无法从 docker 的容器内连接到 postgres 容器

Question

I made two different container with different images, both ended with the same ip as i create one afte deleting the previus one, both used a postgresql image and i was unable to connect to the container holding that specific ip 192.168.3.2, but from within the container with postgres i could connect using that ip with psql, but trying from another container resulted in

root@23c9e6ee234c:/# psql -h 192.168.3.2 -U odoo -W -d postgres -p 5432
Password for user odoo: 
psql: could not connect to server: Connection refused
    Is the server running on host "192.168.3.2" and accepting
    TCP/IP connections on port 5432?

But the same command would succeed with a another postgres container. The config of the unreachable container is:

listen_addresses = '*'

                                    # comma-separated list of addresses;
                                    # defaults to 'localhost'; use '*' for all
                                    # (change requires restart)
#port = 5432                            # (change requires restart)

i think its ok, and the ip tables (generated by docker and not modified by me are)

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            

Chain FORWARD (policy DROP)
target     prot opt source               destination         
DOCKER-ISOLATION  all  --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED
DOCKER     all  --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere            

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain DOCKER (1 references)
target     prot opt source               destination         
ACCEPT     tcp  --  anywhere             192.168.3.11         tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.15         tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.10         tcp dpt:8072
ACCEPT     tcp  --  anywhere             192.168.3.10         tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.10         tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.14         tcp dpt:8072
ACCEPT     tcp  --  anywhere             192.168.3.14         tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.14         tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.7          tcp dpt:8072
ACCEPT     tcp  --  anywhere             192.168.3.7          tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.7          tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.9          tcp dpt:8072
ACCEPT     tcp  --  anywhere             192.168.3.9          tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.9          tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.13         tcp dpt:hello-port
ACCEPT     tcp  --  anywhere             192.168.3.13         tcp dpt:mysql
ACCEPT     tcp  --  anywhere             192.168.3.13         tcp dpt:https
ACCEPT     tcp  --  anywhere             192.168.3.13         tcp dpt:http
ACCEPT     tcp  --  anywhere             192.168.3.13         tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.6          tcp dpt:postgres
ACCEPT     tcp  --  anywhere             192.168.3.3          tcp dpt:8071
ACCEPT     tcp  --  anywhere             192.168.3.3          tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.3          tcp dpt:ipp
ACCEPT     tcp  --  anywhere             192.168.3.3          tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.4          tcp dpt:8071
ACCEPT     tcp  --  anywhere             192.168.3.4          tcp dpt:8069
ACCEPT     tcp  --  anywhere             192.168.3.4          tcp dpt:ipp
ACCEPT     tcp  --  anywhere             192.168.3.4          tcp dpt:ssh
ACCEPT     tcp  --  anywhere             192.168.3.2          tcp dpt:postgres
ACCEPT     tcp  --  anywhere             192.168.3.2          tcp dpt:ssh

Chain DOCKER-ISOLATION (1 references)
target     prot opt source               destination         
RETURN     all  --  anywhere             anywhere            

For instance, i cant connect to 192.168.3.6, but no to 3.2, and my docker version is:

Client:
 Version:      17.04.0-ce
 API version:  1.28
 Go version:   go1.7.5
 Git commit:   4845c56
 Built:        Mon Apr  3 18:01:50 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.04.0-ce
 API version:  1.28 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   4845c56
 Built:        Mon Apr  3 18:01:50 2017
 OS/Arch:      linux/amd64
 Experimental: false

And the network ls:

NETWORK ID          NAME                DRIVER              SCOPE
496515e2ff28        bridge              bridge              local
50b61710b459        host                host                local
e061da58f729        none                null                local

I must point that the container used to be reachable until recently, after i restarted the docker service with systemctl stop docker and initiated afterwards.

And the containers

3198ba01cb43        postgres:9.4            "docker-entrypoint..."   3 years ago         Up 8 minutes        0.0.0.0:8122->22/tcp, 0.0.0.0:8132->5432/tcp                                                                                 educosal_db
23c9e6ee234c        ubuntu                  "/bin/bash"              3 years ago         Up 3 hours          0.0.0.0:8069->8069/tcp, 0.0.0.0:2022->22/tcp, 0.0.0.0:2631->631/tcp, 0.0.0.0:2071->8071/tcp                                  odoo10

from the odoo10 i could reach other postgres containers, but not the one with 3.2, and both have ip in the same range.

What could be the problem? Are the iptables bad (of which my knowledge is null)? Could this be a docker bug?

Answer 1

Postgres 9.4 utilizes a different way to add database access variables, then what 9.5 has.

Maybe your Docker Engine version realizes it's 9.4 and Postgres 9.5 has another format to add database access variables.

This link has more information on what my train of thought is after reading your question. Docker Hub Docs

Disclosure: I have only taken courses on Docker.