当与主机数据目录映射时，Docker容器数据变为空白。

Question

我创建了如下所示的Dockerfile。只是把一个应用程序加到tomcat网络应用程序中。

FROM tomcat:9-alpine  
ADD ./Spring3HibernateApp.war /usr/local/tomcat/webapps/  
VOLUME /usr/local/tomcat/webapps  
EXPOSE 8080  
CMD ["catalina.sh","run"] 

创建一个新的映像并将其命名为test-app:0.1

docker build –t test-app:0.1 .

像下面这样旋转新的容器，在这里我使用主机数据目录来挂载一个容器数据目录，这样我就可以修改或者列出容器的webapp内容。

docker run -d --name=tomcat-01 -p 80:8080 --net=bridge -v /vol2/docker/sampleapp/tomcat-webapps:/usr/local/tomcat/webapps test-app:0.1

我的问题:当我看到/vol2/docker/sampleapp/tomcat时，我发现它是空白的。然而，我认为它应该从位置/usr/local/tomcat/webapp中列出容器的内容。它实际上也在清理容器数据，而不是将其持久化并加载到主机数据目录中。

，我有遗漏什么吗？

如果我只是从上面的命令中删除-v，它可以很好地工作，并且我能够看到默认停靠器卷位置中的内容，但是当我添加-v时却不能得到相同的结果。

我理解错了吗?我指的是通过链接https://docs.docker.com/engine/tutorials/dockervolumes/将主机目录挂载为数据卷。

当我使用mysql映像并从中提取新容器时，相同的命令工作正常。

docker run -d --name=mysql-01 -p 3306:3306 -e MYSQL_ROOT_PASSWORD=password -e MYSQL_DATABASE=employeedb --net=bridge -v /vol2/docker/sampleapp/mysql-data:/var/lib/mysql mysql

这一次，我能够看到/vol2/docker/sampleapp/mysql-data中的容器数据。

Answer 1

挂载卷时，要覆盖容器内的现有目录。如果要从容器外部部署.war或.jar文件，则需要执行以下操作：

FROM tomcat:9-alpine
VOLUME /usr/local/tomcat/webapps
EXPOSE 8080
CMD ["catalina.sh","run"]

构建它：docker build –t test-app:0.1 .

然后像这样运行容器：docker run -d --name=tomcat-01 -p 80:8080 -v /vol2/docker/sampleapp/tomcat-webapps:/usr/local/tomcat/webapps test-app:0.1将Spring3HibernateApp.war放置在/vol2/docker/sampleapp/tomcat-webapps目录中。一旦你这样做，你可以去docker logs -f tomcat-01和观看tomcat部署的应用程序，就像在我的sample.war下面。

Using CATALINA_BASE:   /usr/local/tomcat
Using CATALINA_HOME:   /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JRE_HOME:        /usr/lib/jvm/java-1.8-openjdk/jre
Using CLASSPATH:       /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar
25-Feb-2017 21:58:23.710 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:        Apache Tomcat/9.0.0.M17
25-Feb-2017 21:58:23.717 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:          Jan 10 2017 20:59:20 UTC
25-Feb-2017 21:58:23.717 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server number:         9.0.0.0
25-Feb-2017 21:58:23.717 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:               Linux
25-Feb-2017 21:58:23.717 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:            3.13.0-93-generic
25-Feb-2017 21:58:23.717 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:          amd64
25-Feb-2017 21:58:23.717 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Java Home:             /usr/lib/jvm/java-1.8-openjdk/jre
25-Feb-2017 21:58:23.718 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:           1.8.0_111-internal-alpine-r0-b14
25-Feb-2017 21:58:23.718 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:            Oracle Corporation
25-Feb-2017 21:58:23.718 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:         /usr/local/tomcat
25-Feb-2017 21:58:23.718 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:         /usr/local/tomcat
25-Feb-2017 21:58:23.719 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.config.file=/usr/local/tomcat/conf/logging.properties
25-Feb-2017 21:58:23.719 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
25-Feb-2017 21:58:23.719 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=2048
25-Feb-2017 21:58:23.720 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.protocol.handler.pkgs=org.apache.catalina.webresources
25-Feb-2017 21:58:23.720 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.base=/usr/local/tomcat
25-Feb-2017 21:58:23.721 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=/usr/local/tomcat
25-Feb-2017 21:58:23.721 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.io.tmpdir=/usr/local/tomcat/temp
25-Feb-2017 21:58:23.721 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent Loaded APR based Apache Tomcat Native library 1.2.10 using APR version 1.5.2.
25-Feb-2017 21:58:23.721 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].
25-Feb-2017 21:58:23.722 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent APR/OpenSSL configuration: useAprConnector [false], useOpenSSL [true]
25-Feb-2017 21:58:23.725 INFO [main] org.apache.catalina.core.AprLifecycleListener.initializeSSL OpenSSL successfully initialized (OpenSSL 1.0.2j  26 Sep 2016)
25-Feb-2017 21:58:23.838 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-nio-8080"]
25-Feb-2017 21:58:23.861 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read
25-Feb-2017 21:58:23.868 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["ajp-nio-8009"]
25-Feb-2017 21:58:23.870 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read
25-Feb-2017 21:58:23.874 INFO [main] org.apache.catalina.startup.Catalina.load Initialization processed in 653 ms
25-Feb-2017 21:58:23.908 INFO [main] org.apache.catalina.core.StandardService.startInternal Starting service Catalina
25-Feb-2017 21:58:23.908 INFO [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet Engine: Apache Tomcat/9.0.0.M17
25-Feb-2017 21:58:23.951 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive /usr/local/tomcat/webapps/sample.war
25-Feb-2017 22:00:25.223 INFO [localhost-startStop-1] org.apache.catalina.util.SessionIdGeneratorBase.createSecureRandom Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [120,610] milliseconds.
25-Feb-2017 22:00:25.253 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive /usr/local/tomcat/webapps/sample.war has finished in 121,302 ms
25-Feb-2017 22:00:25.258 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler [http-nio-8080]
25-Feb-2017 22:00:25.270 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler [ajp-nio-8009]
25-Feb-2017 22:00:25.278 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 121403 ms

最后，MySQL卷挂载的工作方式和它一样，因为在构建VOLUME /var/lib/mysql之前，基本映像已经公开了卷，如果您想要在catalina应用程序中发生相同的事情，您必须复制他们的Dockerfile并向其中添加一个VOLUME /usr/local/tomcat/webapps/，如下所示。

FROM openjdk:8-jre-alpine

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

RUN apk add --no-cache gnupg

# 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 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23
RUN set -ex; \
    for key in $GPG_KEYS; do \
        gpg --keyserver ha.pool.sks-keyservers.net --recv-keys "$key"; \
    done

ENV TOMCAT_MAJOR 9
ENV TOMCAT_VERSION 9.0.0.M17

# https://issues.apache.org/jira/browse/INFRA-8753?focusedCommentId=14735394#comment-14735394
ENV TOMCAT_TGZ_URL https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-$TOMCAT_MAJOR/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz
# not all the mirrors actually carry the .asc files :'(
ENV TOMCAT_ASC_URL https://www.apache.org/dist/tomcat/tomcat-$TOMCAT_MAJOR/v$TOMCAT_VERSION/bin/apache-tomcat-$TOMCAT_VERSION.tar.gz.asc

RUN set -x \
    \
    && apk add --no-cache --virtual .fetch-deps \
        ca-certificates \
        tar \
        openssl \
    && wget -O tomcat.tar.gz "$TOMCAT_TGZ_URL" \
    && wget -O tomcat.tar.gz.asc "$TOMCAT_ASC_URL" \
    && gpg --batch --verify tomcat.tar.gz.asc tomcat.tar.gz \
    && tar -xvf tomcat.tar.gz --strip-components=1 \
    && rm bin/*.bat \
    && rm tomcat.tar.gz* \
    \
    && nativeBuildDir="$(mktemp -d)" \
    && tar -xvf bin/tomcat-native.tar.gz -C "$nativeBuildDir" --strip-components=1 \
    && apk add --no-cache --virtual .native-build-deps \
        apr-dev \
        gcc \
        libc-dev \
        make \
        "openjdk${JAVA_VERSION%%[-~bu]*}"="$JAVA_ALPINE_VERSION" \
        openssl-dev \
    && ( \
        export CATALINA_HOME="$PWD" \
        && cd "$nativeBuildDir/native" \
        && ./configure \
            --libdir="$TOMCAT_NATIVE_LIBDIR" \
            --prefix="$CATALINA_HOME" \
            --with-apr="$(which apr-1-config)" \
            --with-java-home="$(docker-java-home)" \
            --with-ssl=yes \
        && make -j$(getconf _NPROCESSORS_ONLN) \
        && make install \
    ) \
    && runDeps="$( \
        scanelf --needed --nobanner --recursive "$TOMCAT_NATIVE_LIBDIR" \
            | awk '{ gsub(/,/, "\nso:", $2); print "so:" $2 }' \
            | sort -u \
            | xargs -r apk info --installed \
            | sort -u \
    )" \
    && apk add --virtual .tomcat-native-rundeps $runDeps \
    && apk del .fetch-deps .native-build-deps \
    && rm -rf "$nativeBuildDir" \
    && rm bin/tomcat-native.tar.gz

# verify Tomcat Native is working properly
RUN set -e \
    && nativeLines="$(catalina.sh configtest 2>&1)" \
    && nativeLines="$(echo "$nativeLines" | grep 'Apache Tomcat Native')" \
    && nativeLines="$(echo "$nativeLines" | sort -u)" \
    && if ! echo "$nativeLines" | grep 'INFO: Loaded APR based Apache Tomcat Native library' >&2; then \
        echo >&2 "$nativeLines"; \
        exit 1; \
    fi
ADD ./Spring3HibernateApp.war /
VOLUME ${CATALINA_HOME}
EXPOSE 8080
CMD ["catalina.sh", "run"]

Answer 2

恐怕您的VOLUME /usr/local/tomcat/webapps清除了这个目录。

你得换个方法。

Answer 3

当您将主机目录挂载到容器中时，该路径上容器内的任何内容都不再可用。它仍然存在于底层图像或卷中，但它将被您的卷挂载所取代。

这就是主机卷挂载的工作方式:主机上目录中的任何内容都放在容器中，并且优先于以前在该路径中的任何内容(如果有的话)。