摘要:使用Multi-Architecture镜像,可以让docker根据系统架构去拉取对应的镜像,服务的部署脚本等可以在不同架构的系统间使用相同的配置,减化服务配置,提高了服务在不同系统架构间的一致性。

背景

由于Kubernetes集群支持amd64和arm64架构的系统,容器部署时两种类型的节点都可能被集群调度到;所以容器在打包推送到镜像仓库时需要考虑支持多架构,防止调度到不支持的架构节点导致运行失败。

简介

  • Docker register: v2.3.0开始支持Multi-Architecture镜像
  • Docker CLI
    • v1.11开始支持Multi-Architecture镜像拉取
    • v18.03开始支持Multi-Architecture镜像制作

参考资料:

  • Manifest标准:https://docs.docker.com/registry/spec/manifest-v2-1/
  • Manifest命令:https://docs.docker.com/engine/reference/commandline/manifest/
  • Registry:https://github.com/docker/distribution/releases/tag/v2.3.0

制作说明

虽然Multi-Architecture标准很早就有,但是官方的Docker CLI直到v18.03版本才开始支持Multi-Architecture镜像的制作;或者可以考虑使用第三方工具,参考:构建多CPU架构支持的Docker镜像

后续Multi-Architecture镜像的制作使用Docker v18.09版本进行说明。

设置Docker

Docker使用manifest命令来设置MANIFEST_LIST从而支持Multi-Architecture。到Docker v18.09版本为止,manifest命令还是实验性的,所以要配置Docker使能实验性功能。

Docker daemon

修改配置文件/etc/docker/daemon.json,添加配置"experimental": true:

$ sudo cat /etc/docker/daemon.json
[sudo] password for zhangsan:
{
    "data-root": "/home/common/docker",
    "experimental": true,               <- 使能docker daemon实验性功能
    "storage-driver": "overlay2",
    "log-driver": "json-file",
    "log-opts": {
        "max-file": "10",
        "max-size": "100m"
    },
    "insecure-registries": [
        "docker-hub.***.com"
    ]
}

Docker Cli

修改当前用户home目录的配置文件~/.docker/config.json,添加配置"experimental": "enabled":

$ cat ~/.docker/config.json
{
    "experimental": "enabled",          <- 使能docker cli实验性功能
        "proxies":
        {
            "default":
            {
                "httpProxy": "http://127.0.0.1:3128",
                "httpsProxy": "http://127.0.0.1:3128",
                "ftpProxy": "http://127.0.0.1:3128"
            }
        }
}

验证配置

重启docker服务,手工运行docker manifest,出现如下信息说明配置成功:

$ docker manifest
 
Usage:  docker manifest COMMAND

 Manage Docker image manifests and manifest lists

 Commands:
  annotate    Add additional information to a local image manifest
  create      Create a local manifest list for annotating and pushing to a registry
  inspect     Display an image manifest, or manifest list
  push        Push a manifest list to a repository
 
Run 'docker manifest COMMAND --help' for more information on a command.

镜像打包

示例程序stop是一个go程序,启动后暂停不做任何操作,编译到amd64和arm64平台,在amd64平台分别运行如下:

$ ll -hR
.:
total 8.0K
drwxrwxr-x 2 zhangsan zhangsan 4.0K Jun  3 17:21 amd64
drwxrwxr-x 2 zhangsan zhangsan 4.0K Jun  3 17:21 arm64
 
./amd64:
total 240K
-rw-rw-r-- 1 zhangsan zhangsan   51 Jun  3 17:21 Dockerfile
-rwxrwxr-x 1 zhangsan zhangsan 235K Jul 19  2014 stop

./arm64:
total 656K
-rw-rw-r-- 1 zhangsan zhangsan   51 Jun  3 17:21 Dockerfile
-rwxr-xr-x 1 zhangsan zhangsan 651K May 22 14:38 stop

$ amd64/stop
^C%

$ arm64/stop
zsh: exec format error: arm64/stop

使用相同的Dockerfile:

$ cat Dockerfile
FROM scratch

COPY stop /stop
ENTRYPOINT ["/stop"]

amd64版本

$ cd amd64

$ ls
Dockerfile  stop

# 使用tag标注平台信息。
$ docker build -t docker-hub.***.com/zhangsan/stop:1.0-amd64 .
Sending build context to Docker daemon  242.7kB
Step 1/3 : FROM scratch
 --->
Step 2/3 : COPY stop /stop
 ---> ffb0d366bb8c
Step 3/3 : ENTRYPOINT ["/stop"]
 ---> Running in 715d1fbcf450
Removing intermediate container 715d1fbcf450
 ---> 0584fe60ca3d
Successfully built 0584fe60ca3d
Successfully tagged docker-hub.***.com/zhangsan/stop:1.0-amd64

$ docker images | grep stop
REPOSITORY                                        TAG                 IMAGE ID            CREATED             SIZE
docker-hub.***.com/zhangsan/stop        1.0-amd64           0584fe60ca3d        3 seconds ago       240kB

$ docker push docker-hub.***.com/zhangsan/stop:1.0-amd64
The push refers to repository [docker-hub.***.com/zhangsan/stop]
9e352dcc98ab: Pushed
1.0-amd64: digest: sha256:e5b6263b7e45840f139f1bf40b774294712c95df1b43d41598b736f07110341f size: 526

# 可以用manifest的子命令inspect查看镜像的manifest信息,由于是私有仓库,需要使用--insecure参数。
$ docker manifest inspect -v --insecure docker-hub.***.com/zhangsan/stop:1.0-amd64
{
        "Ref": "docker-hub.***.com/zhangsan/stop:1.0-amd64",
        "Descriptor": {
                "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                "digest": "sha256:e5b6263b7e45840f139f1bf40b774294712c95df1b43d41598b736f07110341f",
                "size": 526,
                "platform": {
                        "architecture": "amd64",
                        "os": "linux"
                }
        },
        "SchemaV2Manifest": {
                "schemaVersion": 2,
                "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                "config": {
                        "mediaType": "application/vnd.docker.container.image.v1+json",
                        "size": 1489,
                        "digest": "sha256:0584fe60ca3dbff4c746d376855e89b72b022a4198373b3c8d4c41b97b8b4faf"
                },
                "layers": [
                        {
                                "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
                                "size": 71322,
                                "digest": "sha256:7797d3b3ba41f7abc6a914250f793cf2d69a3e7c0bcc787a596eab4836554552"
                        }
                ]
        }
}

arm64版本

$ cd arm64

$ ls
Dockerfile  stop

$ docker build -t docker-hub.***.com/zhangsan/stop:1.0-arm64 .
Sending build context to Docker daemon  669.2kB
Step 1/3 : FROM scratch
 --->
Step 2/3 : COPY stop /stop
 ---> e02dd9cc9ffa
Step 3/3 : ENTRYPOINT ["/stop"]
 ---> Running in 9b574680691a
Removing intermediate container 9b574680691a
 ---> 1fc97e49b088
Successfully built 1fc97e49b088
Successfully tagged docker-hub.***.com/zhangsan/stop:1.0-arm64

$ docker images | grep stop
docker-hub.***.com/zhangsan/stop        1.0-arm64           1fc97e49b088        8 seconds ago       666kB
docker-hub.***.com/zhangsan/stop        1.0-amd64           0584fe60ca3d        3 minutes ago       240kB

$ docker push docker-hub.***.com/zhangsan/stop:1.0-arm64
The push refers to repository [docker-hub.***.com/zhangsan/stop]
a0c07ccfc4ae: Pushed
1.0-arm64: digest: sha256:089798dc96fcc3d2bf4da3ec4243adcc2507d2ae0c5ba77c5582af626702b3d6 size: 527

# 由于打包镜像的机器是amd64架构,所以arm64的应用镜像中architecture为amd64,后面可以修改,或者直接在arm64机器上打包。
$ docker manifest inspect -v --insecure docker-hub.***.com/zhangsan/stop:1.0-arm64
{
        "Ref": "docker-hub.***.com/zhangsan/stop:1.0-arm64",
        "Descriptor": {
                "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                "digest": "sha256:089798dc96fcc3d2bf4da3ec4243adcc2507d2ae0c5ba77c5582af626702b3d6",
                "size": 527,
                "platform": {
                        "architecture": "amd64",
                        "os": "linux"
                }
        },
        "SchemaV2Manifest": {
                "schemaVersion": 2,
                "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                "config": {
                        "mediaType": "application/vnd.docker.container.image.v1+json",
                        "size": 1488,
                        "digest": "sha256:1fc97e49b0883f59e1e894404785ea1867b9e557d55bdac92f2da09c92b659e7"
                },
                "layers": [
                        {
                                "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
                                "size": 318698,
                                "digest": "sha256:4397808817371da0348eb097ca181996165a9836d629aa1fb97b0d3824ffe2e2"
                        }
                ]
        }
}

验证镜像

$ docker images | grep stop
docker-hub.***.com/zhangsan/stop        1.0-arm64           1fc97e49b088        21 hours ago        666kB
docker-hub.***.com/zhangsan/stop        1.0-amd64           0584fe60ca3d        21 hours ago        240kB

$ docker run docker-hub.***.com/zhangsan/stop:1.0-amd64
^C%

$ docker run docker-hub.***.com/zhangsan/stop:1.0-arm64
standard_init_linux.go:207: exec user process caused "exec format error"

创建MANIFEST_LIST

创建一个MANIFEST_LIST引用之前两个不同平台的镜像。

$ docker manifest inspect -v --insecure docker-hub.***.com/zhangsan/stop:1.0
no such manifest: docker-hub.***.com/zhangsan/stop:1.0

$ docker manifest create --insecure docker-hub.***.com/zhangsan/stop:1.0 docker-hub.***.com/zhangsan/stop:1.0-amd64 docker-hub.***.com/zhangsan/stop:1.0-arm64
Created manifest list docker-hub.***.com/zhangsan/stop:1.0

$ docker manifest inspect -v --insecure docker-hub.***.com/zhangsan/stop:1.0
[
        {
                "Ref": "docker-hub.***.com/zhangsan/stop:1.0-amd64",
                "Descriptor": {
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "digest": "sha256:e5b6263b7e45840f139f1bf40b774294712c95df1b43d41598b736f07110341f",
                        "size": 526,
                        "platform": {
                                "architecture": "amd64",
                                "os": "linux"
                        }
                },
                "SchemaV2Manifest": {
                        "schemaVersion": 2,
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "config": {
                                "mediaType": "application/vnd.docker.container.image.v1+json",
                                "size": 1489,
                                "digest": "sha256:0584fe60ca3dbff4c746d376855e89b72b022a4198373b3c8d4c41b97b8b4faf"
                        },
                        "layers": [
                                {
                                        "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
                                        "size": 71322,
                                        "digest": "sha256:7797d3b3ba41f7abc6a914250f793cf2d69a3e7c0bcc787a596eab4836554552"
                                }
                        ]
                }
        },
        {
                "Ref": "docker-hub.***.com/zhangsan/stop:1.0-arm64",
                "Descriptor": {
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "digest": "sha256:089798dc96fcc3d2bf4da3ec4243adcc2507d2ae0c5ba77c5582af626702b3d6",
                        "size": 527,
                        "platform": {
                                "architecture": "amd64",
                                "os": "linux"
                        }
                },
                "SchemaV2Manifest": {
                        "schemaVersion": 2,
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "config": {
                                "mediaType": "application/vnd.docker.container.image.v1+json",
                                "size": 1488,
                                "digest": "sha256:1fc97e49b0883f59e1e894404785ea1867b9e557d55bdac92f2da09c92b659e7"
                        },
                        "layers": [
                                {
                                        "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
                                        "size": 318698,
                                        "digest": "sha256:4397808817371da0348eb097ca181996165a9836d629aa1fb97b0d3824ffe2e2"
                                }
                        ]
                }
        }
]

修改MANIFEST_LIST

修改刚创建的MANIFEST_LIST,使镜像和架构对应。

$ docker manifest annotate docker-hub.***.com/zhangsan/stop:1.0 docker-hub.***.com/zhangsan/stop:1.0-arm64 --arch arm64
[
        {
                "Ref": "docker-hub.***.com/zhangsan/stop:1.0-amd64",
                "Descriptor": {
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "digest": "sha256:e5b6263b7e45840f139f1bf40b774294712c95df1b43d41598b736f07110341f",
                        "size": 526,
                        "platform": {
                                "architecture": "amd64",
                                "os": "linux"
                        }
                },
                "SchemaV2Manifest": {
                        "schemaVersion": 2,
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "config": {
                                "mediaType": "application/vnd.docker.container.image.v1+json",
                                "size": 1489,
                                "digest": "sha256:0584fe60ca3dbff4c746d376855e89b72b022a4198373b3c8d4c41b97b8b4faf"
                        },
                        "layers": [
                                {
                                        "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
                                        "size": 71322,
                                        "digest": "sha256:7797d3b3ba41f7abc6a914250f793cf2d69a3e7c0bcc787a596eab4836554552"
                                }
                        ]
                }
        },
        {
                "Ref": "docker-hub.***.com/zhangsan/stop:1.0-arm64",
                "Descriptor": {
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "digest": "sha256:089798dc96fcc3d2bf4da3ec4243adcc2507d2ae0c5ba77c5582af626702b3d6",
                        "size": 527,
                        "platform": {
                                "architecture": "arm64",
                                "os": "linux"
                        }
                },
                "SchemaV2Manifest": {
                        "schemaVersion": 2,
                        "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                        "config": {
                                "mediaType": "application/vnd.docker.container.image.v1+json",
                                "size": 1488,
                                "digest": "sha256:1fc97e49b0883f59e1e894404785ea1867b9e557d55bdac92f2da09c92b659e7"
                        },
                        "layers": [
                                {
                                        "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
                                        "size": 318698,
                                        "digest": "sha256:4397808817371da0348eb097ca181996165a9836d629aa1fb97b0d3824ffe2e2"
                                }
                        ]
                }
        }
]

推送MANIFEST_LIST到镜像仓库

创建的MANIFEST_LIST会保存在本地目录~/.docker/manifests,在push时可以使用-p(--purge)参数删除本地数据:

$ ll -R ~/.docker/manifests
/home/zhangsan/.docker/manifests:
total 4
drwxr-xr-x 2 zhangsan zhangsan 4096 Jun  3 17:57 docker-hub.***.com_zhangsan_stop-1.0

/home/zhangsan/.docker/manifests/docker-hub.***.com_zhangsan_stop-1.0:
total 8
-rw-r--r-- 1 zhangsan zhangsan 733 Jun  3 17:57 docker-hub.***.com_zhangsan_stop-1.0-amd64
-rw-r--r-- 1 zhangsan zhangsan 734 Jun  3 18:01 docker-hub.***.com_zhangsan_stop-1.0-arm64

$ sudo docker manifest push -p --insecure docker-hub.***.com/zhangsan/stop:1.0
[sudo] password for zhangsan:
sha256:401767ef0864a65578bef86e3baed2e1e0be905d08d88b57cdeb299850400ece

验证

$ docker images | grep stop
docker-hub.***.com/zhangsan/stop        1.0-arm64           1fc97e49b088        16 hours ago        666kB
docker-hub.***.com/zhangsan/stop        1.0-amd64           0584fe60ca3d        16 hours ago        240kB

# 在amd64架构的系统下拉取不带架构信息的镜像
$ uname -a
Linux SZX1000514415 4.4.0-87-generic #110-Ubuntu SMP Tue Jul 18 12:55:35 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

$ docker pull docker-hub.***.com/zhangsan/stop:1.0
1.0: Pulling from zhangsan/stop
Digest: sha256:401767ef0864a65578bef86e3baed2e1e0be905d08d88b57cdeb299850400ece
Status: Downloaded newer image for docker-hub.***.com/zhangsan/stop:1.0

$ docker images | grep stop
docker-hub.***.com/zhangsan/stop        1.0-arm64           1fc97e49b088        16 hours ago        666kB
docker-hub.***.com/zhangsan/stop        1.0                 0584fe60ca3d        16 hours ago        240kB
docker-hub.***.com/zhangsan/stop        1.0-amd64           0584fe60ca3d        16 hours ago        240kB

# 可正常运行
$ docker run docker-hub.***.com/zhangsan/stop:1.0
^C%

# 在arm64架构的系统下拉取不带架构信息的镜像
[root@kwephicprc09532 ~]# uname -a
Linux kwephicprc09532 4.1.44-06.160.vhulk1711.1.1.aarch64 #1 SMP Tue Oct 16 18:45:06 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux

[root@kwephicprc09532 ~]# docker images | grep stop

[root@kwephicprc09532 ~]# docker pull docker-hub.***.com/zhangsan/stop:1.0
1.0: Pulling from zhangsan/stop
439780881737: Pull complete
Digest: sha256:401767ef0864a65578bef86e3baed2e1e0be905d08d88b57cdeb299850400ece
Status: Downloaded newer image for docker-hub.***.com/zhangsan/stop:1.0

[root@kwephicprc09532 ~]# docker images | grep stop
docker-hub.***.com/zhangsan/stop                          1.0                 1fc97e49b088        16 hours ago        666.5 kB

# 可正常运行
[root@kwephicprc09532 ~]# docker run docker-hub.***.com/zhangsan/stop:1.0
^CShutting down, got signal: Interrupt

升级MANIFEST_LIST

后期升级MANIFEST_LIST方法与创建类似,如:docker-hub.***.com/zhangsan/stop:1.0-amd64镜像升级或docker-hub.***.com/zhangsan/stop:1.0这个MANIFEST_LIST要关联其它镜像时,都需要升级MANIFEST_LIST。需要注意几点:

  • manifest create时使用参数-a(--amend)
  • 升级后没有关联到期望的镜像可以先手工删除本地保存的manifest再尝试

使用Multi-Architecture镜像的好处

使用Multi-Architecture镜像,可以让docker根据系统架构去拉取对应的镜像,服务的部署脚本等可以在不同架构的系统间使用相同的配置,减化服务配置,提高了服务在不同系统架构间的一致性。

本文分享自华为云社区《叮!快收好这份Multi-Architecture镜像制作指南》,原文作者:Thirteenmans 。

 

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