如何处理使用同一Dockerfile的应用程序的多个变体？

Question

我们想知道如何参数化构建过程。我们有一个应用程序，如果在编译时有合适的库，它就可以有特性。此外，我们还可以选择将其他一些调试应用程序包含到同一映像中。

我们当前的策略是在Dockerfile中注释输入/输出行，并将其编译为另一个名称。

# Dockerfile in multiple variants / t-shirt sizing:
# - as is, with all the #something; comments: very basic compilation without features
# - removing #something; enable a variant/feature

# see build and test instructions below

###
# REQUIRED: INSTALL COMPILER, DOWNLOAD AND INSTALL BITS AND PIECES
###
# start from a fedora 28 image
FROM    fedora:28 AS compiler_build
RUN     echo "############################# COMPILER IMAGE #################################"

# install requirements
#RUN     dnf upgrade -y && dnf clean all
RUN     dnf install -y git gcc gcc-c++ make automake autoconf gettext-devel

#######
#  OPTIONAL: CAM SUPPORT 
#######
#cam;RUN     dnf install -y wget mercurial patch glibc-static
#cam;
#cam;# do not use pre-built dvb-apps and libdvbcsa from distro-mirror, but build from sources. This is required for cam support on fedora.
#cam;RUN     cd /usr/local/src && \
#cam;        hg clone http://linuxtv.org/hg/dvb-apps && \
#cam;        cd dvb-apps && \
#cam;        # patching for >=4.14 Kernel (https://aur.archlinux.org/packages/linuxtv-dvb-apps)
#cam;        wget -q -O - https://git.busybox.net/buildroot/plain/package/dvb-apps/0003-handle-static-shared-only-build.patch | patch -p1 && \
#cam;        wget -q -O - https://git.busybox.net/buildroot/plain/package/dvb-apps/0005-utils-fix-build-with-kernel-headers-4.14.patch | patch -p1 && \
#cam;        wget -q -O - https://gitweb.gentoo.org/repo/gentoo.git/plain/media-tv/linuxtv-dvb-apps/files/linuxtv-dvb-apps-1.1.1.20100223-perl526.patch | patch -p1 && \
#cam;        make && make install && \
#cam;        ldconfig   # b/c libdvben50221.so

#######
# OPTIONAL: SCAM SUPPORT 
#######
#scam;RUN     yum install -y openssl-devel dialog svn pcsc-lite pcsc-lite-devel libusb libusb-devel findutils file libtool
#scam;
#scam;RUN     cd /usr/local/src && \
#scam;        git clone https://code.videolan.org/videolan/libdvbcsa.git && \
#scam;        cd libdvbcsa && \
#scam;        autoreconf -i -f && \
#scam;        ./configure --prefix=/usr && make && make install && \
#scam;        ldconfig   # b/c libdvbcsa.so
#scam;        #dnf install -y https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm && \
#scam;        #dnf install -y libdvbcsa-devel
#scam;
#scam;RUN     cd /usr/local/src && \
#scam;        svn checkout http://www.streamboard.tv/svn/oscam/trunk oscam-svn && \
#scam;        cd oscam-svn && \
#scam;        make USE_PCSC=1 USE_LIBUSB=1
#scam;         
#scam;RUN     cd /usr/local/src && \
#scam;        git clone https://github.com/gfto/tsdecrypt.git && \
#scam;        cd tsdecrypt && \
#scam;        git submodule init && \
#scam;        git submodule update && \
#scam;        make && make install    

#######  
# REQUIRED: ACTUAL APPLICATION ITSELF
#######
# note: the ./configure will detect cam/scam support automagically if everything provided
RUN     cd /usr/local/src && \
        ldconfig && \
        git clone https://github.com/braice/MuMuDVB.git && \
        cd MuMuDVB && \
        autoreconf -i -f && \
        ./configure --enable-android && \
        make && make install

#######
# OPTIONAL: TOOLBOXING
####### 
#tool;RUN     cd /usr/local/src && \
#tool;        git clone git://git.videolan.org/bitstream.git && \
#tool;        cd bitstream && \
#tool;        make all && make install
#tool;
#tool;RUN     cd /usr/local/src && \
#tool;        dnf install -y libev-devel && \
#tool;        git clone https://code.videolan.org/videolan/dvblast.git && \
#tool;        cd dvblast && \
#tool;        make all && make install
#tool;         
#tool;RUN     cd /usr/local/src && \
#tool;        yum install -y wget bzip2 && \
#tool;        wget http://wirbel.htpc-forum.de/w_scan/w_scan-20170107.tar.bz2 && \
#tool;        tar -jxf w_scan-20170107.tar.bz2 && \
#tool;        cd w_scan-20170107/ && \
#tool;        ./configure && make && make install
#tool;          
#tool;RUN     cd /usr/local/src && \
#tool;        git clone https://github.com/stefantalpalaru/w_scan2.git && \
#tool;        cd w_scan2 && \
#tool;        autoreconf -i -f && \
#tool;        ./configure && make && make install
#tool;         
#tool;RUN     cd /usr/local/src && \
#tool;      yum install -y wget && \
#tool;        wget http://udpxy.com/download/udpxy/udpxy-src.tar.gz && \
#tool;        tar -zxf udpxy-src.tar.gz && \
#tool;        cd udpxy-*/ && \
#tool;        make && make install 
#tool;          
#tool;RUN     cd /usr/local/src && \
#tool;        yum install -y xz wget && \
#tool;        wget ftp://ftp.videolan.org/pub/videolan/miniSAPserver/0.3.8/minisapserver-0.3.8.tar.xz && \
#tool;        tar -Jxf minisapserver-0.3.8.tar.xz && \
#tool;        cd minisapserver-*/ && \
#tool;        ./configure && make && make install
#tool;
#tool;RUN     cd /usr/local/src && \
#tool;        yum install -y wget && \
#tool;        wget https://dl.bintray.com/tvheadend/fedora/bintray-tvheadend-fedora-4.2-stable.repo

###
# OPTIONAL: START OVER AND ONLY RE-INSTALL
###
FROM    fedora:28
RUN     echo "############################# RUNTIME IMAGE #################################"

# copy the whole /usr/local from the previous compiler-image (note the --from)
COPY    --from=compiler_build /usr/local /usr/local

# install runtime libraries
#scam;RUN     dnf install -y openssl-devel pcsc-lite libusb
#tool;RUN     dnf install -y v4l-utils libev
#tool;RUN     mv /usr/local/src/bintray-tvheadend-fedora-4.2-stable.repo /etc/yum.repos.d
#tool;RUN     dnf search tvheadend # experimental


# unfortunately, some make's need gcc anyway :(
RUN     dnf install -y make gcc gcc-c++ cpp glibc-devel glibc-headers kernel-headers

# re-install all the stuff from before
RUN     test -e /usr/local/src/dvb-apps && cd /usr/local/src/dvb-apps && make install && ldconfig || exit 0
RUN     test -e /usr/local/src/libdvbcsa && cd /usr/local/src/libdvbcsa && make install && ldconfig || exit 0
RUN     cd /usr/local/src/MuMuDVB && make install && mumudvb -v
RUN     test -e /usr/local/src/tsdecrypt && cd /usr/local/src/tsdecrypt && make install || exit 0
RUN     test -e /usr/local/src/bitstream && cd /usr/local/src/bitstream && make install || exit 0
RUN     test -e /usr/local/src/dvblast && cd /usr/local/src/dvblast && make install || exit 0
RUN     test -e /usr/local/src/w_scan-20170107 && cd /usr/local/src/w_scan-20170107 && make install || exit 0
RUN     test -e /usr/local/src/w_scan2 && cd /usr/local/src/w_scan2 && make install || exit 0
RUN     test -e /usr/local/src/udpxy-*/ && cd /usr/local/src/udpxy-*/ && make install || exit 0
RUN     test -e /usr/local/src/minisapserver-*/ && cd /usr/local/src/minisapserver-*/ && make install || exit 0

# remove gcc again
RUN     dnf remove -y make gcc gcc-c++ cpp glibc-devel glibc-headers kernel-headers

RUN     echo "############################# FINAL STEPS #################################"

# add a runtime user
RUN     useradd -c "simple user" -g users -G audio,video,cdrom,dialout,lp,tty,games user

# include this very file into the image
COPY    Dockerfile /

# use this user as default user
USER    user

# assume persistent storage
VOLUME  /tmp

# assume exposed ports
EXPOSE  8500:8500

# assume standard runtime executable
CMD     ["/bin/bash"]

###
# RECOMMENDED: HOW TO BUILD AND TEST
###

# build mumudvb plain:
#     cat Dockerfile.template > Dockerfile;                              time docker build -t my_mumudvb_simple .
# enable cam/scam support:
#     sed -r 's_^#(cam|scam);__g' Dockerfile.template > Dockerfile;      time docker build -t my_mumudvb_cam .
# enable tool but not scam support:
#     sed -r 's_^#(tool);__g' Dockerfile.template > Dockerfile;          time docker build -t my_mumudvb_tool .
# enable all support:
#     sed -r 's_^#(cam|scam|tool);__g' Dockerfile.template > Dockerfile; time docker build -t my_mumudvb_full .

# simpe compare and test
# $ docker run -it --rm my_mumudvb_simple /bin/bash
# $ docker run -it --rm my_mumudvb_full /usr/local/bin/w_scan
# $ docker run -it --rm my_mumudvb_cam /usr/local/bin/mumudvb
# $ docker run -it --rm my_mumudvb_tool /usr/local/bin/mumudvb

# run a scan. note the mapped device tree /dev/dvb
# $ docker run -it --rm --device /dev/dvb/ my_mumudvb_full w_scan -f s -s S13E0 -D1c

# run a mumudvb instance. Note the mapped device, filesystem and tcp-port
# $ docker run -it --rm --device /dev/dvb/ --volume ${PWD}/conf:/conf -p 8500:8500 my_mumudvb_cam mumudvb -d -c /conf/test.conf

你能推荐如何实现和管理它吗？重新使用编译中间图像可以节省一些空间和时间，使用标签可以简化变体的使用等。

你有什么建议？

Answer 1

排列是否以某种方式分层？如果是这样的话，您可以创建中间图像并继承它们。这将有一个好处，即构建的“祖先”部分将是预先构建的，并且不需要更多的构建时间(当然，除非它们发生变化)。

如果没有，你可以使用你最喜欢的脚本语言来构建你的Dockerfile。你如何做到这一点并不重要，重要的是你把它自动化了。我建议使用数组为每个命名的构建指定它应该包含的部分。因为这将运行得很快，所以您可以随时组合所有Dockerfile，并使其成为您在构建映像时自己所做的事情，这样您对Dockerfile的规范就不会与Dockerfile本身不同步。

事实上，如果你这样做了，你可能有必要不提交你的Dockerfile到版本控制，因为这是一个与你的脚本定义不同步的事情。

附录

关于这句话：

我们可以选择将其他一些调试应用程序包含到同一镜像中。

在这里，值得注意的是什么构成了测试图像。如果将可选的调试工具添加到映像中，则：

• 如果不打算将其部署到生产环境中，那么您最终可能需要针对未在生产环境中使用的应用程序版本进行测试。理想的做法是在整个开发工作流程中始终使用相同的图像。
• 如果要将其部署到生产环境中，则值得考虑是否可以增加攻击面。

Answer 2

看看在Dockerfile中使用ARG和ENV。ARG设置在构建映像时可用的值。ENV设置可用的变量，并在构建后与映像保持一致。

例如，假设您需要基于DEV或PRD版本的不同设置文件，您可以这样做：

ARG=settings_filename
ENV=settings_filename=${settings_filename}

然后调用docker来构建镜像，如下所示：

docker build --build-arg settings_filename="settings.dev"

Dockerfile文件中的ARG行将该值设置为"settings.dev"，但ARG值不会持久保存到映像中。无论ARG值是什么，ENV行实际上都作为环境变量保存在所生成的图像中。