Host environment variables with docker stack deploy
Yes, this works when you combine two concepts:
- Swarm node labels, of which Hostname is one of the built-in ones.
- Swarm service go templates, which also work in stack files.
This would pull in the hostname to the ENV value of DUDE for each container to be the host that it's running on:
version: '3.4'services: nginx: image: nginx environment: DUDE: "{{.Node.Hostname}}" deploy: replicas: 3
It works if you run the docker command through env.
env JMX_HOSTNAME="${JMX_HOSTNAME}" docker stack deploy -c docker-compose.yml mystack
Credit to GitHub issue that pointed me in the right direction.
I found another way for when you have many environment variables. The same method also works with docker-compose up
sudo -E docker stack deploy -c docker-compose.yml mystack
instead of
env foo="${foo}" bar="${bar}" docker stack deploy -c docker-compose.yml mystack
sudo -E
man description;
-E, --preserve-env Indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the user does not have permission to preserve the environment.