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uwsgi.ini failed: No such file or directory when running Docker container

I have the following Dockerfile for my Dash app:
# syntax=docker/dockerfile:1
FROM python:3.8 AS build
RUN pip install --upgrade pip
COPY requirements.txt /srv/build/requirements.txt
RUN pip install --requirement /srv/build/requirements.txt
COPY . /srv/app
WORKDIR /srv
CMD ["uwsgi", "--ini", "uwsgi.ini"]
Which is being built as follows:
docker build -t dashboard .
And ran as follows:
docker run dashboard
The issue is that when I run it, I am encountering the following error:
realpath() of uwsgi.ini failed: No such file or directory [core/utils.c line 3662]
I have been attempting to unpack this more but still struggling. I tried switching around the directory structure of my project and adding uwsgi to the requirements.txt file which I saw recommended in other places. Unfortunately, that didn't fix the issue.
Any suggestions as to what I am doing wrong here?

Why are there differences in container contents depending on whether I `docker run ...`or `docker-compose run ...`?

I'm experiencing differences with the contents of a container depending on whether I open a bash shell via docker run -i -t <container> bash or docker-compose run <container> bash and I don't know/understand how this is possible.
To aid in the explanation, please see this screenshot from my terminal. In both instances, I am running the image called blaze which has been built from the Dockerfile in my code. One of the steps during the build is to create a virutalenv called venv, however when I open a bash shell via docker-compose this virtualenv doesn't seem to exist unlike when I run docker run ....
I am relatively new to setting up my own builds with Docker, but surely if they are both referencing the same image, the output of ls within a bash shell should be the same? I would greatly appreciate any help or guidance to resources that would explain what exactly is going wrong here...
As an additional point, running docker images shows that both commands must be using the same image...
Thanks in advance!
This is my Dockerfile:
FROM blaze-base-image:latest
# add an URL that PIP automatically searches (e.g., Azure Artifact Store URL)
ARG INDEX_URL
ENV PIP_EXTRA_INDEX_URL=$INDEX_URL
# Copy source code to docker image
RUN mkdir /opt/app
COPY . /opt/app
RUN ls /opt/app
# Install Blaze pip dependencies
WORKDIR /opt/app
RUN python3.7 -m venv /opt/app/venv
RUN /opt/app/venv/bin/python -m pip install --upgrade pip
RUN /opt/app/venv/bin/python -m pip install keyring artifacts-keyring
RUN touch /opt/app/venv/pip.conf
RUN echo $'[global]\nextra-index-url=https://www.index.com' > /opt/app/venv/pip.conf
RUN /opt/app/venv/bin/python -m pip install -r /opt/app/requirements.txt
RUN /opt/app/venv/bin/python -m spacy download en_core_web_sm
# Comment
CMD ["echo", "Container build complete"]
And this is my docker-compose.yml:
version: '3'
services:
blaze:
build: .
image: blaze
volumes:
- .:/opt/app

There are two intersecting things going on here:
When you have a Compose volumes: or docker run -v option mounting host content over a container directory, the host content completely replaces what's in the image. If you don't have a ./venv directory on the host, then there won't be a /opt/app/venv directory in the container. That's why, when you docker-compose run blaze ..., the virtual environment is missing.
If you docker run a container, the only options that are considered are those in that specific docker run command. docker run doesn't know about the docker-compose.yml file and won't take options from there. That means there isn't this volume mount in the docker run case, which is why the virtual environment reappears.
Typically in Docker you don't need a virtual environment at all: the Docker image is isolated from other images and Python installations, and so it's safe and normal to install your application into the "system" Python. You also typically want your image to be self-contained and not depend on content from the host, so you wouldn't generally need the bind mount you show.
That would simplify your Dockerfile to:
FROM blaze-base-image:latest
# Any ARG will automatically appear as an environment variable to
# RUN directives; this won't be needed at run time
ARG PIP_EXTRA_INDEX_URL
# Creates the directory if it doesn't exist
WORKDIR /opt/app
# Install the Python-level dependencies
RUN pip install --upgrade pip
COPY requirements.txt .
RUN pip install -r requirements.txt
# The requirements.txt file should list every required package
# Install the rest of the application
COPY . .
# Set the main container command to run the application
CMD ["./app.py"]
The docker-compose.yml file can be similarly simplified to
version: '3.8' # '3' means '3.0'
services:
blaze:
build: .
# Compose picks its own image name
# Do not need volumes:, the image is self-contained
and then it will work consistently with either docker run or docker-compose run (or docker-compose up).

How to run a python program using Singularity from a docker container?

I have created a docker container for my pure python program and have set python main.py to be executed when the container is run. Running the container works as expected on my local machine. However, I want to run the container on my institution's high-performance cluster. The cluster machines use Singularity, which I am using to pull my docker image hosted on Dockerhub (the repo is darshank11/ga_paci_final). However, when I try to run the Singularity container, I get the following error: python3: can't open file 'main.py': [Errno 2] No such file or directory.
I've tried to change the base image in the Dockerfile, for example from FROM python:latest to FROM ubuntu:latest. I've made sure the docker container worked on my local machine, and then got one of my co-workers to pull the container from Dockerhub and run it too. Everything works fine until I get to Singularity.
Here is my docker file:
FROM ubuntu:16.04
RUN apt-get update -y && \
apt-get install -y python3-pip python3-dev
RUN mkdir src
WORKDIR /src
COPY . /src
RUN pip3 install --upgrade pip
RUN pip3 install -r requirements.txt
CMD ["python3", "-u", "main.py"]

You're getting that error because the execution context is not what you're expecting. The run path in singularity is the current directory on the host OS (e.g., ~/ga_paci_final), which has been mounted into the singularity image.
As mentioned in the comments, one solution is to give the full path to the python file in the docker CMD statement. Another option is to modify the %runscript block of singularity definition file to something like:
%runscript
cd /src
python3 -u main.py
That way you ensure the run environment is identical between Docker and Singularity.

Building Docker image for a python flask web app. Image does not appear or requirements.txt not found

I am trying to create a build of a webapp I have created using Docker, but I have had no success. I've tried to follow two different tutorials but neither worked for me
Following Tutorial 1:
The build seemed to complete without any problems but I could not find the image file anywhere, and 'sudo docker ps -a' returned nothing.
Following through thtutorial 2:
I am now getting another error, that the requirements file is not found. I looked up solutions to that here, but it seems I am doing the correct thing by adding it to the build with the 'ADD requirements.txt /webapp' command. I checked that I spelled requirements right, haha. Now I do see it in 'sudo docker ps -a', but I dont see any image file and presumably it would not work if I did, since it could not find the requirements.
I'm quite confused as to what is wrong and how I should properly build a docker. How to I get it to find the requirements file, and then upon completing the "Build" command, actually have an image. Where is this image stored?
Below is the setup I have after following the second tutorial.
Dockerfile
FROM ubuntu:latest
#Update OS
RUN sed -i 's/# \(.*multiverse$\)/\1/g' /etc/apt/sources.list
RUN apt-get update
RUN apt-get -y upgrade
# Install Python
RUN apt-get install -y python-dev python-pip
# Add requirements.txt
ADD requirements.txt /webapp
# Install uwsgi Python web server
RUN pip install uwsgi
# Install app requirements
RUN pip install -r requirements.txt
# Create app directory
ADD . /webapp
# Set the default directory for our environment
ENV HOME /webapp
WORKDIR /webapp
# Expose port 8000 for uwsgi
EXPOSE 8000
ENTRYPOINT ["uwsgi", "--http", "0.0.0.0:8000", "--module", "app:app", "--processes", "1", "--threads", "8"]
CMD ["app.py"]
Requirements
Flask==0.12.1
itsdangerous==0.24
Jinja2==2.8
MarkupSafe==0.23
Werkzeug==0.11.5
SQLite3==3.18.0
Directory Structure (if it matters)
app.py
image_data.db
README.txt
requirements.txt
Dockerfile
templates
- index.html
static/
- image.js
- main.css
img/
- camera.png
images/
- empty
Current output of ' sudo docker ps -a'
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
663d4e096938 8f5126108354 "/bin/sh -c 'pip i..." 17 minutes ago Exited (1) 17 minutes ago admiring_agnesi

The requirements.txt should be in the same directory as your dockerfile exists. I see from the dockerfile that the requirements.txt is added to webapp but the
RUN pip install -r requirements.txt
is trying to find it in the current directory; You probably need to copy rquirement.txt to the current directory like
ADD requirements.txt .
Lets see if that works. I did not test it.
You can see the images by
docker images
and then run it like
docker run -t image_name

Docker. No such file or directory

I have some files which I want to move them to a docker container.
But at the end docker can't find a file..
The folder with the files on local machine are at /home/katalonne/flask4
File Structure if it matters:
The Dockerfile:
#
# First Flask App Dockerfile
#
#
# Pull base image.
FROM centos:7.0.1406
# Build commands
RUN yum install -y python-setuptools mysql-connector mysql-devel gcc python-devel
RUN easy_install pip
RUN mkdir /opt/flask4
WORKDIR /opt/flask4
ADD requirements.txt /opt/flask4
RUN pip install -r requirements.txt
ADD . /opt/flask4
# Define deafult command.
CMD ["python","hello.py"]
# Expose ports.
EXPOSE 5000
So I built the image with this command :
docker build -t flask4 .
I ran the container with volume by :
docker run -d -p 5000:5000 -v /home/Katalonne/flask4:/opt/flask4 --name web flask4
And when I want to run the file on the container :
docker logs -f web
I get this error that it can not find my hello.py file :
python: can't open file 'hello.py': [Errno 2] No such file or directory
What is my fault?
P.S. : I'm a Docker and Linux partially-noob.

The files and directories that are located in the same location as your Dockerfile are indeed available (temporarily) to your docker build. But, after the docker build, unless you have used ADD or COPY to move those files permanently to the docker container, they will not be available to your docker container after the build is done. This file context is for the build, but you want to move them to the container.
You can add the following command:
...
ADD . /opt/flask4
ADD . .
# Define deafult command.
CMD ["python","hello.py"]
The line ADD . . should copy over all the things in your temporary build context to the container. The location that these files will go to is where your WORKDIR is pointing to (/opt/flask4).
If you only wanted to add hello.py to your container, then use
ADD hello.py hello.py
So, when you run CMD ["python","hello.py"], the pwd that you will be in is /opt/flask4, and hello.py should be in there, and running the command python hello.py in that directory should work.
HTH.