Python/Docker : FileNotFoundError: [Errno 2] No such file or directory:

Question

I am using a Python code to open a text file and write some information and close it. When I run this code on Jupyter notebook it runs perfectly but when I run this as a part of Docker container it gives the following error.

Current directory is C:/app where I have stored Dockerfile, testfile.txt and Hello1.py. In addition I have gone to Virtual Machine and have added C: as shared folder.

Python File

  file = open("C:/Python/testfile.txt","w")
  file.write("Hello World")
  file.write("This is our new text file")
  file.close()

Docker File

 FROM python:latest
 WORKDIR /data
 COPY testfile.txt /data
 COPY Hello1.py /data
 CMD ["python","Hello1.py"]

Error Recieved

 $ docker run sid1980
 Traceback (most recent call last):
 File "Hello1.py", line 7, in <module>
 file = open("C:/Python/testfile.txt","w")
 FileNotFoundError: [Errno 2] No such file or directory: 'C:/Python/testfile.txt'

Solution 1

Your python program cannot access C:/ of the host machine. You need to change the file path to reference the testfile.txt that exists within the container.

file = open("/data/testfile.txt","w")

Also note that this will not modify the testfile.txt that exists on the host. It will write to the file that is inside the container.

Solution 2

I was having a very similar error and just fixed it, so I hope this answer helps.

So, what happens is when you do docker run IMAGE, and your code inside the image accesses a file, it is relative to the root of the image.

So if your actual fd looks like this:

Python
 testfile.txt

And the fd in your image looks like this:

directory
 randomfile.txt

Then, you are going to get an error, because there is no Python directory, much less a testfile.txt, inside the image.

So, what you can do, at least in Mac, is that you can use the --volume flag when doing docker run to specify where you want to local file to appear in the docker image. For example, you can do something like docker run --name IMAGENAME --volume /Python:/usr/directory/Python to have your Python folder be staged at /usr/directory/Python inside the image. Then, you can use the "staged" folder in your code by writing in your code something like

file = open("C:/usr/Python/testfile.txt","w")

(Not sure exactly what the root of the image is considered on Windows, so use pwd to confirm)

Of course, change the argument for where you want the folder/file to appear in the image to your needs. This link was pretty helpful when I was solving this problem: https://docs.docker.com/storage/volumes/#choose-the--v-or---mount-flag.

P.S. If you want to see what the file directory of your image looks like, you can do docker exec IMAGENAME bash after docker running it.

Comments

[Peter Wood]

You say the directory is named app but in the code it is named Python

[Sid1980]

I am talking about the present working directory from where I am building Docker image.

[Sid1980]

Hello New Contributor I changed my python code to reflect your suggestion and rebuilt the image with name sid1980. When I use the command $ docker run -v //c/Sid:/data sid1980 and it still gives the error python: can't open file 'EIA.py': [Errno 2] No such file or directory

[Eduardo Hernández]

Not sure you can do that mount with v //c/Sid:/data. What I would do is getting inside the folder I'm trying to mount with the powershell and enter pwd, copy the output as the first part of the mount. I would even do it all at once like -v $(pwd):/data.