Unable to reach docker swarm services externally

[chrisvx (christian valaer)]

I’m running into an issue with setting up a docker swarm service. I have a 5-node cluster running on ubuntu 24.

Server Version: 27.1.1

Steps to reproduce:

1. docker service create --name test_web --replicas 3 --publish published=8080,target=80 nginxdemos/hello

root@lnx01:/etc/docker# docker service create --name test_web --replicas 3 --publish published=8080,target=80 nginxdemos/hello
cmw0jr7rv3rvhnymntgm9ljzn
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service cmw0jr7rv3rvhnymntgm9ljzn converged

2. Service is running
   root@lnx01:/etc/docker# docker service ls
   ID NAME MODE REPLICAS IMAGE PORTS
   cmw0jr7rv3rv test_web replicated 3/3 nginxdemos/hello:latest *:8080->80/tcp

3. Firewall Port is open

root@lnx01:/etc/docker# ufw status
Status: active

To Action From

---

9090 ALLOW Anywhere
10000 ALLOW Anywhere
443 ALLOW Anywhere
OpenSSH ALLOW Anywhere
20/tcp ALLOW Anywhere
21/tcp ALLOW Anywhere
990/tcp ALLOW Anywhere
4000:5000/tcp ALLOW Anywhere
8080 ALLOW Anywhere
2377 ALLOW Anywhere
7946 ALLOW Anywhere
4789 ALLOW Anywhere
8181 ALLOW Anywhere
80 ALLOW Anywhere
9090 (v6) ALLOW Anywhere (v6)
10000 (v6) ALLOW Anywhere (v6)
443 (v6) ALLOW Anywhere (v6)
OpenSSH (v6) ALLOW Anywhere (v6)
20/tcp (v6) ALLOW Anywhere (v6)
21/tcp (v6) ALLOW Anywhere (v6)
990/tcp (v6) ALLOW Anywhere (v6)
4000:5000/tcp (v6) ALLOW Anywhere (v6)
8080 (v6) ALLOW Anywhere (v6)
2377 (v6) ALLOW Anywhere (v6)
7946 (v6) ALLOW Anywhere (v6)
4789 (v6) ALLOW Anywhere (v6)
8181 (v6) ALLOW Anywhere (v6)
80 (v6) ALLOW Anywhere (v6)

root@lnx01:/etc/docker#

Here is my node setup:

root@lnx01:/etc/docker# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
dee1j2hn5g247wj3nrz0d45gr * lnx01 Ready Active Reachable 27.1.1
kzosfivryenvhfpcx7gynzsab lnx02 Ready Active 27.1.1
vxqamidvrfph7k0qssijrky5d lnx03 Ready Active 27.1.1
mznsbcpg5vml8fryguwoyyn25 lnx04 Ready Active Reachable 27.1.1
ra7797twxbgz0eudlff080z4d lnx05 Ready Active Leader 27.1.1
root@lnx01:/etc/docker#

I can run this container locally and successfully reach the container externally:

root@lnx01:/etc/docker# docker run -p 8080:80 -d nginxdemos/hello
208551d6b1722a072d9197f796744ea4ae33db0905c000a7a928514e83f6403ddock

My default address pool is Default Address Pool: 10.0.0.0/8 and I am wondering if it is an issue. I found this forum post that seems like it could be related to my issue, unfortunatley, the link is dead that goes to the solution.

All deployed services within a swarm are unreachable, while containers deployed normally work fine

Is it safe to assume that 10.100.4.5 is one of your nodes ip? The default address pool is 10.0.0.0/8, see: docker info --format '{{json .Swarm.Cluster.DefaultAddrPool}}' If this is the case, you might find this blog post helpful - you can safely ignore that it refers to Docker EE, the problem and solution is valid for Docker CE as well. You need to alter default-addr-pool either when initiating the swarm or by modifying each node’s /etc/docker/daemon.json configuration file (and restart the d…

Can anyone assist? I’m planning on using this for a school project but I’m just banging my head against a wall.

[meyay (Metin Y.)]

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