The inspect command is used in combination with the container ID. This means we first have to get the container ID, one way of getting the container ID is using the "docker ps" command as shown below:
[root@localhost etc]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 0a52831c65e8 oracle/nosql "java -jar lib/kvstor" 11 hours ago Up 11 hours 5000-5001/tcp, 5010-5020/tcp nosql_node_0 [root@localhost etc]#
If we want to know more about the container running, and identified with container ID 0a52831c65e8 wen can execute the "docker inspect" command to retrieve the JSON response as shown in the example below:
[root@localhost etc]# docker inspect 0a52831c65e8
[
{
"Id": "0a52831c65e86727b248bc66c2cb5e4be037f85473a6c0645f8b81c5f2381e4f",
"Created": "2017-07-10T19:43:49.205922395Z",
"Path": "java",
"Args": [
"-jar",
"lib/kvstore.jar",
"kvlite",
"-secure-config",
"disable",
"-root",
"/kvroot"
],
"State": {
"Status": "running",
"Running": true,
"Paused": false,
"Restarting": false,
"OOMKilled": false,
"Dead": false,
"Pid": 5364,
"ExitCode": 0,
"Error": "",
"StartedAt": "2017-07-10T19:43:49.636183576Z",
"FinishedAt": "0001-01-01T00:00:00Z"
},
"Image": "sha256:247be918b211e6690ad33463336e502c260b1a35010102d93967bd49dc061e46",
"ResolvConfPath": "/var/lib/docker/containers/0a52831c65e86727b248bc66c2cb5e4be037f85473a6c0645f8b81c5f2381e4f/resolv.conf",
"HostnamePath": "/var/lib/docker/containers/0a52831c65e86727b248bc66c2cb5e4be037f85473a6c0645f8b81c5f2381e4f/hostname",
"HostsPath": "/var/lib/docker/containers/0a52831c65e86727b248bc66c2cb5e4be037f85473a6c0645f8b81c5f2381e4f/hosts",
"LogPath": "/var/lib/docker/containers/0a52831c65e86727b248bc66c2cb5e4be037f85473a6c0645f8b81c5f2381e4f/0a52831c65e86727b248bc66c2cb5e4be037f85473a6c0645f8b81c5f2381e4f-json.log",
"Name": "/nosql_node_0",
"RestartCount": 0,
"Driver": "devicemapper",
"MountLabel": "",
"ProcessLabel": "",
"AppArmorProfile": "",
"ExecIDs": null,
"HostConfig": {
"Binds": null,
"ContainerIDFile": "",
"LogConfig": {
"Type": "json-file",
"Config": {}
},
"NetworkMode": "default",
"PortBindings": {},
"RestartPolicy": {
"Name": "no",
"MaximumRetryCount": 0
},
"AutoRemove": false,
"VolumeDriver": "",
"VolumesFrom": null,
"CapAdd": null,
"CapDrop": null,
"Dns": [],
"DnsOptions": [],
"DnsSearch": [],
"ExtraHosts": null,
"GroupAdd": null,
"IpcMode": "",
"Cgroup": "",
"Links": null,
"OomScoreAdj": 0,
"PidMode": "",
"Privileged": false,
"PublishAllPorts": false,
"ReadonlyRootfs": false,
"SecurityOpt": null,
"UTSMode": "",
"UsernsMode": "",
"ShmSize": 67108864,
"Runtime": "runc",
"ConsoleSize": [
0,
0
],
"Isolation": "",
"CpuShares": 0,
"Memory": 0,
"CgroupParent": "",
"BlkioWeight": 0,
"BlkioWeightDevice": null,
"BlkioDeviceReadBps": null,
"BlkioDeviceWriteBps": null,
"BlkioDeviceReadIOps": null,
"BlkioDeviceWriteIOps": null,
"CpuPeriod": 0,
"CpuQuota": 0,
"CpusetCpus": "",
"CpusetMems": "",
"Devices": [],
"DiskQuota": 0,
"KernelMemory": 0,
"MemoryReservation": 0,
"MemorySwap": 0,
"MemorySwappiness": -1,
"OomKillDisable": false,
"PidsLimit": 0,
"Ulimits": null,
"CpuCount": 0,
"CpuPercent": 0,
"IOMaximumIOps": 0,
"IOMaximumBandwidth": 0
},
"GraphDriver": {
"Name": "devicemapper",
"Data": {
"DeviceId": "34",
"DeviceName": "docker-251:1-1835143-986c026ad2d7e69cae96df9d46f1d15c23c88103f7dc7d7756a8be2f50f474ea",
"DeviceSize": "10737418240"
}
},
"Mounts": [
{
"Name": "a37d7c33e0d78922160c4b411f13350e9692dddf26cdea794a5dd6f266723175",
"Source": "/var/lib/docker/volumes/a37d7c33e0d78922160c4b411f13350e9692dddf26cdea794a5dd6f266723175/_data",
"Destination": "/kvroot",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
}
],
"Config": {
"Hostname": "0a52831c65e8",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"ExposedPorts": {
"5000/tcp": {},
"5001/tcp": {},
"5010/tcp": {},
"5011/tcp": {},
"5012/tcp": {},
"5013/tcp": {},
"5014/tcp": {},
"5015/tcp": {},
"5016/tcp": {},
"5017/tcp": {},
"5018/tcp": {},
"5019/tcp": {},
"5020/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"JAVA_HOME=/usr/lib/jvm/java-openjdk",
"VERSION=4.3.11",
"KVHOME=/kv-4.3.11",
"PACKAGE=kv-ce",
"EXTENSION=zip",
"BASE_URL=http://download.oracle.com/otn-pub/otn_software/nosql-database/",
"_JAVA_OPTIONS=-Djava.security.egd=file:/dev/./urandom"
],
"Cmd": [
"java",
"-jar",
"lib/kvstore.jar",
"kvlite",
"-secure-config",
"disable",
"-root",
"/kvroot"
],
"Image": "oracle/nosql",
"Volumes": {
"/kvroot": {}
},
"WorkingDir": "/kv-4.3.11",
"Entrypoint": null,
"OnBuild": null,
"Labels": {}
},
"NetworkSettings": {
"Bridge": "",
"SandboxID": "3f3505304a821da97a668ae622a09738cf8c88768e77f5c1995154f431461700",
"HairpinMode": false,
"LinkLocalIPv6Address": "",
"LinkLocalIPv6PrefixLen": 0,
"Ports": {
"5000/tcp": null,
"5001/tcp": null,
"5010/tcp": null,
"5011/tcp": null,
"5012/tcp": null,
"5013/tcp": null,
"5014/tcp": null,
"5015/tcp": null,
"5016/tcp": null,
"5017/tcp": null,
"5018/tcp": null,
"5019/tcp": null,
"5020/tcp": null
},
"SandboxKey": "/var/run/docker/netns/3f3505304a82",
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
"EndpointID": "28368b7c9058e300d08cc3a3453568cb903504ed33b4c61c6349963ad190160f",
"Gateway": "172.17.0.1",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "172.17.0.2",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"MacAddress": "02:42:ac:11:00:02",
"Networks": {
"bridge": {
"IPAMConfig": null,
"Links": null,
"Aliases": null,
"NetworkID": "fc7e96b764adee7ae2a6f061b766c61ea82ec7754faa64f2483889fa0a5a3a5f",
"EndpointID": "28368b7c9058e300d08cc3a3453568cb903504ed33b4c61c6349963ad190160f",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.2",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:11:00:02"
}
}
}
}
]
[root@localhost etc]#
As you can see above the "docker inspect" command provides a very rich set of information whcih can be used for a variaty of things. However, in our example case we only wanted to know the IP address which has been assigned to the container. This means we will have to extract the IP from the JSON response. The below comman will help you in extracting just that from the larger set of information:
[root@localhost etc]# docker inspect 0a52831c65e8 | grep IPAddress | cut -d '"' -f 4| sort -r | head -1 172.17.0.2 [root@localhost etc]#
The above example could be the starting point of a bash function in a wider script which allows you to simply call a function in combination with a variable for the container ID and return the IP information you need. Knowing and understanding how to quickly extract the IP information from the inspect command can help you in building scripting arround docker.
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