我可以从dockerfile中的docker映像中复制目录吗？

Question

I am trying to build a simple java web application(not maven) from within my docker file by pulling code from my git server and creating a deployable war.In order to do so I have to copy the classes directory to my WEB-INF Folder .My classes directory is at /usr/app_name/build/classes (in the docker image) and I want to copy it to /usr/app_name/WebContent/WEB-INF/ (within the same image).

Here is my docker file:

FROM maven:3.5-jdk-8 AS buildserver
WORKDIR /usr/app_name
RUN git clone http://uname:pass@git_server_host:git_server_port/scm/tes/app_name.git /usr/app_name 

COPY /usr/app_name/build/classes /usr/app_name/WebContent/WEB-INF/
#***#Is there any way to perform above operation***

WORKDIR /usr/app_name/WebContent/WEB-INF/
RUN jar -cvf app_name.war *
FROM tomcat:latest
COPY --from=buildserver /usr/app_name/WebContent/WEB-INF/app_name.war .
EXPOSE 5060

Answer 1

The COPY command in docker only works for copying files from the docker host machine to the image being built. You can do what you need by just running a cp command in the image (or using rsync or some other tool if you have them installed in the container). An example of this would be:

RUN cp -r /usr/app_name/build/classes /usr/app_name/WebContent/WEB-INF/

to copy the contents to /usr/app_name/WebContent/WEB-INF/classes , or:

RUN cp -r /usr/app_name/build/classes/* /usr/app_name/WebContent/WEB-INF/

if you want to copy the content to /usr/app_name/WebContent/WEB-INF directly.