为 Java 应用生成并运行容器映像

4 分钟

在本单元中，你将生成并运行容器映像。如前面所学，映像的运行中实例是一个容器。

生成容器映像

成功构造 Dockerfile 后，可以指示 Docker 为你生成容器映像。

注释

确保 Docker 运行时配置为生成 Linux 容器。此配置很重要，因为我们正在使用的 Dockerfile 引用的是针对 Linux 体系结构的容器映像（JDK/JRE）。

用于生成容器映像的命令是 docker build。使用 -t 参数指定容器标签， . 是 Docker 查找 Dockerfile 的位置。运行下面的命令：

docker build -t flightbookingsystemsample .

以下输出是典型的：

docker build -t flightbookingsystemsample .
[+] Building 45.2s (18/18) FINISHED     docker:desktop-linux
 => [internal] load build definition from Dockerfile    0.0s
 => => transferring dockerfile: 2.07kB                  0.0s
 => [internal] load metadata for mcr.microsoft.com/openjdk/jdk:17-ubuntu    0.7s
 => [internal] load metadata for mcr.microsoft.com/openjdk/jdk:17-mariner   0.8s
 => [internal] load .dockerignore                       0.0s
 => => transferring context: 2B                         0.0s
 => [internal] load build context                       0.4s
 => => transferring context: 9.89MB                     0.4s
 => [stage-2 1/4] FROM mcr.microsoft.com/openjdk/jdk:17-mariner@sha256:79****************************************f1ee692d5b8c36f0824510    15.9s
 => => resolve mcr.microsoft.com/openjdk/jdk:17-mariner@sha256:796b833b91****************************************5b8c36f0824510             0.0s

...

 => => extracting sha256:8f818432a4****************************************1791ae8c3b79ca                 2.4s
 => => extracting sha256:1820580505****************************************087e3a0df74b60                 7.1s
 => [build 1/7] FROM mcr.microsoft.com/openjdk/jdk:17-ubuntu@sha256:7982bc2eb79838d70bcc025371c514b7f7fde75f9981906c65eff04e9170627e       15.5s
 => => resolve mcr.microsoft.com/openjdk/jdk:17-ubuntu@sha256:7982bc2eb79838d70bcc025371c514b7f7fde75f9981906c65eff04e9170627e              0.0s

...

 => => extracting sha256:6414378b64****************************************b23a54cb3684ac                 2.4s
 => => extracting sha256:8debc97485****************************************80f38d9f1cb399                 6.5s
 => [build 2/7] WORKDIR /build                          0.4s
 => [tomcat 2/2] RUN apt-get update ;     apt-get install -y curl ;     curl -O https://downloads.apache.org/tomcat/tomcat-10/v10.1.33/bin/apache-tomcat-10.1.33.tar.gz ;     tar xzf apache-tomcat-10.1.33.tar.  23.4s
 => [build 3/7] RUN apt-get update && apt-get install -y maven && mvn --version                          14.5s
 => [build 4/7] COPY pom.xml .                          0.0s
 => [build 5/7] COPY src ./src                          0.0s
 => [build 6/7] COPY web ./web                          0.1s
 => [build 7/7] RUN mvn clean package                  13.4s
 => [stage-2 2/4] COPY --chown=app:app --from=tomcat /usr/local/tomcat /usr/local/tomcat                  0.2s
 => [stage-2 3/4] COPY --chown=app:app tomcat-users.xml /usr/local/tomcat/conf                            0.0s
 => [stage-2 4/4] COPY --chown=app:app --from=build /build/target/*.war /usr/local/tomcat/webapps/AirlinesReservationSample.war             0.1s
 => exporting to image                                  0.2s
 => => exporting layers                                 0.1s
 => => writing image sha256:43d4ab3ab0****************************************c4807bce5af7b4              0.0s
 => => naming to docker.io/library/flightbookingsystemsample

多阶段生成可以高效处理过程。具体而言，没有依赖项的进程并行执行。例如，在这种情况下，在阶段 0 中下载 Tomcat 以及第 1 阶段中 Maven 的安装和编译是独立的进程。因此，执行 docker build时，将同时执行 Tomcat 进程和 Maven 进程。但是，最终阶段从阶段 0 和阶段 1 复制项目，因此在完成以前的进程之前无法执行该项目。因此，最后阶段会等待前面的进程完成，并在有可能完成时继续。

此外，如果编辑程序的源代码的一部分并再次运行 docker build ，则预计该过程的完成速度比第一次要快。容器旨在将层结构与缓存配合使用，并且缓存中重复使用未更改的层。例如，如果 Java、Tomcat 或 Maven 版本没有更改，则重复使用以前下载的映像。在对源代码进行修改时，只需要更改流程的后半部分，该部分涉及替换源代码和重新生成项目以替换生成工件。请注意如何编写 Docker 命令，以便尽可能多地重用缓存来高效生成。

Docker 还可以显示驻留的可用映像，这有助于查看可供运行的内容。运行下面的命令：

docker images

以下输出是典型的：

docker images
REPOSITORY                  TAG      IMAGE ID     CREATED        SIZE
flightbookingsystemsample   latest   43d4ab3ab045 30 minutes ago 475MB

运行容器映像

成功生成容器映像后，可以运行它。

使用 docker run 命令运行容器映像。该 -p ####:#### 参数将 localhost HTTP 流量（冒号前的第一个端口）转发到运行时的容器，即冒号之后的第二个端口。 Dockerfile 指定 Tomcat 应用服务器正在侦听端口 8080 上的 HTTP 流量。因此，这就是你需要公开的容器端口。最后，需要映像标记 flightbookingsystemsample 来告知 Docker 要运行哪个映像。运行下面的命令：

docker run -p 8080:8080 flightbookingsystemsample

以下输出是典型的：

docker run -p 8080:8080 flightbookingsystemsample
15-Nov-2024 12:11:12.229 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version name:   Apache Tomcat/10.1.33
15-Nov-2024 12:11:12.236 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:          Nov 7 2024 22:28:55 UTC
15-Nov-2024 12:11:12.236 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version number: 10.1.33.0
15-Nov-2024 12:11:12.237 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:               Linux
15-Nov-2024 12:11:12.237 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:            6.10.11-linuxkit
15-Nov-2024 12:11:12.237 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:          amd64
15-Nov-2024 12:11:12.238 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Java Home:             /usr/lib/jvm/msopenjdk-17
15-Nov-2024 12:11:12.238 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:           17.0.13+11-LTS
15-Nov-2024 12:11:12.238 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:            Microsoft
15-Nov-2024 12:11:12.238 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:         /usr/local/tomcat
15-Nov-2024 12:11:12.239 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:         /usr/local/tomcat
15-Nov-2024 12:11:12.262 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.config.file=/usr/local/tomcat/conf/logging.properties
15-Nov-2024 12:11:12.262 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
15-Nov-2024 12:11:12.263 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=2048
15-Nov-2024 12:11:12.264 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.protocol.handler.pkgs=org.apache.catalina.webresources
15-Nov-2024 12:11:12.264 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dorg.apache.catalina.security.SecurityListener.UMASK=0027
15-Nov-2024 12:11:12.265 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.base/java.lang=ALL-UNNAMED
15-Nov-2024 12:11:12.266 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.base/java.io=ALL-UNNAMED
15-Nov-2024 12:11:12.267 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.base/java.util=ALL-UNNAMED
15-Nov-2024 12:11:12.267 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.base/java.util.concurrent=ALL-UNNAMED
15-Nov-2024 12:11:12.268 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: --add-opens=java.rmi/sun.rmi.transport=ALL-UNNAMED
15-Nov-2024 12:11:12.268 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.base=/usr/local/tomcat
15-Nov-2024 12:11:12.268 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=/usr/local/tomcat
15-Nov-2024 12:11:12.269 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.io.tmpdir=/usr/local/tomcat/temp
15-Nov-2024 12:11:12.271 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The Apache Tomcat Native library which allows using OpenSSL was not found on the java.library.path: [/usr/java/packages/lib:/usr/lib64:/lib64:/lib:/usr/lib]
15-Nov-2024 12:11:12.699 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-nio-8080"]
15-Nov-2024 12:11:12.760 INFO [main] org.apache.catalina.startup.Catalina.load Server initialization in [845] milliseconds
15-Nov-2024 12:11:12.855 INFO [main] org.apache.catalina.core.StandardService.startInternal Starting service [Catalina]
15-Nov-2024 12:11:12.855 INFO [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet engine: [Apache Tomcat/10.1.33]
15-Nov-2024 12:11:12.891 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/usr/local/tomcat/webapps/AirlinesReservationSample.war]
15-Nov-2024 12:11:15.150 INFO [main] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
15-Nov-2024 12:11:17.112 INFO [main] com.sun.xml.ws.server.MonitorBase.createRoot Metro monitoring rootname successfully set to: com.sun.metro:pp=/,type=WSEndpoint,name=/AirlinesReservationSample-PriceAndSeats-PriceAndSeatsPort
15-Nov-2024 12:11:17.400 INFO [main] com.sun.xml.ws.transport.http.servlet.WSServletDelegate.<init> WSSERVLET14: XML-WS servlet initializing
WARNING:Error in the metadata of the table SEATS: table's row count in the metadata is 5 but 6 records have been found and loaded by UCanAccess. All will work fine, but it's better to repair your database.
15-Nov-2024 12:11:18.281 INFO [main] com.sun.xml.ws.transport.http.servlet.WSServletContextListener.contextInitialized WSSERVLET12: XML-WS context listener initializing
15-Nov-2024 12:11:18.282 INFO [main] com.sun.xml.ws.transport.http.servlet.WSServletContextListener.contextInitialized WSSERVLET12: XML-WS context listener initializing
15-Nov-2024 12:11:18.320 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [/usr/local/tomcat/webapps/AirlinesReservationSample.war] has finished in [5,428] ms
15-Nov-2024 12:11:18.322 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [/usr/local/tomcat/webapps/ROOT]
15-Nov-2024 12:11:18.363 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [/usr/local/tomcat/webapps/ROOT] has finished in [40] ms
15-Nov-2024 12:11:18.363 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [/usr/local/tomcat/webapps/docs]
15-Nov-2024 12:11:18.404 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [/usr/local/tomcat/webapps/docs] has finished in [41] ms
15-Nov-2024 12:11:18.406 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [/usr/local/tomcat/webapps/examples]
15-Nov-2024 12:11:18.716 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [/usr/local/tomcat/webapps/examples] has finished in [310] ms
15-Nov-2024 12:11:18.717 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [/usr/local/tomcat/webapps/manager]
15-Nov-2024 12:11:18.753 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [/usr/local/tomcat/webapps/manager] has finished in [37] ms
15-Nov-2024 12:11:18.754 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [/usr/local/tomcat/webapps/host-manager]
15-Nov-2024 12:11:18.795 INFO [main] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [/usr/local/tomcat/webapps/host-manager] has finished in [40] ms
15-Nov-2024 12:11:18.802 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-nio-8080"]
15-Nov-2024 12:11:18.840 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in [6079] milliseconds

打开浏览器窗口，并访问航班预订系统的航空公司预订首页http://localhost:8080/AirlinesReservationSample/。您的浏览器应与以下截图类似：

显示正在运行的应用的屏幕截图。

可以选择使用 来自tomcat-users.xml 的任何用户登录，例如 someuser@azure.com: password。

若要停止容器，请在 CLI 中按 CTRL+C 。

为 Java 应用生成并运行容器映像

生成容器映像

运行容器映像

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