/guide/debugging.

Attached is a log where the agent is working correctly. Wouldn't you know that by enabling debug and restarting the agent, it started working correctly...but will eventually start exhibiting the problem. I'll add the log entries once that starts happening.

dozzle-agent-2026-04-11T23-52-46.log

📸 If applicable, add screenshots to help explain your bug

No response

[amir20]

Some exploration suggests this is an IPv6 problem. I'll see if its an easy fix.

[amir20]

I was wrong. I was trying to use --health-cmd="/dozzle healthcheck" which won't work with CLI. Using compose worked. I have an agent running now. I'll wait a few days to see what happens.

[amir20]

@BartschLabs my agent has been running for 2 days. It's been healthy. I am not sure what's happening in your case. I made some improvements in #4617 but I wasn't able to reproduce anything in latest. So I'll keep this open for a bit. I think this is specific to your instance.

[BartschLabs]

Thanks for looking into it. Two of my ten agents are currently unhealthy. Restarting each of them didn't help, but I just updated them to 10.3.2 and now they're healthy.

[BartschLabs]

I forgot that I had turned on debug logging on the agents, so I didn't look at the log before restarting the agents and updating them. I'll try to remember to trace back in the log next time it happens.

[amir20]

Gonna move to this discussion. I don't think it's a bug on my side.