Azure: User 'docker-user' is not added to 'docker' group on default Ubuntu 16.04 instance.

[twang2218]

I created a Azure docker host to give the Azure driver a try, and after the docker host has been created, I can run docker info from my local laptop if I use env $(docker-machine env a1) first. However, I cannot run docker info if I directly ssh into the Azure host.

The reason is the default user docker-user are not added to the docker group, which cause the problem.

Although, it's not the deal breaker, I still can use sudo docker to workaround it, it would be better that adding the 'AZURE_SSH_USER' to the docker group, so after docker-machine ssh, people will not run into the error with confusion:

Cannot connect to the Docker daemon. Is the docker daemon running on this host?

[ahmetb]

@twang2218 this is not Azure specific. I brought this up before but it is by design and meant to be consistent across all distros on all cloud providers. See #3178 as this is just a duplicate of that.

[twang2218]

@ahmetalpbalkan Thank you for pointing out the previous issue, but I think the design should be changed.

Here is the list of some current status of default user and whether they are in docker group by machine driver.

Driver	default user	in docker group?
amazonec2	ubuntu	No
azure	docker-user	No
digitalocean	root	-
google	docker-user	No
rackspace	root	-
virtualbox	docker	Yes

As you can said, because it's by design, the default user are not added to the docker group for most drivers. However, the virtualbox's default user, docker is in the docker group. so it's not a consistent experience.

And if people come from experience of using Docker for Mac/Windows, which is not necessary of using sudo, they would also feel the inconsistent experience.

I think adding default user to docker group will have better and consistent user experience.

[tronicum]

I experienced that a machine 0.9.0-rc2 with target RHEL 7.3 does not add docker group, too. I miss it though as my old installs on Fedora did have docker group installed by default.

Is there a complete matrix somwhere?