No such file or directory error while running Docker image

Question

I am learning Docker concept and trying to make a Docker image of my project. I have installed Docker Desktop for Windows and build the image successfully by using below command:

docker build -t ${IMAGE_NAME} .

But when I run following command docker run ${IMAGE_NAME}:${TAG} I am getting following file not found error:

D:\Projects\AI360\deep_auto_backbar_api>docker run dsbyprateekg:prateek_gupta python3: can't open file '/Prepare_Dataset/server_engine/server.py': [Errno 2] No such file or directory

My project structure is looks like:

And my Dockerfile.txt has following instructions:

FROM python: 3.6-stretch
MAINTAINER PrateekG

# install build utilities
RUN apt-get update && \
    apt-get install -y gcc make apt-transport-https ca-certificates build-essential

# check our python environment
RUN python3 version RUN pip3 --version

# Installing python dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy all the files from the project's root to the working directory 
COPY Prepare_Dataset/ .

# Running Python Application
CMD ["python3", "/Prepare_Dataset/server_engine/server.py"]

I suspect I am missing something related to file path. Please see my Dockerfile and my project structure and help me to find out what I am doing wrong here.

Answer 1

In my case I had to change the line separators from cr/lf (Windows) to lf (Unix/Linux/macOS). To do this in IntelliJ, you have to select your root folder in the Project window and the go to File -> File Properties -> Line Separators -> LF - Unix and macOS (\n)

Also see this answer

Answer 2

When you use COPY Prepare_Dataset/ . this will copy the content of the directory, not the directory itself so CMD path become invalid /Prepare_Dataset/server_engine/server.py.

You need to use

COPY Prepare_Dataset/ ./Prepare_Dataset/

so when you copy you can verify

Step 5/7 : COPY Prepare_Dataset/ ./Prepare_Dataset/
 ---> Using cache
 ---> 2c5c15c23f65
Step 6/7 : RUN ls | grep "Prepare_Dataset"
 ---> Running in 54147bd4740c
Prepare_Dataset

Better to keep convention to avoid such error in future.

# SEt workdirectory
WORKDIR /app
# Now it will copy to /app/
COPY Prepare_Dataset/ ./Prepare_Dataset
CMD ["Prepare_Dataset/server_engine/server.py"]

You can verify you problem using below steps.

COPY Prepare_Dataset/ .
#You will see the content but not the directory
RUN ls /

You will not able to see the directory but you can grep the any file in it.

Step 5/7 : COPY Prepare_Dataset/ .
 ---> Using cache
 ---> e4eec046c860
Step 6/7 : RUN ls | grep "Prepare_Dataset"
 ---> Running in 23e4b2aab3d1
The command '/bin/sh -c ls | grep "Prepare_Dataset"' returned a non-zero code: 1