execute a command within docker swarm service

Question

1. Initialize swarm mode:

   root@ip-172-31-44-207:/home/ubuntu# docker swarm init --advertise-addr 172.31.44.207
   
   Swarm initialized: current node (4mj61oxcc8ulbwd7zedxnz6ce) is now a manager.
   
   To add a worker to this swarm, run the following command:
   

2. Join the second node:

   docker swarm join 
   --token SWMTKN-1-4xvddif3wf8tpzcg23tem3zlncth8460srbm7qtyx5qk3ton55-6g05kuek1jhs170d8fub83vs5 
   172.31.44.207:2377
   

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

# start 2 services
docker service create continuumio/miniconda3 

docker service create --name redis redis:3.0.6


root@ip-172-31-44-207:/home/ubuntu# docker service ls
ID            NAME        REPLICAS  IMAGE                   COMMAND
2yc1xjmita67  miniconda3  0/1       continuumio/miniconda3
c3ptcf2q9zv2  redis       1/1       redis:3.0.6

As shown above, redis has it's replica while miniconda does not seem to be replicated.

I do usually log-in to miniconda container to type these commands:

/opt/conda/bin/conda install jupyter -y --quiet && mkdir /opt/notebooks && /opt/conda/bin/jupyter notebook --notebook-dir=/opt/notebooks --ip='*' --port=8888 --no-browser

The problem is that docker exec -it XXX bash command does not work with swarm mode.

Answer 1

You can execute commands by filtering container name without needing to pass the entire swarm container hash, just by the service name. Like this:

docker exec $(docker ps -q -f name=servicename) ls