Docker學習入門之——構建本身的鏡像

安裝基本docker的基礎環境

root@managert:~ # yum list|grep docker

cockpit-docker.x86_64                   0.114-2.el7.centos             extras   
docker.x86_64                           1.10.3-46.el7.centos.14        extras   
docker-common.x86_64                    1.10.3-46.el7.centos.14        extras   
docker-devel.x86_64                     1.3.2-4.el7.centos             extras   
docker-distribution.x86_64              2.4.1-2.el7                    extras   
docker-forward-journald.x86_64          1.10.3-44.el7.centos           extras   
docker-latest.x86_64                    1.12.1-2.el7.centos            extras   
docker-latest-logrotate.x86_64          1.12.1-2.el7.centos            extras   
docker-latest-v1.10-migrator.x86_64     1.12.1-2.el7.centos            extras   
docker-logrotate.x86_64                 1.10.3-46.el7.centos.14        extras   
docker-lvm-plugin.x86_64                1.10.3-46.el7.centos.14        extras   
docker-novolume-plugin.x86_64           1.10.3-46.el7.centos.14        extras   
docker-python.x86_64                    1.4.0-115.el7                  extras   
docker-registry.noarch                  0.6.8-8.el7                    extras   
docker-registry.x86_64                  0.9.1-7.el7                    extras   
docker-selinux.x86_64                   1.10.3-46.el7.centos.14        extras   
docker-unit-test.x86_64                 1.10.3-46.el7.centos.14        extras   
docker-v1.10-migrator.x86_64            1.10.3-46.el7.centos.14        extras

root@managert:~ # yum install -y docker docker-engine #執行安裝

安裝教程能夠參見官方站點

安裝完成後能夠經過docker version查看安裝狀態

root@managert:~ # docker version            
Client:
 Version:      1.12.3
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   6b644ec
 Built:        
 OS/Arch:      linux/amd64

Server:
 Version:      1.12.3
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   6b644ec
 Built:        
 OS/Arch:      linux/amd64

建立基本鏡像（基於centos）

如下腳本是在centos上建立基於centos的鏡像的腳本，copy後執行

#!/usr/bin/env bash
#
# Create a base CentOS Docker image.
#
# This script is useful on systems with yum installed (e.g., building
# a CentOS image on CentOS).  See contrib/mkimage-rinse.sh for a way
# to build CentOS images on other systems.

set -e

usage() {
   cat <<EOOPTS
$(basename $0) [OPTIONS] <name>
OPTIONS:
 -p "<packages>"  The list of packages to install in the container.
                  The default is blank.
 -g "<groups>"    The groups of packages to install in the container.
                  The default is "Core".
 -y <yumconf>     The path to the yum config to install packages from. The
                  default is /etc/yum.conf for Centos/RHEL and /etc/dnf/dnf.conf for Fedora
EOOPTS
   exit 1
}

# option defaults
yum_config=/etc/yum.conf
if [ -f /etc/dnf/dnf.conf ] && command -v dnf &> /dev/null; then
	yum_config=/etc/dnf/dnf.conf
	alias yum=dnf
fi
install_groups="Core"
while getopts ":y:p:g:h" opt; do
   case $opt in
       y)
           yum_config=$OPTARG
           ;;
       h)
           usage
           ;;
       p)
           install_packages="$OPTARG"
           ;;
       g)
           install_groups="$OPTARG"
           ;;
       \?)
           echo "Invalid option: -$OPTARG"
           usage
           ;;
   esac
done
shift $((OPTIND - 1))
name=$1
if [[ -z $name ]]; then
   usage
fi
target=$(mktemp -d --tmpdir $(basename $0).XXXXXX)
set -x
mkdir -m 755 "$target"/dev
mknod -m 600 "$target"/dev/console c 5 1
mknod -m 600 "$target"/dev/initctl p
mknod -m 666 "$target"/dev/full c 1 7
mknod -m 666 "$target"/dev/null c 1 3
mknod -m 666 "$target"/dev/ptmx c 5 2
mknod -m 666 "$target"/dev/random c 1 8
mknod -m 666 "$target"/dev/tty c 5 0
mknod -m 666 "$target"/dev/tty0 c 4 0
mknod -m 666 "$target"/dev/urandom c 1 9
mknod -m 666 "$target"/dev/zero c 1 5

# amazon linux yum will fail without vars set
if [ -d /etc/yum/vars ]; then
	mkdir -p -m 755 "$target"/etc/yum
	cp -a /etc/yum/vars "$target"/etc/yum/
fi

if [[ -n "$install_groups" ]];
then
   yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
       --setopt=group_package_types=mandatory -y groupinstall $install_groups
fi

if [[ -n "$install_packages" ]];
then
   yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
       --setopt=group_package_types=mandatory -y install $install_packages
fi

yum -c "$yum_config" --installroot="$target" -y clean all

cat > "$target"/etc/sysconfig/network <<EOF
NETWORKING=yes
HOSTNAME=localhost.localdomain
EOF

# effectively: febootstrap-minimize --keep-zoneinfo --keep-rpmdb --keep-services "$target".
#  locales
rm -rf "$target"/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}
#  docs and man pages
rm -rf "$target"/usr/share/{man,doc,info,gnome/help}
#  cracklib
rm -rf "$target"/usr/share/cracklib
#  i18n
rm -rf "$target"/usr/share/i18n
#  yum cache
rm -rf "$target"/var/cache/yum
mkdir -p --mode=0755 "$target"/var/cache/yum
#  sln
rm -rf "$target"/sbin/sln
#  ldconfig
rm -rf "$target"/etc/ld.so.cache "$target"/var/cache/ldconfig
mkdir -p --mode=0755 "$target"/var/cache/ldconfig
version=
for file in "$target"/etc/{redhat,system}-release
do
   if [ -r "$file" ]; then
       version="$(sed 's/^[^0-9\]*\([0-9.]\+\).*$/\1/' "$file")"
       break
   fi
done
if [ -z "$version" ]; then
   echo >&2 "warning: cannot autodetect OS version, using '$name' as tag"
   version=$name
fi
tar --numeric-owner -c -C "$target" . | docker import - $name:$version
docker run -i -t --rm $name:$version /bin/bash -c 'echo success'
rm -rf "$target"

執行後看到success的字樣表示基本鏡像已經建立完成 也能夠經過docker images來查看鏡像

發佈基本鏡像到私有的庫中

本案例使用的私有庫是 Nexus Repository Manager(OSS 3.0.2.02),同時支持maven、npm、nuget、docker、gem等，挺好的一個工具.因公司已經存在了就沒有使用docker官方推薦的私有庫的方案

登陸到私有庫

root@managert:~ # docker login https://mvn.source.org:9990

Username: 12860
Password:

用戶名和密碼是登陸OSS的帳戶 若是登陸過程當中出現錯誤信息

Error response from daemon: Get https://mvn.source.org:9990/v1/users/: http: server gave HTTP response to HTTPS client

表示當前登陸的私有庫不受信任，須要修改配置文件。配置內容以下：

**若是login操做時候提示以上錯誤，則須要在/etc/docker/daemon.json(不存在則新增)增長一行內容:

{ "insecure-registries":["mvn.source.org:9990"] }

爲剛剛建好的鏡像添加tag

root@managert:~ # docker tag 39a3b68429a7 mvn.source.org:9990/centos:lastest

上傳鏡像

root@managert:~ # docker push  mvn.source.org:9990/centos:lastest

The push refers to a repository [mvn.source.org:9990/centos]
14e19e279e3e: Pushed 
a7d98c277f49: Pushed 
tornado: digest: sha256:eee628902e1495a03d82988f8e0801c9b4dd91aca23e101e38e36c6eadd199bc size: 742

下載鏡像

root@managert:~ # docker pull  mvn.source.org:9990/centos:lastest

至此，完成了一個基礎鏡像的建立、私有庫上傳及下載的過程，後續過程將探索若是基於基礎鏡像建立其餘特定應用領域的鏡像，完成自動化部署。