Inside the docker-compose.yaml
I define 4 different networks:
networks:
vpp-nw:
vpp-client:
vpp-server:
vpp-db:
which use the following network addresses respectively:
172.20.0.x
172.21.0.x
172.22.0.x
172.23.0.x
One of the containers I use, connects to all 4 networks (with the same order):
# part of docker-compose.yaml
services:
my_tool:
build: ./my_tool
image: tgogos/my_tool
container_name: my_tool_docker_comp
hostname: my_tool
privileged: true
links:
- my_db
networks:
- vpp-nw
- vpp-client
- vpp-server
- vpp-db
ports:
- "8888:8888"
Is there a way to define which interface will connect to each network? For example, I would like:
eth0
to connect to the first (vpp-nw)eth1
to connect to the second (vpp-client)eth2
to connect to the third (vpp-server)eth3
to connect to the fourth (vpp-db)Below you can see an ifconfig
output of this container. NICs seem to connect to each network in an arbitrary way every time I docker-compose down
| docker-compose up
...
eth0 Link encap:Ethernet HWaddr 02:42:ac:15:00:03
inet addr:172.21.0.3 Bcast:0.0.0.0 Mask:255.255.0.0
eth1 Link encap:Ethernet HWaddr 02:42:ac:17:00:03
inet addr:172.23.0.3 Bcast:0.0.0.0 Mask:255.255.0.0
eth2 Link encap:Ethernet HWaddr 02:42:ac:14:00:02
inet addr:172.20.0.2 Bcast:0.0.0.0 Mask:255.255.0.0
eth3 Link encap:Ethernet HWaddr 02:42:ac:16:00:03
inet addr:172.22.0.3 Bcast:0.0.0.0 Mask:255.255.0.0
Further reading, github issues:
This isn't an answer, but it is a confirmation of the behavior you've reported along with complete reproducers that could be used to file a bug report.
I am able to reproduce your behavior. I think it's a bug in docker-compose
, since the networks
key on your service is an ordered list. I would expect networks to be assigned to interfaces in the order in which they are listed in the file.
Using this docker-compose.yml
(in a directory named nwtest
):
version: "2"
services:
server:
image: alpine
command: sleep 999
networks:
- nw0
- nw1
- nw2
- nw3
networks:
nw0:
nw1:
nw2:
nw3:
And this shell script:
#!/bin/sh
docker-compose up -d
for nw in 0 1 2 3; do
nw_cidr=$(docker network inspect -f '{{ (index .IPAM.Config 0).Subnet }}' \
nwtest_nw${nw})
if_cidr=$(docker exec -it nwtest_server_1 ip addr show eth${nw} |
awk '$1 == "inet" {print $2}')
nw_net=$(ipcalc -n $nw_cidr | cut -f2 -d=)
if_net=$(ipcalc -n $if_cidr | cut -f2 -d=)
echo "nw${nw} $nw_net eth${nw} ${if_net}"
if [ "$if_net" != "$nw_net" ]; then
echo "MISMATCH: nw${nw} = $nw_net, eth${nw} = $if_net" >&2
fi
done
docker-compose stop
You can quickly verify the problem:
$ sh runtest.sh
Starting nwtest_server_1
nw0 192.168.32.0 eth0 192.168.32.0
nw1 192.168.48.0 eth1 192.168.48.0
nw2 192.168.64.0 eth2 192.168.80.0
MISMATCH: nw2 = 192.168.64.0, eth2 = 192.168.80.0
nw3 192.168.80.0 eth3 192.168.64.0
MISMATCH: nw3 = 192.168.80.0, eth3 = 192.168.64.0
Stopping nwtest_server_1 ...
Furthermore, this problem seems to be specific to docker-compose
; if you create a Docker container with docker run
and then attach multiple networks, they are always assigned to interfaces sequentially as you would expect. The test script for that is:
#!/bin/sh
docker rm -f nwtest_server_1
docker run -d --name nwtest_server_1 --network nwtest_nw0 \
alpine sleep 999
for nw in 1 2 3; do
docker network connect nwtest_nw${nw} nwtest_server_1
done
for nw in 0 1 2 3; do
nw_cidr=$(docker network inspect -f '{{ (index .IPAM.Config 0).Subnet }}' \
nwtest_nw${nw})
if_cidr=$(docker exec -it nwtest_server_1 ip addr show eth${nw} |
awk '$1 == "inet" {print $2}')
nw_net=$(ipcalc -n $nw_cidr | cut -f2 -d=)
if_net=$(ipcalc -n $if_cidr | cut -f2 -d=)
echo "nw${nw} $nw_net eth${nw} ${if_net}"
if [ "$if_net" != "$nw_net" ]; then
echo "MISMATCH: nw${nw} = $nw_net, eth${nw} = $if_net" >&2
fi
done
docker rm -f nwtest_server_1