一文讲解如何获取k8s容器里运行的jar包

目录

• 01 引言
• 02 从镜像信息获取
• 03 进入容器获取（推荐）
• 04 文末

01 引言

在k8s上运行了第三方的应用，很多时候我们都想知道运行流程，一般都会从k8s容器中获取jar包。

那么该如何把里面的jar包提取出来呢？

其实有两种方式，分别为：

① 从镜像信息获取；

② 进入容器获取

02 从镜像信息获取

主要参考了：https://www.jb51.net/article/264058.htm

首先，查看镜像：

docker image ls |grep 你想要找到镜像名

查看镜像内容：

docker inspect 镜像ID

内容大概如下：

[
    {
        "Id": "sha256:bd95813096bd754b657fb7e531e3b86075ccf4388df5b452a819919ff00c91c2",
        "RepoTags": [
            "vvp-gateway:2.6.3_simon"
        ],
        "RepoDigests": [],
        "Parent": "sha256:59250f7815884db8ace5b956946370e8924ac74ad12acb922eb4431ad477418c",
        "Comment": "",
        "Created": "2022-07-11T07:12:46.084025129Z",
        "Container": "cfca40ed3f7bb18674c6a2fcf0f78267517de6268c6d6bfddfc8c380fb33818d",
        "ContainerConfig": {
            "Hostname": "cfca40ed3f7b",
            "Domainname": "",
            "User": "root",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "ExposedPorts": {
                "8080/tcp": {}
            },
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/openjdk-11/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "JAVA_HOME=/usr/local/openjdk-11",
                "LANG=C.UTF-8",
                "JAVA_VERSION=11.0.15"
            ],
            "Cmd": [
                "/bin/sh",
                "-c",
                "#(nop) ",
                "CMD [\"java\" \"-Xdebug\" \"-agentlib:jdwp=transport=dt_socket,server=y,address=0.0.0.0:8899,suspend=n\" \"-XX:MaxRAMPercentage=50.0\" \"-XX:MaxMetaspaceSize=256m\" \"-Djava.security.egd=file:/dev/./urandom\" \"-cp\" \"/vvp/app:/vvp/app/lib/*\" \"com.ververica.platform.gateway.GatewayApplication\"]"
            ],
            "Image": "sha256:59250f7815884db8ace5b956946370e8924ac74ad12acb922eb4431ad477418c",
            "Volumes": {
                "/vvp/data": {},
                "/vvp/etc": {},
                "/vvp/secrets": {}
            },
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "maintainer": "Ververica <platform@ververica.com>"
            }
        },
        "DockerVersion": "20.10.5",
        "Author": "",
        "Config": {
            "Hostname": "",
            "Domainname": "",
            "User": "root",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "ExposedPorts": {
                "8080/tcp": {}
            },
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/openjdk-11/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "JAVA_HOME=/usr/local/openjdk-11",
                "LANG=C.UTF-8",
                "JAVA_VERSION=11.0.15"
            ],
            "Cmd": [
                "java",
                "-Xdebug",
                "-agentlib:jdwp=transport=dt_socket,server=y,address=0.0.0.0:8899,suspend=n",
                "-XX:MaxRAMPercentage=50.0",
                "-XX:MaxMetaspaceSize=256m",
                "-Djava.security.egd=file:/dev/./urandom",
                "-cp",
                "/vvp/app:/vvp/app/lib/*",
                "com.ververica.platform.gateway.GatewayApplication"
            ],
            "Image": "sha256:59250f7815884db8ace5b956946370e8924ac74ad12acb922eb4431ad477418c",
            "Volumes": {
                "/vvp/data": {},
                "/vvp/etc": {},
                "/vvp/secrets": {}
            },
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "maintainer": "Ververica <platform@ververica.com>"
            }
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 919299037,
        "VirtualSize": 919299037,
        "GraphDriver": {
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/cc946e03217e4171399be855e56505bb037276d062c2829beea93d77f43cfaf6/diff:/var/lib/docker/overlay2/6b0a352106f128579123a45e3991b9f2492994d435180b3ca630b022f7cde088/diff:/var/lib/docker/overlay2/29ccfa6c76844dc9f104eabbf2c0e4db32a040ebfa3691078f9e751ea5a7d891/diff:/var/lib/docker/overlay2/d3eda21c53fad143abc5981dfccfac0ed33f5a2e71d3a78d9ca22ea3a6243c89/diff:/var/lib/docker/overlay2/6f336ec260b8060e77e268412246b8ecbf8a3ccbe025422dacf341337228793e/diff:/var/lib/docker/overlay2/d73a8b39b5bb63ba313669bab84d6a15378bd327944e4a43519fb8080b6e2fab/diff:/var/lib/docker/overlay2/568f3a48847e451e5482ffa75b65eff42d46b6eabe20371529379dcc79d528fb/diff:/var/lib/docker/overlay2/85feabbee50004762db71400d79ee1213b6bd580a949f628c765f3c29f7b5dd3/diff:/var/lib/docker/overlay2/76336ac57ecea887d8e5743c5897618a6398a609f9936ae7be811a2c45aad847/diff:/var/lib/docker/overlay2/db8d96c0e03b7632ee96077360103a053b88a04c95323ea6b8d612ecc918b78e/diff:/var/lib/docker/overlay2/41c62e7cf81c95bc8b77e6ce2677ded8448722b1fdb72ff9db395db7537fce8c/diff:/var/lib/docker/overlay2/35b917ac3d4b14291f8459e2ca01da3d016750b0586d7d1e412034340fe0f686/diff:/var/lib/docker/overlay2/769a1d6b4fd308283f55d7dea89c0bf375997560f85115a167b7528d26c3f256/diff:/var/lib/docker/overlay2/d8d20b6d384247cc05a7e1c1c4b0011f580ff0f01b0c1a0506420d7497dae89c/diff",
                "MergedDir": "/var/lib/docker/overlay2/8a1defde1405c4ad9ee22830f3dac0bab42a492cbb55109364f3e968db3eab30/merged",
                "UpperDir": "/var/lib/docker/overlay2/8a1defde1405c4ad9ee22830f3dac0bab42a492cbb55109364f3e968db3eab30/diff",
                "WorkDir": "/var/lib/docker/overlay2/8a1defde1405c4ad9ee22830f3dac0bab42a492cbb55109364f3e968db3eab30/work"
            },
            "Name": "overlay2"
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:9c1b6dd6c1e6be9fdd2b1987783824670d3b0dd7ae8ad6f57dc3cea5739ac71e",
                "sha256:13a34b6fff7804cf7f6e8f52a4cf25ceb2e32fc35a6f39e8158074c64831ebf0",
                "sha256:8da60230c8c21a305a0b1871ea654b3a68ace50520397bd46b8b647c6e0891c4",
                "sha256:f93bb772c4958617a803266969a338094cb73511c18605d87f53b1b2cfadc7b0",
                "sha256:af70cff76a6274cc87e5a2f1c6c1fc6554524adf407fa94e387292d91b808d39",
                "sha256:4503e1661bd9fe4381f37dd8c9960ef4301f387c88e6d1582922cccd0544d03e",
                "sha256:690041a64b809a889f8e5e2ec9eda4300fbf76dfd488b8ee334eea3ced9ac7a3",
                "sha256:f346876b3ef523394c2d0473501a50392d1df530daf0bd70d351830c782ccba3",
                "sha256:620e3c5d227e2b96f1205ead77b84be11b239adf387d7b7e83c6cd4a508431aa",
                "sha256:9b33a349b1c75a9040b5a8e277c0e0a535a87ba6fa87861268280f9862f8803d",
                "sha256:6f55434bbaa3b9d42d629ce6ac1c0eba4214b835cdb7b3c5c74deae69a5c5436",
                "sha256:8a9739c65869fd51708ba2ab262469b6b6d54f9576a924c89a852c26e8125c7b",
                "sha256:cfe58338cf6bc3ed59ab76b731315e9d47ab96e8b8f4c84a501ce709e18930e0",
                "sha256:57e0cc2daa9243c201289f7c677c40e1f45bc2f17023795ef7a8ef45f147d796",
                "sha256:095b3833d28e6e3049512b7c588025cdb34fbf08c0de67cbd8e818714ab5b4c5"
            ]
        },
        "Metadata": {
            "LastTagTime": "2022-07-11T15:12:46.143347824+08:00"
        }
    }
]

从内容中，可以看到打包镜像的流程，其中Cmd的标签，可以看出使用java来执行程序，依赖库及执行程序入口如下：

一般jar包在UpperDir：

进入对应的路径：

cd /var/lib/docker/overlay2/8a1defde1405c4ad9ee22830f3dac0bab42a492cbb55109364f3e968db3eab30/diff

可以看到里面有对应的文件及jar包，如果还没有，只能进入容器查看了。

03 进入容器获取（推荐）

进入容器命令：

kubectl exec -it pod名称 -n命名空间 bash

注意到了以上的提示，默认进入“appmanager”容器，实际我们希望进入的容器是gateway，所以需要指定容器进入：

kubectl exec -it pod名称 -n命名空间 -c容器名 bash

看看里面有什么内容：

进入目录：

可以看到此目录已经含有所有程序运行时需要的内容了。

04 文末

文本主要讲解了使用两种方式去获取容器中运行的jar包

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