Question

我正在为应用程序构建Dockerfile。我想在容器开始运行时执行带参数的bash脚本，所以我把它作为一个入口点。但是，Docker找不到我的脚本所在的目录。这个脚本位于Intellij Idea项目文件夹中，路径实际上如下所示：/home/user/Documents/folder1/folder2/folder3/Projectname/runapp.sh

我尝试将此目录挂载为卷，但在运行构建映像时发生错误：

docker: Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "exec: \"runapp.sh\": executable file not found in $PATH": unknown.

这种行为可能是什么原因？我怎么能从Dockerfile到达这个bash脚本？

这是Dockerfile的样子：

FROM java:8

ENV SCALA_VERSION 2.11.8
ENV SBT_VERSION 1.1.1
ENV SPARK_VERSION 2.2.0
ENV SPARK_DIST spark-$SPARK_VERSION-bin-hadoop2.6
ENV SPARK_ARCH $SPARK_DIST.tgz
ENV NEO4J_CONFIG default
ENV BENCHMARK_NAME default

WORKDIR /opt

# Install Scala
RUN \
  cd /root && \
  curl -o scala-$SCALA_VERSION.tgz http://downloads.typesafe.com/scala/$SCALA_VERSION/scala-$SCALA_VERSION.tgz && \
  tar -xf scala-$SCALA_VERSION.tgz && \
  rm scala-$SCALA_VERSION.tgz && \
  echo >> /root/.bashrc && \
  echo 'export PATH=~/scala-$SCALA_VERSION/bin:$PATH' >> /root/.bashrc

# Install SBT
RUN \
  curl -L -o sbt-$SBT_VERSION.deb https://dl.bintray.com/sbt/debian/sbt-$SBT_VERSION.deb && \
  dpkg -i sbt-$SBT_VERSION.deb && \
  rm sbt-$SBT_VERSION.deb

# Install Spark
RUN \
    cd /opt && \
    curl -o $SPARK_ARCH http://d3kbcqa49mib13.cloudfront.net/$SPARK_ARCH && \
    tar xvfz $SPARK_ARCH && \
    rm $SPARK_ARCH && \
    echo 'export PATH=$SPARK_DIST/bin:$PATH' >> /root/.bashrc

EXPOSE 9851 9852 4040 7474 7687 7473

VOLUME /home/user/Documents/folder1/folder2/folder3/Projectname /workdir1

WORKDIR /workdir1

ENTRYPOINT ["runapp.sh"]

CMD ["$NEO4J_CONFIG", "$BENCHMARK_NAME"]

Answer 1

You misunderstood volumes in Docker I think. (see What is the purpose of VOLUME in Dockerfile)

I'm citing @VonC answer:

A volume is a persistent data stored in /var/lib/docker/volumes/...

You can either declare it in a Dockerfile, which means each time a container is stated from the image, the volume is created (empty), even if you don't have any -v option.

You can declare it on runtime docker run -v [host-dir:]container-dir. combining the two (VOLUME + docker run -v) means that you can mount the content of a host folder into your volume persisted by the container in /var/lib/docker/volumes/....

docker volume create creates a volume without having to define a Dockerfile and build an image and run a container. It is used to quickly allow other containers to mount said volume.

So you should use docker run -v /home/user/Documents/folder1/folder2/folder3/Projectname:/workdir1 when starting the container

And your Dockerfile volume declaration should be:

VOLUME /workdir1

That being said, you define both Entrypoint and CMD. What is the CMD being for ? You will never use your image without using runapp.sh ? I prefer using only CMD for development since you can still do docker run -it my_container bash for debugging purpose with this syntax.

This time I'm using @Daishi answer from What is the difference between CMD and ENTRYPOINT in a Dockerfile?

The ENTRYPOINT specifies a command that will always be executed when the container starts.

The CMD specifies arguments that will be fed to the ENTRYPOINT.

If you want to make an image dedicated to a specific command you will use ENTRYPOINT ["/path/dedicated_command"]

Otherwise, if you want to make an image for general purpose, you can leave ENTRYPOINT unspecified and use CMD ["/path/dedicated_command"] as you will be able to override the setting by supplying arguments to docker run

Moreover, runapp.sh isn't in your $PATH and you call it without absolute path, so it will not find the file even if the volume is mounted correctly. You could just use:

CMD /workdir1/runapp.sh "$NEO4J_CONFIG" "$BENCHMARK_NAME"

Now be careful, on your host you mention that the shell script is named script.sh and you call runapp.sh in your Dockerfile, I hope it's a typo. By the way your script needs to be executable.

$ PATH Dockerfile中找不到可执行文件

1 个答案: