slash characters in tags yields erratic behavior

[gregzuro]

tl;dr:

• discrimination between tags containing one '/' and repository names is weak.
• multiple '/' characters in tags is not possible (should be).

Example:

 $ docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 50
Storage Driver: sdc
 SDCAccount: gregzuro
Logging Driver: json-file
Plugins:
 Volume: 
 Network: 
Swarm: 
 NodeID: 
 Is Manager: false
 Node Address: 
Security Options:
Kernel Version: 3.12.0-1-amd64
Operating System: SmartDataCenter
OSType: linux
Architecture: x86_64
CPUs: 0
Total Memory: 0 B
Name: us-west-1
ID: ad77aa84-aaef-4ebc-b68f-36725427c008
Docker Root Dir: 
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
WARNING: No kernel memory limit support
WARNING: No oom kill disable support
WARNING: No cpu cfs quota support
WARNING: No cpu cfs period support
WARNING: No cpu shares support
WARNING: No cpuset support
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
consul              0.7.2               2b13d9b85f83        2 days ago          0 B
vault               0.6.4               7543e293bb89        5 days ago          0 B
grafana/grafana     4.0.1               d0aaace0748e        2 weeks ago         0 B
influxdb            1.0.2-alpine        b5d995eee90d        9 weeks ago         0 B

$ docker tag 7543e293bb89 a
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
consul              0.7.2               2b13d9b85f83        2 days ago          0 B
a                   latest              7543e293bb89        5 days ago          0 B
vault               0.6.4               7543e293bb89        5 days ago          0 B
grafana/grafana     4.0.1               d0aaace0748e        2 weeks ago         0 B
influxdb            1.0.2-alpine        b5d995eee90d        9 weeks ago         0 B

$ docker tag 7543e293bb89 a/b
Error response from daemon: invalid repository namespace, must be between 2 and 255 characters: a (3d7e59bb-33fc-42ef-8060-89add308f839)

$ docker tag 7543e293bb89 aa/b
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
consul              0.7.2               2b13d9b85f83        2 days ago          0 B
aa/b                latest              7543e293bb89        5 days ago          0 B
a                   latest              7543e293bb89        5 days ago          0 B
vault               0.6.4               7543e293bb89        5 days ago          0 B
grafana/grafana     4.0.1               d0aaace0748e        2 weeks ago         0 B
influxdb            1.0.2-alpine        b5d995eee90d        9 weeks ago         0 B

$ docker tag 7543e293bb89 aa/b/c
Error response from daemon: invalid repository name, may only contain [a-z0-9_.-] characters: b/c (f43c5a21-c515-422a-ad60-72f6db72356d)