# Dockerfile VOLUME

**URL:** <https://forums.docker.com/t/dockerfile-volume/91257>\
**Category:** Feature Requests\
**Tags:** docker, build\
**Created:** [March 26, 2020, 5:54pm UTC](https://forums.docker.com/t/dockerfile-volume/91257 "2020-03-26T17:54:00Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![jrepas](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@jrepas](https://forums.docker.com/u/jrepas)\
**Post date:** [March 26, 2020, 5:54pm UTC](https://forums.docker.com/t/dockerfile-volume/91257/1 "2020-03-26T17:54:00Z")

</div>

I am trying to better understand what VOLUME directive works.  
Here is an Docker example that works:  
FROM openjdk:7

WORKDIR /usr/src/apps  
COPY ./src /usr/src/apps  
RUN javac Hello.java  
CMD [“java”, “Hello”]

Here is an equivalent Dockerfile that does NOT work: Why?  
FROM openjdk:7

WORKDIR /usr/src/apps  
COPY ./src /usr/src/apps  
VOLUME /usr/src/apps  
RUN javac Hello.java  
CMD [“java”, “Hello”]

When I build and run the image in a container I get this:  
Sending build context to Docker daemon 23.55kB  
Step 1/6 : FROM openjdk:7  
—\> d735a2057e60  
Step 2/6 : WORKDIR /usr/src/apps  
—\> Using cache  
—\> e2edf0b3b5c8  
Step 3/6 : COPY ./src /usr/src/apps  
—\> Using cache  
—\> 639b1ebc7a1a  
Step 4/6 : VOLUME /usr/src/apps  
—\> Running in c60f4fe287db  
Removing intermediate container c60f4fe287db  
—\> fd900d528141  
Step 5/6 : RUN javac Hello.java  
—\> Running in cdfb259fb70f  
Removing intermediate container cdfb259fb70f  
—\> 66750ad94f0f  
Step 6/6 : CMD [“java”, “Hello”]  
—\> Running in d67329238ce4  
Removing intermediate container d67329238ce4  
—\> eaed5343512f  
Successfully built eaed5343512f  
Successfully tagged demo:latest

sudo docker run --name demo\_1 -it demo  
Error: Could not find or load main class Hello

But if I change the Dockerfile to:  
FROM openjdk:7

WORKDIR /usr/src/apps  
COPY ./src /usr/src/apps  
RUN javac Hello.java  
VOLUME /usr/src/apps  
CMD [“java”, “Hello”]

Here is the result! Why?  
1st run: WORKS  
sudo docker run --name demo\_1 -it demo  
Hello, World  
This is my first java Application

2nd run: FAILS  
sudo docker run --name demo\_2 -it -v $PWD/src:/usr/src/apps demo  
Error: Could not find or load main class Hello