Docker多阶段ONBUILD不执行第一阶段onbuild命令

Question

我正在尝试为一个Java项目创建一个多阶段的ONBUILD镜像，请参见下面的示例。第一次迭代在检查构建结果时，似乎只在最后阶段看到了ONBUILD命令。

FROM maven:3.6.3-jdk-11-slim AS build
RUN mkdir /project
WORKDIR /project
ONBUILD COPY pom.xml /project
ONBUILD RUN mvn dependency:go-offline --batch-mode
ONBUILD COPY . /project
ONBUILD RUN mvn package

FROM adoptopenjdk/openjdk11:jre-11.0.6_10-alpine
RUN mkdir /app
WORKDIR /app
ONBUILD COPY --from=build /project/target/*.jar /app/application.jar

CMD ["java", "-jar", "application.jar"]

我决定将阶段划分为2个图像，然后将它们组合到应用程序图像中。

FROM maven:3.6.3-jdk-11-slim AS build
RUN mkdir /project
WORKDIR /project
ONBUILD COPY pom.xml /project
ONBUILD RUN mvn dependency:go-offline --batch-mode
ONBUILD COPY . /project
ONBUILD RUN mvn package

FROM adoptopenjdk/openjdk11:jre-11.0.6_10-alpine
RUN mkdir /app
WORKDIR /app
ONBUILD COPY --from=build /project/target/*.jar /app/application.jar

CMD ["java", "-jar", "application.jar"]

通过以下方式组合这两个图像后，检查两个图像会显示正确的ONBUILD命令：

FROM maven-jdk-11-onbuild:latest as build

FROM jre-11-onbuild:latest

结果，它只从第二个映像执行ONBUILD COPY命令。

[+] Building 0.2s (6/6) FINISHED
 => [internal] load build definition from Dockerfile                                                                                                                   0.0s
 => => transferring dockerfile: 120B                                                                                                                                           0.0s
 => [internal] load .dockerignore                                                                                                                                              0.0s
 => => transferring context: 34B                                                                                                                                               0.0s
 => [internal] load metadata for docker.io/library/jre-11:onbuild                                                                                                                                                                                                           0.0s
 => CACHED [build 1/1] FROM docker.io/library/maven-jdk-11:onbuild                                                                                                     0.0s
 => CACHED [stage-1 1/1] FROM docker.io/library/jre-11:onbuild                                                                                                                                                                                                              0.0s
 => ERROR [stage-1 2/1] COPY --from=build /app/target/*.jar /app/application.jar                                                                                               0.1s
------
 > [stage-1 2/1] COPY --from=build /app/target/*.jar /app/application.jar:
------
lstat /var/lib/docker/overlay2/daced0019dbfe2605e586b5607160adb3358c22054ae2762a0338b3681eddd33/merged/app/target: no such file or directory

看起来第一个阶段由于某种原因被缓存了。可以将多阶段构建与ONBUILD逻辑结合起来吗？

Answer 1

这在我之前的几次更新中是有效的(Docker for MacOS)。