"docker run" does not connect to more than one network

[djmaze]

Description

Steps to reproduce the issue:

1. Create two networks:

    docker network create test
    docker network create test2
   

2. Try to run a container attached to both networks and output the IPs:

    docker run -it --rm --network test --network test2 busybox ip a
   

Describe the results you received:

There is only one network present (apart from the loopback one). Example output:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
45343: eth0@if45344: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
    link/ether 02:42:ac:16:00:02 brd ff:ff:ff:ff:ff:ff
    inet 172.22.0.2/16 scope global eth0
       valid_lft forever preferred_lft forever

Describe the results you expected:

There should be three interfaces (including loopback) including the two networks specified.

Additional information you deem important (e.g. issue happens only occasionally):

docker run seems to only take into account the last network specified at the commandline.

Output of docker version:

Client:
 Version:      17.10.0-ce
 API version:  1.33
 Go version:   go1.8.3
 Git commit:   f4ffd25
 Built:        Tue Oct 17 19:04:16 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.10.0-ce
 API version:  1.33 (minimum version 1.12)
 Go version:   go1.8.3
 Git commit:   f4ffd25
 Built:        Tue Oct 17 19:02:56 2017
 OS/Arch:      linux/amd64
 Experimental: false

Output of docker info:

Containers: 5
 Running: 4
 Paused: 0
 Stopped: 1
Images: 8
Server Version: 17.10.0-ce
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: active
 NodeID: novju2obbkwighigowx8slr76
 Is Manager: true
 ClusterID: 2dbj37zxgyf0iv9pk0ncozg6f
 Managers: 1
 Nodes: 3
 Orchestration:
  Task History Retention Limit: 5
 Raft:
  Snapshot Interval: 10000
  Number of Old Snapshots to Retain: 0
  Heartbeat Tick: 1
  Election Tick: 3
 Dispatcher:
  Heartbeat Period: 5 seconds
 CA Configuration:
  Expiry Duration: 3 months
  Force Rotate: 0
 Autolock Managers: false
 Root Rotation In Progress: false
 Node Address: 192.158.50.11
 Manager Addresses:
  192.158.50.11:2377
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 06b9cb35161009dcb7123345749fef02f7cea8e0
runc version: 0351df1c5a66838d0c392b4ac4cf9450de844e2d
init version: 949e6fa
Security Options:
 apparmor
 seccomp
  Profile: default
Kernel Version: 4.4.0-98-generic
Operating System: Ubuntu 16.04.3 LTS
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 992.1MiB
Name: longhorn-01
ID: FS4U:GCWE:MPIQ:EFZU:Y43S:GCLM:PQX3:PYHR:5BIY:A4KA:Q5GU:TNVV
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

WARNING: No swap limit support

Additional environment details (AWS, VirtualBox, physical, etc.):

This is on Ubuntu 16.04, but the same happens on Arch Linux as well. Tested on Docker swarm hosts only.

[thaJeztah]

Thanks for reporting; allowing multiple networks to be provided on docker run has come up a few times in the past; #17750, #17289, and #17796).

The reason it's currently not supported, is that there are some options that can only be provided on a per-container basis (e.g. --network-alias).

I opened a proposal for implementing an "advanced" syntax for --network, so that these options can be specified per-network; see #31964, and docker/cli#317, which implements this in the CLI.

[thaJeztah]

• This should be implemented now in api: Allow ContainerCreate to take several EndpointsConfig for >= API 1.44 #45906, which will be part of the v25.0.0 release