二、容器化技术-docker镜像、容器

系列文章目录

文章目录

• 目录

  系列文章目录

• 文章目录

  前言

  一、物理机、VM、docker

  二、image探究

  1.仓库源

  2.image和layer的关系

  总结

  ---

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前言

去了新公司线上应用部署环境由传统服务器直接部署变为使用docker，并且感觉以前部署应用方式不够优雅，面对微服务体系资源利用率不够高，所以学习docker。

    所有百度云盘提取码都为1111

---

提示：以下是本篇文章正文内容，下面案例可供参考

一、物理机、VM、docker

        最主要的是虚拟机和容器化技术区别，docker这种容器化技术优势在于硬件、网络资源更加高效使用，资源分配与回收更加符合现代应用部署的需求。虚拟机创建是划分大量资源，出现闲置只能整体销毁。docker可以使用较少资源创建一个微型的操作系统，资源回收更加方便。

    根据上图可以看出docker分为三部分，docker CLI、API、server。client调用api定义的指令，server针对不同平台实现api功能类似于jvm。network解决容器《==》容器、容器《==》宿主机、容器集群《==》容器集群、物理机《==》物理机的网络管理，data volumes解决数据持久化。

1. image ≈ java Class 类是唯一一个，通过dockerfile定义image。
2. container ≈ java 对象 通过类创建一个个对象，容器通过镜像创建。

二、image探究

1.仓库源

https://github.com/docker-library

        例如查找tomcat镜像，下图可以看出tomcat各个版本。根据不同Dockerfile.debian创建不容版本容器，在下边可以看出文件内容。

FROM openjdk:8-jdk-buster

ENV CATALINA_HOME /usr/local/tomcat
ENV PATH $CATALINA_HOME/bin:$PATH
RUN mkdir -p "$CATALINA_HOME"
WORKDIR $CATALINA_HOME

# let "Tomcat Native" live somewhere isolated
ENV TOMCAT_NATIVE_LIBDIR $CATALINA_HOME/native-jni-lib
ENV LD_LIBRARY_PATH ${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}$TOMCAT_NATIVE_LIBDIR

# see https://www.apache.org/dist/tomcat/tomcat-$TOMCAT_MAJOR/KEYS
# see also "update.sh" (https://github.com/docker-library/tomcat/blob/master/update.sh)
ENV GPG_KEYS 05AB33110949707C93A279E3D3EFE6B686867BA6 07E48665A34DCAFAE522E5E6266191C37C037D42 47309207D818FFD8DCD3F83F1931D684307A10A5 541FBE7D8F78B25E055DDEE13C370389288584E7 5C3C5F3E314C866292F359A8F3AD5C94A67F707E 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 765908099ACF92702C7D949BFA0C35EA8AA299F1 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 8B46CA49EF4837B8C7F292DAA54AD08EA7A0233C 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23

ENV TOMCAT_MAJOR 8
ENV TOMCAT_VERSION 8.5.69
ENV TOMCAT_SHA512 3ce092c7b89a12904681f23c9c8a2517c13305b4beb783f7b1e85e947aaba4d2bfe8f954f9cefbe009f678557eeb552995f214d9e98c3f1be395822eb2582a1c

RUN set -eux; \
	\
	savedAptMark="$(apt-mark showmanual)"; \
	apt-get update; \
	apt-get install -y --no-install-recommends \
		gnupg dirmngr \
		wget ca-certificates \
	; \
	\
	ddist() { \
		local f="$1"; shift; \
		local distFile="$1"; shift; \
		local mvnFile="${1:-}"; \
		local success=; \
		local distUrl=; \
		for distUrl in \
# https://issues.apache.org/jira/browse/INFRA-8753?focusedCommentId=14735394#comment-14735394
			"https://www.apache.org/dyn/closer.cgi?action=download&filename=$distFile" \
# if the version is outdated (or we're grabbing the .asc file), we might have to pull from the dist/archive :/
			"https://www-us.apache.org/dist/$distFile" \
			"https://www.apache.org/dist/$distFile" \
			"https://archive.apache.org/dist/$distFile" \
# if all else fails, let's try Maven (https://www.mail-archive.com/[email protected]/msg134940.html; https://mvnrepository.com/artifact/org.apache.tomcat/tomcat; https://repo1.maven.org/maven2/org/apache/tomcat/tomcat/)
			${mvnFile:+"https://repo1.maven.org/maven2/org/apache/tomcat/tomcat/$mvnFile"} \
		; do \
			if wget -O "$f" "$distUrl" --progress=dot:giga && [ -s "$f" ]; then \
				success=1; \
				break; \
			fi; \
		done; \
		[ -n "$success" ]; \
	}; \
	\
	ddist 'tomcat.tar.gz' "tomcat/tomcat-$TOMCAT_MAJOR/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz" "$TOMCAT_VERSION/tomcat-$TOMCAT_VERSION.tar.gz"; \
	echo "$TOMCAT_SHA512 *tomcat.tar.gz" | sha512sum --strict --check -; \
	ddist 'tomcat.tar.gz.asc' "tomcat/tomcat-$TOMCAT_MAJOR/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz.asc" "$TOMCAT_VERSION/tomcat-$TOMCAT_VERSION.tar.gz.asc"; \
	export GNUPGHOME="$(mktemp -d)"; \
	for key in $GPG_KEYS; do \
		gpg --batch --keyserver keyserver.ubuntu.com --recv-keys "$key"; \
	done; \
	gpg --batch --verify tomcat.tar.gz.asc tomcat.tar.gz; \
	tar -xf tomcat.tar.gz --strip-components=1; \
	rm bin/*.bat; \
	rm tomcat.tar.gz*; \
	command -v gpgconf && gpgconf --kill all || :; \
	rm -rf "$GNUPGHOME"; \
	\
# https://tomcat.apache.org/tomcat-9.0-doc/security-howto.html#Default_web_applications
	mv webapps webapps.dist; \
	mkdir webapps; \
# we don't delete them completely because they're frankly a pain to get back for users who do want them, and they're generally tiny (~7MB)
	\
	nativeBuildDir="$(mktemp -d)"; \
	tar -xf bin/tomcat-native.tar.gz -C "$nativeBuildDir" --strip-components=1; \
	apt-get install -y --no-install-recommends \
		dpkg-dev \
		gcc \
		libapr1-dev \
		libssl-dev \
		make \
	; \
	( \
		export CATALINA_HOME="$PWD"; \
		cd "$nativeBuildDir/native"; \
		gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)"; \
		aprConfig="$(command -v apr-1-config)"; \
		./configure \
			--build="$gnuArch" \
			--libdir="$TOMCAT_NATIVE_LIBDIR" \
			--prefix="$CATALINA_HOME" \
			--with-apr="$aprConfig" \
			--with-java-home="$JAVA_HOME" \
			--with-ssl=yes; \
		make -j "$(nproc)"; \
		make install; \
	); \
	rm -rf "$nativeBuildDir"; \
	rm bin/tomcat-native.tar.gz; \
	\
# reset apt-mark's "manual" list so that "purge --auto-remove" will remove all build dependencies
	apt-mark auto '.*' > /dev/null; \
	[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark > /dev/null; \
	find "$TOMCAT_NATIVE_LIBDIR" -type f -executable -exec ldd '{}' ';' \
		| awk '/=>/ { print $(NF-1) }' \
		| xargs -rt readlink -e \
		| sort -u \
		| xargs -rt dpkg-query --search \
		| cut -d: -f1 \
		| sort -u \
		| xargs -r apt-mark manual \
	; \
	apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
	rm -rf /var/lib/apt/lists/*; \
	\
# sh removes env vars it doesn't support (ones with periods)
# https://github.com/docker-library/tomcat/issues/77
	find ./bin/ -name '*.sh' -exec sed -ri 's|^#!/bin/sh$|#!/usr/bin/env bash|' '{}' +; \
	\
# fix permissions (especially for running as non-root)
# https://github.com/docker-library/tomcat/issues/35
	chmod -R +rX .; \
	chmod 777 logs temp work; \
	\
# smoke test
	catalina.sh version

# verify Tomcat Native is working properly
RUN set -eux; \
	nativeLines="$(catalina.sh configtest 2>&1)"; \
	nativeLines="$(echo "$nativeLines" | grep 'Apache Tomcat Native')"; \
	nativeLines="$(echo "$nativeLines" | sort -u)"; \
	if ! echo "$nativeLines" | grep -E 'INFO: Loaded( APR based)? Apache Tomcat Native library' >&2; then \
		echo >&2 "$nativeLines"; \
		exit 1; \
	fi

EXPOSE 8080
CMD ["catalina.sh", "run"]

1. 拉起远程镜像，根据镜像运行容器

2. 可以将上述内容放入Dockerfile文件中build成为镜像，然后运行

 访问这个宿主机映射为7777的tomcat

 在win 10上访问虚拟机，虚拟机与docker端口进行映射。虚拟机7777==》docker id=3ba71265bc43的8080

       只需要将webapps.dis中root项目在一个容器内移动一次，别的项目就能直接访问是因为启动时候将容器持久化位置挂在虚拟机的同一个位置上。红色的命令代表挂载

docker run -d -p 7777:8080 -v /root/tomcat/:/usr/local/tomcat/webapps/ ecd199dd86fe

2.image和layer的关系

       因为在docker中，image是由多个layer组合而成的，换句话就是layer是一个共享的层，可能有多个image会指向某个layer。例如下边mysql的image Centos、Ubuntu Image就是layer相当于java中类的引入概念。

    咱们自定义一个Dockerfile然后build成为image,根据语法能够看出layer与image的关系。应用jar包

FROM openjdk:8
MAINTAINER 法外狂徒张三 
LABEL name="dockerfile-demo" version="1.0" author="法外狂徒张三"
COPY dockerfile-demo-0.0.1-SNAPSHOT.jar dockerfile-image.jar
CMD ["java","-jar","dockerfile-image.jar"]

docker build -t test-docker-image .
docker run --name user01 -p 9999:8080 test-docker-image

总结

解释了docker的image、container意义，说明了image如何生成。