docker service replicas remain 0/1

Question

I am trying out docker swarm with 1.12 on my Mac. I started 3 VirtualBox VMs, created a swarm cluster of 3 all fine.

docker@redis1:~$ docker node ls  ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS 2h1m8equ5w5beetbq3go56ebl    redis3  Ready Active  8xubu8g7pzjvo34qdtqxeqjlj    redis2  Ready Active Reachable  cbi0lyekxmp0o09j5hx48u7vm *  redis1  Ready Active Leader 

However, when I create a service, I see no errors yet replicas always displays 0/1:

docker@redis1:~$ docker service create --replicas 1 --name hello ubuntu:latest /bin/bash 76kvrcvnz6kdhsmzmug6jgnjv docker@redis1:~$ docker service ls ID            NAME   REPLICAS  IMAGE          COMMAND 76kvrcvnz6kd  hello  0/1       ubuntu:latest  /bin/bash docker@redis1:~$ docker ps CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES 

What could be the problem? Where do I look for logs? Thanks!

Answer 1

The problem is that your tasks (calling bin/bash) exits quickly since it's not doing anything.

If you look at the tasks for your service, you'll see that one is started and then shutdown within seconds. Another one is then started, shutdown and so on, since you're requested that 1 task be running at all times.

docker service ps hello 

If you use ubuntu:latest top for instance, the task will stay up running.

Answer 2

This also can happen if you specify a volume in your compose file that is bound to a local directory that does not exist.

If you look at the log (on some Linux systems, this is journalctl -xe), you'll see which volume can't be bound.