docker-node-identities

A tool that will create/remove users and groups on a docker node, if required by a container.

Flags

$ docker-node-identities -h
Usage of docker-node-identities:
  -debug
    	Show debug info
  -docker-api-version float
    	Docker API version (default 1.24)
  -docker-cert-path string
    	Path to TLS files
  -docker-host string
    	Daemon socket to connect to (default "unix:///var/run/docker.sock")
  -docker-tls-verify
    	Use TLS and verify the remote
  -group-label string
    	Label containing group config (default "docker.node.identities.group")
  -user-label string
    	Label containing user config (default "docker.node.identities.user")
  -version
    	Show version

Labels

Group

Content of the group label is expected to be name:password:gid:members - if you recognize this syntax, it's because you will find it in /etc/group.

Note: members will be ommited.

User

Content of the user label is expected to be username:password:uid:gid:comment:home:shell - and yes, you might already have guessed it, it's just like /etc/passwd.

Install on docker node

To keep things running, you can use systemd:

wget -O /usr/local/bin/docker-node-identities https://github.com/urlund/docker-node-identities/releases/download/1.0.4/docker-node-identities-linux-amd64
wget -O /etc/systemd/system/docker-node-identities.service https://raw.githubusercontent.com/urlund/docker-node-identities/master/docker-node-identities.service
chmod +x /usr/local/bin/docker-node-identities
service docker-node-identities start

Now docker-node-identities should be running and ready to keep your users/groups in sync.

Examples

The most basic example will create a user johndoe (uid: 1001), and a group johndoe (gid: 1001)

docker run -d -p 80:80 -l "docker.node.identities.user=johndoe::1001" nginx

This properly wouldn't make much sense if you are running a single instance, but let's assume you are running a service of 10 (or more) replicas, it would be rather trivial to create the same user on all nodes running or service, so this will make your day:

docker service create -p 80:80 -l "docker.node.identities.group=thedoes::1010" -l "docker.node.identities.user=johndoe::1001:1010" nginx

Now all nodes running a replica will have the user johndoe (uid: 1001) created, and added to the group thedoes (gid: 1010). Scaling the service to 5 and the nodes no longer running a replica will have the user and group removed.