### 歡迎訪問我的GitHub
> 這裡分類和彙總了欣宸的全部原創(含配套原始碼)：[https://github.com/zq2599/blog_demos](https://github.com/zq2599/blog_demos)

- 對於執行在Docker環境的容器，有時我們想查詢它們的一些基本資訊，例如環境變數、hostname、ip地址等，接下來我們以一個tomcat容器為例，看看有哪些方式來取得這些資訊；

### 建立tomcat容器
- 在docker環境下執行如下命令，即可建立一個名為tomcat001的tomcat容器：
```shell
docker run --name tomcat001 -idt tomcat
```
- 執行docker ps檢查一下，容器建立成功：
```shell
root@maven:~# docker ps
CONTAINER ID    IMAGE   COMMAND             CREATED         STATUS          PORTS       NAMES
98d119ed4c73    tomcat  "catalina.sh run"   10 minutes ago  Up 10 minutes   8080/tcp    tomcat001
```

- 獲取資訊常用的方式有如下三種：
1. 進入容器內部獲取資訊；
2. 執行docker exec命令；
3. 執行docker inspect -f命令**（推薦方式）**；
### 第一種：進入容器內部獲取資訊
- 執行以下命令可進入容器內部：
```shell
docker exec -it tomcat001 /bin/bash
```
- 此時已進入容器內部，所以分別執行**hostname、ip addr、env**這三個命令可以獲取相關資訊，如下：
```shell
root@98d119ed4c73:/usr/local/tomcat# hostname
98d119ed4c73
root@98d119ed4c73:/usr/local/tomcat# ip addr
1: lo: <loopback> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
17: eth0@if18: <broadcast> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:ac:11:00:05 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 172.17.0.5/16 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:acff:fe11:5/64 scope link 
       valid_lft forever preferred_lft forever
root@98d119ed4c73:/usr/local/tomcat# env
LD_LIBRARY_PATH=/usr/local/tomcat/native-jni-lib
CATALINA_HOME=/usr/local/tomcat
LANG=C.UTF-8
HOSTNAME=98d119ed4c73
OPENSSL_VERSION=1.1.0f-3+deb9u1
TOMCAT_VERSION=8.5.24
GPG_KEYS=05AB33110949707C93A279E3D3EFE6B686867BA6 07E48665A34DCAFAE522E5E6266191C37C037D42 47309207D818FFD8DCD3F83F1931D684307A10A5 541FBE7D8F78B25E055DDEE13C370389288584E7 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 713DA88BE50911535FE716F5208B0AB1D63011C7 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23
JAVA_HOME=/docker-java-home/jre
TOMCAT_NATIVE_LIBDIR=/usr/local/tomcat/native-jni-lib
JAVA_VERSION=8u151
PWD=/usr/local/tomcat
HOME=/root
CA_CERTIFICATES_JAVA_VERSION=20170531+nmu1
TOMCAT_MAJOR=8
JAVA_DEBIAN_VERSION=8u151-b12-1~deb9u1
TOMCAT_SHA1=9e26ba61c5665aafc849073edeb769be555283cd
TERM=xterm
SHLVL=1
TOMCAT_ASC_URLS=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc      https://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc    https://www.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc       https://archive.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc
PATH=/usr/local/tomcat/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
TOMCAT_TGZ_URLS=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz  https://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz        https://www.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz   https://archive.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz
_=/usr/bin/env
```

### 第二種：執行docker exec命令
- 不用進入容器，直接在docker環境執行**docker exec 容器名 容器內命令**的方式也可以獲取相關資訊，舉例如下：
1. 獲取容器的hostname：docker exec tomcat001 hostname
2. 獲取容器ip地址：docker exec tomcat001 ip addr
3. 獲取容器環境變數：docker exec tomcat001 env

- 執行結果如下所示:
```shell
root@maven:~# docker exec tomcat001 hostname
98d119ed4c73
root@maven:~# docker exec tomcat001 ip addr
1: lo: <loopback> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
17: eth0@if18: <broadcast> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:ac:11:00:05 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 172.17.0.5/16 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:acff:fe11:5/64 scope link 
       valid_lft forever preferred_lft forever
root@maven:~# docker exec tomcat001 env
PATH=/usr/local/tomcat/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=98d119ed4c73
LANG=C.UTF-8
JAVA_HOME=/docker-java-home/jre
JAVA_VERSION=8u151
JAVA_DEBIAN_VERSION=8u151-b12-1~deb9u1
CA_CERTIFICATES_JAVA_VERSION=20170531+nmu1
CATALINA_HOME=/usr/local/tomcat
TOMCAT_NATIVE_LIBDIR=/usr/local/tomcat/native-jni-lib
LD_LIBRARY_PATH=/usr/local/tomcat/native-jni-lib
OPENSSL_VERSION=1.1.0f-3+deb9u1
GPG_KEYS=05AB33110949707C93A279E3D3EFE6B686867BA6 07E48665A34DCAFAE522E5E6266191C37C037D42 47309207D818FFD8DCD3F83F1931D684307A10A5 541FBE7D8F78B25E055DDEE13C370389288584E7 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 713DA88BE50911535FE716F5208B0AB1D63011C7 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23
TOMCAT_MAJOR=8
TOMCAT_VERSION=8.5.24
TOMCAT_SHA1=9e26ba61c5665aafc849073edeb769be555283cd
TOMCAT_TGZ_URLS=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz  https://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz        https://www.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz   https://archive.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz
TOMCAT_ASC_URLS=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc      https://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc    https://www.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc       https://archive.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc
HOME=/root
```

### 第三種：使用docker inspect命令
- 推薦使用**docker inspect**來獲取資訊，這個命令會返回一個json字串，裡面以key-value的格式準備了該容器相關的資訊，內容十分豐富，可以一次性取得全部內容，也可以返回指定key對應的資訊；

- 我們先來看看所有內容，執行命令**docker inspect tomcat001**，可以看到如下資訊：
```shell
root@maven:~# docker inspect tomcat001
[
    {
        "Id": "98d119ed4c73c750e53353e77f7c6942803809a9d5dedc28d8b0f41ce58b8b17",
        "Created": "2018-05-06T07:39:45.464492435Z",
        "Path": "catalina.sh",
        "Args": [
            "run"
        ],
        "State": {
            "Status": "running",
            "Running": true,
            "Paused": false,
            "Restarting": false,
            "OOMKilled": false,
            "Dead": false,
            "Pid": 22468,
            "ExitCode": 0,
            "Error": "",
            "StartedAt": "2018-05-06T07:39:46.143092505Z",
            "FinishedAt": "0001-01-01T00:00:00Z"
        },
        "Image": "sha256:3dcfe809147daf54fbdbe1f6886b4c49df63f28e2b3c8ac119fef6a7f7490d3c",
        "ResolvConfPath": "/var/lib/docker/containers/98d119ed4c73c750e53353e77f7c6942803809a9d5dedc28d8b0f41ce58b8b17/resolv.conf",
        "HostnamePath": "/var/lib/docker/containers/98d119ed4c73c750e53353e77f7c6942803809a9d5dedc28d8b0f41ce58b8b17/hostname",
        "HostsPath": "/var/lib/docker/containers/98d119ed4c73c750e53353e77f7c6942803809a9d5dedc28d8b0f41ce58b8b17/hosts",
        "LogPath": "/var/lib/docker/containers/98d119ed4c73c750e53353e77f7c6942803809a9d5dedc28d8b0f41ce58b8b17/98d119ed4c73c750e53353e77f7c6942803809a9d5dedc28d8b0f41ce58b8b17-json.log",
        "Name": "/tomcat001",
        "RestartCount": 0,
        "Driver": "aufs",
        "MountLabel": "",
        "ProcessLabel": "",
        "AppArmorProfile": "",
        "ExecIDs": [
            "cffec99f38514024f6a6e31e0e160d37d295041e4813a2245466be2dbc9c4037"
        ],
        "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,
            "NanoCpus": 0,
            "CgroupParent": "",
            "BlkioWeight": 0,
            "BlkioWeightDevice": null,
            "BlkioDeviceReadBps": null,
            "BlkioDeviceWriteBps": null,
            "BlkioDeviceReadIOps": null,
            "BlkioDeviceWriteIOps": null,
            "CpuPeriod": 0,
            "CpuQuota": 0,
            "CpuRealtimePeriod": 0,
            "CpuRealtimeRuntime": 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": "aufs",
            "Data": null
        },
        "Mounts": [],
        "Config": {
            "Hostname": "98d119ed4c73",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "ExposedPorts": {
                "8080/tcp": {}
            },
            "Tty": true,
            "OpenStdin": true,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/tomcat/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "LANG=C.UTF-8",
                "JAVA_HOME=/docker-java-home/jre",
                "JAVA_VERSION=8u151",
                "JAVA_DEBIAN_VERSION=8u151-b12-1~deb9u1",
                "CA_CERTIFICATES_JAVA_VERSION=20170531+nmu1",
                "CATALINA_HOME=/usr/local/tomcat",
                "TOMCAT_NATIVE_LIBDIR=/usr/local/tomcat/native-jni-lib",
                "LD_LIBRARY_PATH=/usr/local/tomcat/native-jni-lib",
                "OPENSSL_VERSION=1.1.0f-3+deb9u1",
                "GPG_KEYS=05AB33110949707C93A279E3D3EFE6B686867BA6 07E48665A34DCAFAE522E5E6266191C37C037D42 47309207D818FFD8DCD3F83F1931D684307A10A5 541FBE7D8F78B25E055DDEE13C370389288584E7 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 713DA88BE50911535FE716F5208B0AB1D63011C7 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23",
                "TOMCAT_MAJOR=8",
                "TOMCAT_VERSION=8.5.24",
                "TOMCAT_SHA1=9e26ba61c5665aafc849073edeb769be555283cd",
                "TOMCAT_TGZ_URLS=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz \thttps://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz \thttps://www.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz \thttps://archive.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz",
                "TOMCAT_ASC_URLS=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc \thttps://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc \thttps://www.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc \thttps://archive.apache.org/dist/tomcat/tomcat-8/v8.5.24/bin/apache-tomcat-8.5.24.tar.gz.asc"
            ],
            "Cmd": [
                "catalina.sh",
                "run"
            ],
            "ArgsEscaped": true,
            "Image": "tomcat",
            "Volumes": null,
            "WorkingDir": "/usr/local/tomcat",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {}
        },
        "NetworkSettings": {
            "Bridge": "",
            "SandboxID": "50244517221e6faff4217ff5453919f0c297b10434812ecfbf3decb3ce9860f6",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": {
                "8080/tcp": null
            },
            "SandboxKey": "/var/run/docker/netns/50244517221e",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "e9336feece03b1c87e6724253575ee50963e9bdc1f9618609fe641a8a939b87a",
            "Gateway": "172.17.0.1",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "172.17.0.5",
            "IPPrefixLen": 16,
            "IPv6Gateway": "",
            "MacAddress": "02:42:ac:11:00:05",
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": null,
                    "NetworkID": "87eb4d08d408c08489db4460915aabed59210d04f8193364420d3719cd308d83",
                    "EndpointID": "e9336feece03b1c87e6724253575ee50963e9bdc1f9618609fe641a8a939b87a",
                    "Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.5",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:11:00:05"
                }
            }
        }
    }
]
```
- 可見內容十分豐富；

- 如果我們只對其中的一些感興趣，例如hostname、ip地址、環境變數，該如何檢視呢？
- hostname：在返回值中，hostname的位置如下圖紅框所示，
![image.png](https://bbs-img.huaweicloud.com/blogs/img/20220525/1653433253867812030.png)

由上圖可見，hostname位於Config.Hostname這個節點位置，所以執行命令**docker inspect -f {{.Config.Hostname}} tomcat001**即可獲取到hostname，如下所示：
```shell
root@maven:~# docker inspect -f {{.Config.Hostname}} tomcat001
98d119ed4c73
```
- ip地址：執行命令**docker inspect -f {{.NetworkSettings.IPAddress}} tomcat001**即可獲取到ip地址：
```shell
root@maven:~# docker inspect -f {{.NetworkSettings.IPAddress}} tomcat001
172.17.0.5
```
- 環境變數：從完整的inspect資訊中可以看到環境變數Config.Env的內容是個json陣列，所以除了用**docker inspect -f {{.Config.Env}} tomcat001**獲取所有環境變數資訊，還可以用**docker inspect -f '{{index .Config.Env 1}}' tomcat001**命令獲取陣列中的某一條記錄，如下：
```shell
root@maven:~# docker inspect -f '{{index .Config.Env 1}}' tomcat001
LANG=C.UTF-8
root@maven:~# docker inspect -f '{{index .Config.Env 2}}' tomcat001 
JAVA_HOME=/docker-java-home/jre
```

- 至此，三種獲取容器資訊的方式已經全部列出，之所以在本文中推薦第三種，是因為有時我們會在shell指令碼中獲取容器資訊，這時候用這種方式最為簡單；

### 歡迎關注ITpub：程式設計師欣宸
> [學習路上，你不孤單，欣宸原創一路相伴...](http://blog.itpub.net/70017844/)</broadcast></loopback></broadcast></loopback>

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