Docker build Error: no such file or directory

Question

I am trying to do a basic docker learning and building an image.

My directory structure currently looks like below:

/Documents/docker_test/
├── docker_python
├── hello_world.py

The file docker_python is the docker file name. hello_world.py is a basic hello_world python script I am trying to run it by default when the container is created of the image.

The contents of that docker file look like below:

### Dockerfile 

# Created by Baktawar

# Pulling from base Python image 

FROM python:3.6.7-alpine3.6

# author of file
LABEL maintainer=”Baktawar”

# Set the working directory of the docker image 
WORKDIR /app
COPY . /app


# packages that we need
RUN pip install numpy && \
    pip install pandas && \
    pip install jupyter


EXPOSE 8888

ENTRYPOINT ["python"]

CMD ["hello_world.py"]

When I run it using

docker_test$ docker build -t docker_python . 

unable to prepare context: unable to evaluate symlinks in Dockerfile path: lstat /Documents/docker_test/Dockerfile: no such file or directory

Answer 1

To make the build work immediatly, your build command should be:

docker build -f docker_python -t docker_python . 

By default, the build command will look for a file named Dockerfile in the build context that you supply (in your case you supply . aka. the current working directory). If you want to override this default, use the -f switch and supply your filename. Note that the Dockerfile always needs to be in the build context.

The docker build syntax simplified:

docker build -f <dockerfile> -t <imagetag> <buildcontext>

If you rename the file docker_python in your project, to just Dockerfile, you can simply build with the command that you are already trying:

docker build -t docker_python . 

The docker build reference is a worthwhile read if you want to learn more.

Update

Since you are having trouble with the maintainer LABEL now, I will include a full Dockerfile for you here:

### Dockerfile 
# Created by Baktawar
# Pulling from base Python image 

FROM python:3.6.7-alpine3.6

# author of file
LABEL maintainer="Baktawar"

# Set the working directory of the docker image 
WORKDIR /app
COPY . /app


# packages that we need
RUN pip install numpy && \
    pip install pandas && \
    pip install jupyter

EXPOSE 8888

ENTRYPOINT ["python"]

CMD ["hello_world.py"]

I only replaced the double quotes in the line:

LABEL maintainer="Baktawar"

Update

Next issue seems to be with the numpy installation. And yes, this is indeed a known issue on alpine. I managed to solve the issue with the following Dockerfile:

### Dockerfile
# Created by Baktawar
# Pulling from base Python image

FROM python:3.6.7-alpine3.6

# author of file
LABEL maintainer="Baktawar"

# Set the working directory of the docker image
WORKDIR /app
COPY . /app

# Install native libraries, required for numpy
RUN apk --no-cache add musl-dev linux-headers g++

# Upgrade pip
RUN pip install --upgrade pip

# packages that we need
RUN pip install numpy && \
    pip install pandas && \
    pip install jupyter

EXPOSE 8888

ENTRYPOINT ["python"]

CMD ["hello_world.py"]

Apparently, numpy requires some native libraries to be able to install. I also upgraded pip for you, I got a warning about the version.

To your question, should you build like this:

docker build -f dockerfile -t docker_python .

If you Dockerfile is named dockerfile - the answer is "Yes". You can only ommit the -f switch, if your Dockerfile is named exactly Dockerfile. It is case sensitive.

Answer 2

That error is happening because, by default, docker build expects a file called Dockerfile. Since yours is called docker_python, you need to use the --file , -f option, and then pass the name of your file.

--file , -f     Name of the Dockerfile (Default is ‘PATH/Dockerfile’)

Check the Official Docker Documentation for more information.