access remote network from within docker container - docker

Question

I have a Docker Host that is connected to a non-default route network. My problem is now that I can't reach this Network from within the Docker Containers on the Docker Host.
Primary IP: 189.69.77.21 (default route)
Secondary IP: 192.168.77.21
Routing is like the following:
[root#mgmt]# route -n
Kernel IP Routentabelle
Ziel Router Genmask Flags Metric Ref Use Iface
0.0.0.0 189.69.77.1 0.0.0.0 UG 0 0 0 enp0s31f6
189.69.77.1 0.0.0.0 255.255.255.255 UH 0 0 0 enp0s31f6
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0
192.168.77.0 0.0.0.0 255.255.255.0 U 0 0 0 enp0s31f6.4000
and IPtables untouched:
[root#mgmt]# iptables -L -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy DROP)
target prot opt source destination
DOCKER-ISOLATION-STAGE-1 all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
DOCKER all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain DOCKER (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 172.17.0.2 tcp dpt:3000
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
target prot opt source destination
DOCKER-ISOLATION-STAGE-2 all -- 0.0.0.0/0 0.0.0.0/0
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain DOCKER-ISOLATION-STAGE-2 (1 references)
target prot opt source destination
DROP all -- 0.0.0.0/0 0.0.0.0/0
RETURN all -- 0.0.0.0/0 0.0.0.0/0
I start the Docker Container with the following:
docker run -d --restart=unless-stopped -p 127.0.0.1:3000:3000/tcp --name mongoclient -e MONGOCLIENT_DEFAULT_CONNECTION_URL=mongodb://192.168.77.21:27017,192.168.77.40:27017,192.168.77.41:27017/graylog?replicaSet=ars0 -e ROOT_URL=http://192.168.77.21/nosqlclient mongoclient/mongoclient
I can reach the container (via NGINX Proxy) over Network but the container itself can only ping/reach the Docker Host IP and not others.
node#1c5cf0e8d14c:/opt/meteor/dist/bundle$ ping 192.168.77.21
PING 192.168.77.21 (192.168.77.21) 56(84) bytes of data.
64 bytes from 192.168.77.21: icmp_seq=1 ttl=64 time=0.078 ms
64 bytes from 192.168.77.21: icmp_seq=2 ttl=64 time=0.080 ms
64 bytes from 192.168.77.21: icmp_seq=3 ttl=64 time=0.079 ms
^C
--- 192.168.77.21 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
rtt min/avg/max/mdev = 0.078/0.079/0.080/0.000 ms
node#1c5cf0e8d14c:/opt/meteor/dist/bundle$ ping 192.168.77.40
PING 192.168.77.40 (192.168.77.40) 56(84) bytes of data.
^C
--- 192.168.77.40 ping statistics ---
240 packets transmitted, 0 received, 100% packet loss, time 239000ms
So my question is, how can I make the Docker Container reach the hosts on the Network? My goal is to have a running mongoclient via Docker that can be used to manage the MongoDB ReplicaSet that is in that additional private Network.

Answer 1

You can use the network host in the container. So the container is use the host network and you can access the container and host network.
Here is the documentation:
https://docs.docker.com/network/host/
BR
Carlos