There a many ways to find the ip of a container. Some of the methods i am listing down.

[root@localhost ~]# docker run -d –name mylinux rhel7
9f7213f3c373b06a6a5d8d762bd05c2282db9e1ecb0da421b8280e07291c0535

docker inspect

"NetworkSettings": {
            "Bridge": "",
            "SandboxID": "f8b8d1847392e520fc79cff3c3637fdfbd28aaded2290ad851aaab3adce23c6f",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": null,
            "SandboxKey": "/var/run/docker/netns/f8b8d1847392",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "",
            "Gateway": "",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "",
            "IPPrefixLen": 0,
            "IPv6Gateway": "",
            "MacAddress": "",
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": null,
                    "NetworkID": "fd99db2fc2a78f959b1e3b691d4a38125f5e5a2422267c08136d2ad0746e8e35",
                    "EndpointID": "",
                    "Gateway": "",
                    "IPAddress": "172.17.0.2",
                    "IPPrefixLen": 0,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": ""
                }

docker inspect --format '{{.NetworkSettings.IPAddress}}' mylinux
 172.17.0.2

docker exec command  and check the ip address that executes within the container

docker exec -ti mylinux ip add |grep global