Docker 构建自定义镜像和Dockerfile文件

1、基本结构

Dockerfile 文件一般包含基础镜像信息、维护者信息、镜像操作指令和容器启动时执行指令，’#’ 为 Dockerfile 中的注释。

2、文件写法

Docker以从上到下的顺序运行Dockerfile文件中指令。为了指定基本映像，第一条指令必须是FROM。一个声明以＃字符开头则被视为注释。可以在Docker文件中使用RUN，CMD，FROM，EXPOSE，ENV等指令。

常用的指令如下表：

3、Dockerfile文件示例

1）Java JDK镜像

FROM alpine:latestADD jdk-8u211-linux-x64.tar.gz /usr/local/RUN echo http://mirrors.ustc.edu.cn/alpine/v3.9/main > /etc/apk/repositories && \    echo http://mirrors.ustc.edu.cn/alpine/v3.9/community >> /etc/apk/repositories && \    apk update && apk upgradeRUN apk --no-cache add ca-certificates wget && \    wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://alpine-pkgs.sgerrand.com/sgerrand.rsa.pub && \    wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.29-r0/glibc-2.29-r0.apk && \    apk add glibc-2.29-r0.apkENV JAVA_HOME=/usr/local/jdk1.8.0_211ENV CLASSPATH=$JAVA_HOME/binENV PATH=.:$JAVA_HOME/bin:$PATHCMD ["java","-version"]

2）Python3 镜像

FROM alpine:3.14ENV PATH /usr/local/bin:$PATH# http://bugs.python.org/issue19846# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.ENV LANG C.UTF-8# runtime 依赖RUN set -eux; \apk add --no-cache \# 安装ca-certificates，使HTTPS工作一致ca-certificates \# and tzdata for PEP 615 (https://www.python.org/dev/peps/pep-0615/)tzdata \;# Python的其他运行时依赖项稍后安装ENV GPG_KEY E3FF2839C048B25C084DEBE9B26995E310250568ENV PYTHON_VERSION 3.9.8RUN set -ex \&& apk add --no-cache --virtual .fetch-deps \gnupg \tar \xz \\&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \&& export GNUPGHOME="$(mktemp -d)" \&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \&& gpg --batch --verify python.tar.xz.asc python.tar.xz \&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \&& rm -rf "$GNUPGHOME" python.tar.xz.asc \&& mkdir -p /usr/src/python \&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \&& rm python.tar.xz \\&& apk add --no-cache --virtual .build-deps  \bluez-dev \bzip2-dev \coreutils \dpkg-dev dpkg \expat-dev \findutils \gcc \gdbm-dev \libc-dev \libffi-dev \libnsl-dev \libtirpc-dev \linux-headers \make \ncurses-dev \openssl-dev \pax-utils \readline-dev \sqlite-dev \tcl-dev \tk \tk-dev \util-linux-dev \xz-dev \zlib-dev \# 在移除获取deps之前添加构建deps，以防有重叠&& apk del --no-network .fetch-deps \\&& cd /usr/src/python \&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \&& ./configure \--build="$gnuArch" \--enable-loadable-sqlite-extensions \--enable-optimizations \--enable-option-checking=fatal \--enable-shared \--with-system-expat \--with-system-ffi \--without-ensurepip \&& make -j "$(nproc)" \# 将线程堆栈大小设置为1MB，这样就不会在遇到sys.getrecursionlimit()之前出现段错误。# https://github.com/alpinelinux/aports/commit/2026e1259422d4e0cf92391ca2d3844356c649d0EXTRA_CFLAGS="-DTHREAD_STACK_SIZE=0x100000" \LDFLAGS="-Wl,--strip-all" \&& make install \&& rm -rf /usr/src/python \\&& find /usr/local -depth \\( \\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \\) -exec rm -rf '{}' + \\&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec scanelf --needed --nobanner --format '%n#p' '{}' ';' \| tr ',' '\n' \| sort -u \| awk 'system("[ -e /usr/local/lib/" $1 " ]") == 0 { next } { print "so:" $1 }' \| xargs -rt apk add --no-cache --virtual .python-rundeps \&& apk del --no-network .build-deps \\&& python3 --version# 制作一些预计会存在的有用符号链接RUN cd /usr/local/bin \&& ln -s idle3 idle \&& ln -s pydoc3 pydoc \&& ln -s python3 python \&& ln -s python3-config python-configENV PYTHON_PIP_VERSION 21.2.4# https://github.com/docker-library/python/issues/365ENV PYTHON_SETUPTOOLS_VERSION 57.5.0# https://github.com/pypa/get-pipENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/3cb8888cc2869620f57d5d2da64da38f516078c7/public/get-pip.pyENV PYTHON_GET_PIP_SHA256 c518250e91a70d7b20cceb15272209a4ded2a0c263ae5776f129e0d9b5674309RUN set -ex; \\wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum -c -; \\python get-pip.py \--disable-pip-version-check \--no-cache-dir \"pip==$PYTHON_PIP_VERSION" \"setuptools==$PYTHON_SETUPTOOLS_VERSION" \; \pip --version; \\find /usr/local -depth \\( \\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \-o \\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \\) -exec rm -rf '{}' +; \rm -f get-pip.pyCMD ["python3"]

3）nginx 镜像

## NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"##FROM debian:buster-slimLABEL maintainer="NGINX Docker Maintainers "ENV NGINX_VERSION   1.20.1ENV NJS_VERSION     0.5.3ENV PKG_RELEASE     1~busterRUN set -x \# 首先创建nginx用户/组，以在整个docker变体中保持一致    && addgroup --system --gid 101 nginx \    && adduser --system --disabled-login --ingroup nginx --no-create-home --home /nonexistent --gecos "nginx user" --shell /bin/false --uid 101 nginx \    && apt-get update \    && apt-get install --no-install-recommends --no-install-suggests -y gnupg1 ca-certificates \    && \    NGINX_GPGKEY=573BFD6B3D8FBC641079A6ABABF5BD827BD9BF62; \    found=''; \    for server in \        ha.pool.sks-keyservers.net \        hkp://keyserver.ubuntu.com:80 \        hkp://p80.pool.sks-keyservers.net:80 \        pgp.mit.edu \    ; do \        echo "Fetching GPG key $NGINX_GPGKEY from $server"; \        apt-key adv --keyserver "$server" --keyserver-options timeout=10 --recv-keys "$NGINX_GPGKEY" && found=yes && break; \    done; \    test -z "$found" && echo >&2 "error: failed to fetch GPG key $NGINX_GPGKEY" && exit 1; \    apt-get remove --purge --auto-remove -y gnupg1 && rm -rf /var/lib/apt/lists/* \    && dpkgArch="$(dpkg --print-architecture)" \    && nginxPackages=" \        nginx=${NGINX_VERSION}-${PKG_RELEASE} \        nginx-module-xslt=${NGINX_VERSION}-${PKG_RELEASE} \        nginx-module-geoip=${NGINX_VERSION}-${PKG_RELEASE} \        nginx-module-image-filter=${NGINX_VERSION}-${PKG_RELEASE} \        nginx-module-njs=${NGINX_VERSION}+${NJS_VERSION}-${PKG_RELEASE} \    " \    && case "$dpkgArch" in \        amd64|i386|arm64) \            echo "deb https://nginx.org/packages/debian/ buster nginx" >> /etc/apt/sources.list.d/nginx.list \            && apt-get update \            ;; \        *) \            echo "deb-src https://nginx.org/packages/debian/ buster nginx" >> /etc/apt/sources.list.d/nginx.list \            \# 用于存储源文件和.deb文件的新目录            && tempDir="$(mktemp -d)" \            && chmod 777 "$tempDir" \# (777 to ensure APT's "_apt" user can access it too)            \# 保存当前安装的包列表，以便稍后可以干净地删除构建依赖项            && savedAptMark="$(apt-mark showmanual)" \            \            && apt-get update \            && apt-get build-dep -y $nginxPackages \            && ( \                cd "$tempDir" \                && DEB_BUILD_OPTIONS="nocheck parallel=$(nproc)" \                    apt-get source --compile $nginxPackages \            ) \# 在这里不删除APT列表，因为它们会被重新下载并删除            \            && apt-mark showmanual | xargs apt-mark auto > /dev/null \            && { [ -z "$savedAptMark" ] || apt-mark manual $savedAptMark; } \            \# 创建一个临时的本地APT repo来安装            && ls -lAFh "$tempDir" \            && ( cd "$tempDir" && dpkg-scanpackages . > Packages ) \            && grep '^Package: ' "$tempDir/Packages" \            && echo "deb [ trusted=yes ] file://$tempDir ./" > /etc/apt/sources.list.d/temp.list \            && apt-get -o Acquire::GzipIndexes=false update \            ;; \    esac \    \    && apt-get install --no-install-recommends --no-install-suggests -y \                        $nginxPackages \                        gettext-base \                        curl \    && apt-get remove --purge --auto-remove -y && rm -rf /var/lib/apt/lists/* /etc/apt/sources.list.d/nginx.list \    \    && if [ -n "$tempDir" ]; then \        apt-get purge -y --auto-remove \        && rm -rf "$tempDir" /etc/apt/sources.list.d/temp.list; \    fi \# 转发请求日志和错误日志到docker日志采集器    && ln -sf /dev/stdout /var/log/nginx/access.log \    && ln -sf /dev/stderr /var/log/nginx/error.log \# 创建一个docker-entrypoint.d 目录    && mkdir /docker-entrypoint.dCOPY docker-entrypoint.sh /COPY 10-listen-on-ipv6-by-default.sh /docker-entrypoint.dCOPY 20-envsubst-on-templates.sh /docker-entrypoint.dCOPY 30-tune-worker-processes.sh /docker-entrypoint.dENTRYPOINT ["/docker-entrypoint.sh"]EXPOSE 80STOPSIGNAL SIGQUITCMD ["nginx", "-g", "daemon off;"]

4、构建生成Docker镜像

编写好构建的镜像的Dockerfile文件后，可以docker build 命令构建生成镜像，如下，

docker build  -t ImageName:TagName dir

-t ：是提及图像的标签

ImageName ：要为镜像命名的名称。

TagName ：要为镜像提供的标签。

Dir ：Docker 文件所在的目录。

例如，

docker build -t wonhero/centos7-jdk1.7 .