Deploy app on a cluster but cannot access it successfully

user_4428471 0
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I'm now learning to use docker follow get-started documents, but in part 4--Swarms I've met some problem. That is when deployed my app on a cluster, I cannot access it successfully.

docker@myvm1:~$ docker stack ps getstartedlab
ID                  NAME                  IMAGE                     NODE                DESIRED STATE       CURRENT STATE              ERROR               PORTS
gsueb9ejeur5        getstartedlab_web.1   zhugw/get-started:first   myvm1               Running             Preparing 11 seconds ago
ku13wfrjp9wt        getstartedlab_web.2   zhugw/get-started:first   myvm2               Running             Preparing 11 seconds ago
vzof1ybvavj3        getstartedlab_web.3   zhugw/get-started:first   myvm1               Running             Preparing 11 seconds ago
lkr6rqtqbe6n        getstartedlab_web.4   zhugw/get-started:first   myvm2               Running             Preparing 11 seconds ago
cpg91o8lmslo        getstartedlab_web.5   zhugw/get-started:first   myvm2               Running             Preparing 11 seconds ago

docker@myvm1:~$ curl 'http://localhost'
curl: (7) Failed to connect to localhost port 80: Connection refused

āžœ  ~ docker-machine ls
NAME    ACTIVE   DRIVER       STATE     URL                         SWARM   DOCKER        ERRORS
myvm1   -        virtualbox   Running   tcp://192.168.99.101:2376           v17.06.0-ce
myvm2   -        virtualbox   Running   tcp://192.168.99.100:2376           v17.06.0-ce

āžœ  ~ curl 'http://192.168.99.101'
curl: (7) Failed to connect to 192.168.99.101 port 80: Connection refused

What's wrong?

In addition, very strange. After adding below content in docker-compose.yml I found above question resolved automatically

visualizer:
    image: dockersamples/visualizer:stable
    ports:
      - "8080:8080"
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"
    deploy:
      placement:
        constraints: [node.role == manager]
    networks:
      - webnet

but this time the new added visualizer does not work

docker@myvm1:~$ docker stack ps getstartedlab
ID                  NAME                         IMAGE                             NODE                DESIRED STATE       CURRENT STATE             ERROR               PORTS
xomsv2l5nc8x        getstartedlab_web.1          zhugw/get-started:first           myvm1               Running             Running 7 minutes ago
ncp0rljod4rc        getstartedlab_visualizer.1   dockersamples/visualizer:stable   myvm1               Running             Preparing 7 minutes ago
hxddan48i1dt        getstartedlab_web.2          zhugw/get-started:first           myvm2               Running             Running 7 minutes ago
dzsianc8h7oz        getstartedlab_web.3          zhugw/get-started:first           myvm1               Running             Running 7 minutes ago
zpb6dc79anlz        getstartedlab_web.4          zhugw/get-started:first           myvm2               Running             Running 7 minutes ago
pg96ix9hbbfs        getstartedlab_web.5          zhugw/get-started:first           myvm2               Running             Running 7 minutes ago

from above you know it's always preparing.

My whole docker-compose.yml 

version: "3"
services:
  web:
    # replace username/repo:tag with your name and image details
    image: zhugw/get-started:first
    deploy:
      replicas: 5
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "80:80"
    networks:
      - webnet
  visualizer:
    image: dockersamples/visualizer:stable
    ports:
      - "8080:8080"
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"
    deploy:
      placement:
        constraints: [node.role == manager]
    networks:
      - webnet
networks:
  webnet:
docker-swarm
6 Answers

Had this problem while learning too.

It's because your none clustered image is still running from step 2 and the clustered image you just deployed uses the same port mapping (4000:80) in the docker-compose.yml file.

You have two options:

  1. Go into your docker-compose.yml and change the port mapping to something else e.g 4010:80 and then redeploy your cluster with the update. Then try: http://localhost:4010

  2. Remove the container you created in step 2 of the guide that's still running and using port mapping 4000:80

user_99588500

Open port 7946 TCP/UDP and port 4789 UDP between the swarm nodes. Use the ingress network. Please let me know if it works, thanks.

user_59798330

If you are using Docker toolbox for mac, then you should check this out.

user_43402610

I had the same problem. As it says in the tutorial (see "Having connectivity trouble?") the following ports need to be open:

  • Port 7946 TCP/UDP for container network discovery.
  • Port 4789 UDP for the container ingress network.

So I executed the following before the swarm init (right after creation of myvm1 and myvm2) and then later could access the service e.g. in the browser with IP_node:4000

$ docker-machine ssh myvm1 "sudo iptables -I INPUT -p tcp --dport 7946 --syn -j ACCEPT"
$ docker-machine ssh myvm2 "sudo iptables -I INPUT -p tcp --dport 7946 --syn -j ACCEPT"
$ docker-machine ssh myvm1 "sudo iptables -I INPUT -p udp --dport 7946 -j ACCEPT"
$ docker-machine ssh myvm2 "sudo iptables -I INPUT -p udp --dport 7946 -j ACCEPT"
$ docker-machine ssh myvm1 "sudo iptables -I INPUT -p udp --dport 4789 -j ACCEPT"
$ docker-machine ssh myvm2 "sudo iptables -I INPUT -p udp --dport 4789 -j ACCEPT"

Hope it helps others.

user_66100370
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