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Docker containers crashed: /bin/sh: 1: [uvicorn,: not found

I am new to Docker and trying to Dockerize my FastAPI application.
First I created a Dockerfile:
FROM python:3.9.9
WORKDIR /usr/src/app
COPY requirements.txt ./
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]
Then ran the following command:
docker build -t fastapi .
The command ran successfully.
After that I created the following docker-compose.yml:
version: "3"
services:
api:
build: .
ports:
- 8000:8000
env_file:
./.env
Then ran the following command:
docker-compose up -d
Ran successfully:
Network fastapi_default Created 0.7s
- Container fastapi_api_1 Started
Then to check if its running properly I ran the following command:
docker ps -a
And it showed that Container exited few seconds after it was created.
Then I ran this command:
docker logs fastapi_api_1
And it says:
/bin/sh: 1: [uvicorn,: not found
Not sure what is the reason. Tried some solutions that I found online but nothing worked out. I do have uvicorn in my requirements.txt file.
Help will be appriciated. Please let me know if additional information is required.

Note: You don't need to do docker build -t fastapi . manually. Docker-compose will do it for you (because you set build: .) But! You must run up command with --build parameter (docker-compose up --build) to force rebuild image even if it exists.
And about your problem:
Here is a very good article (and one more) about RUN, ENTRYPOINT and CMD
Here is three forms for CMD:
CMD ["executable","param1","param2"] (exec form, preferred)
CMD ["param1","param2"] (sets additional default parameters for ENTRYPOINT in exec form)
CMD command param1 param2 (shell form)
According error, looks like Docker interpreting CMD as a shell form or additional parameters for default ENTRYPOINT
Actually still not sure why it happens, but changing CMD to
CMD uvicorn app.main:app --host 0.0.0.0 --port 8000
or
ENTRYPOINT ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]
should solve your problem
Also it will be better to use full path to uvicorn executable (/usr/bin/uvicorn or where it installed by default?). It is just my opinion but, that is may be a reason why CMD is interpreted as parameters instead of command.
PS In addition here is note from docker docs:
Note
The exec form is parsed as a JSON array, which means that you must use double-quotes (“) around words not single-quotes (‘).
So exec form syntax must meet the conditions of JSON syntax.

So, basically there was something wrong with the docker. I had created mulitple images. I removed all of them and ran the same commands again and it worked. I don't know the exact reason but its working now.
What I think was happening is that instead of deleting the old images and creating new one. I was just doing
docker-compose down
and then
docker-compose up -t
I think that command was not taking the changes into consideration.
then i ran:
docker-compose up --build
and I think that created a new image and it worked.
Then I noticed that there were atleast 10 images created. I deleted all of them and ran the same commands:
docker build .
docker-compose up -t
and it worked fine again.
So basically instead of using creating new image it was using the old one which was not created correctly:
docker-compose up --build
In short you should use docker-compose up --build whenever you make changes in your dockerfile or docker-compose.yml instead of docker-compose up -t
It might be confusing but I am also very new to Docker.
Thanks for the help everyone!

I've had the same issue with a Dockerfile in my docker-compose environment containing
COPY ./requirements.txt /app/requirements.txt
RUN pip install -r /app/requirements.txt
RUN pip install uvicorn==0.20.0
CMD ["uvicorn", "--host", "0.0.0.0", "--port", "6000", "app:app"]
So I don't need an extra command:line in my docker-compose.yml
It turned out that if you install uvicorn in your requirements.txt, as I like to do for testing purposes
then it gets installed locally, and
RUN pip install uvicorn==0.20.0 is skipped, which means,
there is no /usr/bin/uvicorn 'executable' available, just somewhere in site-packages and CMD will fail.
So, if you use uvicorn in your requirements.txt, and in Dockerfile as well, you can maybe
force the reinstallation
RUN pip install --ignore-installed uvicorn==0.20.0
in the Dockerfile,
or set the PATH to find it somewhere in the guts of python,
or - what I find is a better solution to keep the image size small -
is to remove uvicorn from requirements.txt...

Running pytest command outside of docker container failes because container stopped

I use docker selenium grid and pytest to execute tests. What i now do is:
Spin up selenium grid via a makerfile
Spin up the docker container (with a volume pointing to my local pc for the tests). The container also runs the pytest command.
This all works good, except that i would rather split the second action and be able to run the test on an already running container. Preferred setup:
Spin up selenium grid + docker container with pyton+pytest
A command to run the tests (with the container as interpretor)
When i tried to do this, i faced the issue that the python+pytest container stops running when the commands are all done. There is no long living process.
Dockerfile
FROM python:3.9.0-alpine
RUN apk add tk
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
RUN ls ..
CMD pytest --junitxml ../r/latest.xml
My docker-compose file looks like:
docker-compose.yml
version: "3.0"
services:
pytest:
container_name: pytest
build:
context: .
dockerfile: Dockerfile
volumes:
- ./t:/t
- ./r:/r
working_dir: /t/
networks:
default:
name: my_local_network #same as selenium grid
It does not 'feel' good to have this pytest command in the container settings itself.

Container shutting down
That's because the CMD pytest --junitxml ../r/latest.xml line will execute once and when complete it will exit the container.
To run a cmd on an existing container
You can run commands on an existing docker container using this command:
docker exec <container_name> python -m pytest
Where <container_name> would be pytest in your case, since that is what the container is called in your docker-compose.yml file.
See here for more info: https://docs.docker.com/engine/reference/commandline/exec/
Using Make
If you want to extend this to a makefile command:
docker:
docker-compose up -d
ci-tests: docker
docker exec <container_name> python -m pytest
To both spin up AND run tests you can use:
make ci-tests
You could run selenium-grid in docker too if you wanted to make this solution completely portable: https://www.conductor.com/nightlight/running-selenium-grid-using-docker-compose/

docker-compose running container with command but command only works manually in container

I have a docker-compose file that includes a service configured like:
py_publisher:
build:
context: ./client
dockerfile: Dockerfile
deploy:
mode: replicated
replicas: 3
# entrypoint: "python3 mqtt_client.py"
The image is built from this Dockerfile:
# syntax=docker/dockerfile:1
FROM python:3.8-slim-buster
WORKDIR /mqtt_client
COPY . .
RUN pip3 install -r requirements.txt
CMD ["python3", "mqtt_client.py"]
The home dir (/mqtt_client) of the container contains:
Dockerfile mqtt_client.py requirements.txt
The relevant docker-compose results:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
61b8f5e1e0bb e1d0fc27a640 "python3 mqtt_client…" 7 seconds ago Up 2 seconds mqtt-demo_py_publisher_1
9992b9c9031d e1d0fc27a640 "python3 mqtt_client…" 7 seconds ago Up 3 seconds mqtt-demo_py_publisher_2
a197f0f3126b e1d0fc27a640 "python3 mqtt_client…" 7 seconds ago Up 2 seconds mqtt-demo_py_publisher_3
The issue is that the Python command is not actually "working". Simply nothing happens. However, when I exec into the containers and run that exact command, it works fine.
What's the difference in the way I'm running via docker-compose and running it manually exec'ed into the container?

the proper way to do it, is by using entrypoint and the command. e.g.
ENTRYPOINT ["python3"]
CMD ["mqtt_client.py"]
since you are using python image already, you can drop the ENTRYPOINT instruction and only keep CMD.

docker entrypoint behaviour with django

I'm trying to make my first django container with uwsgi. It works as follows:
FROM python:3.5
RUN apt-get update && \
apt-get install -y && \
pip3 install uwsgi
COPY ./projects.thux.it/requirements.txt /opt/app/requirements.txt
RUN pip3 install -r /opt/app/requirements.txt
COPY ./projects.thux.it /opt/app
COPY ./uwsgi.ini /opt/app
COPY ./entrypoint /usr/local/bin/entrypoint
ENV PYTHONPATH=/opt/app:/opt/app/apps
WORKDIR /opt/app
ENTRYPOINT ["entrypoint"]
EXPOSE 8000
#CMD ["--ini", "/opt/app/uwsgi.ini"]
entrypoint here is a script that detects whether to call uwsgi (in case there are no args) or python manage in all other cases.
I'd like to use this container both as an executable (dj migrate, dj shell, ... - dj here is python manage.py the handler for django interaction) and as a long-term container (uwsgi --ini uwsgi.ini). I use docker-compose as follows:
web:
image: thux-projects:3.5
build: .
ports:
- "8001:8000"
volumes:
- ./projects.thux.it/web/settings:/opt/app/web/settings
- ./manage.py:/opt/app/manage.py
- ./uwsgi.ini:/opt/app/uwsgi.ini
- ./logs:/var/log/django
And I manage in fact to serve the project correctly but to interact with django to "check" I need to issue:
docker-compose exec web entrypoint check
while reading the docs I would have imagined I just needed the arguments (without entrypoint)
Command line arguments to docker run will be appended after
all elements in an exec form ENTRYPOINT, and will override all
elements specified using CMD. This allows arguments to be passed to
the entry point, i.e., docker run -d will pass the -d argument
to the entry point.
The working situation with "repeated" entrypoint:
$ docker-compose exec web entrypoint check
System check identified no issues (0 silenced).
The failing one if I avoid 'entrypoint':
$ docker-compose exec web check
OCI runtime exec failed: exec failed: container_linux.go:346: starting container process caused "exec: \"check\": executable file not found in $PATH": unknown

docker exec never uses a container's entrypoint; it just directly runs the command you give it.
When you docker run a container, the entrypoint and command you give to start it are combined to produce a single command line, and that command becomes the main container process. On the other hand, when you docker exec a command in a running container, it's interpreted literally; there aren't two parts of the command line to assemble, and the container's entrypoint isn't considered at all.
For the use case you describe, you don't need an entrypoint script to process the command in an unusual way. You can create a symlink to the manage.py script to give a shorter alias to run it, but make the default command be the uwsgi runner.
RUN chmod +x manage.py
RUN ln -s /opt/app/manage.py /usr/local/bin/dj
CMD ["uwsgi", "--ini", "/opt/app/uwsgi.ini"]
# Runs uwsgi:
docker run -p 8000:8000 myimage
# Manually trigger database migrations:
docker run --rm myimage dj migrate

how to run server using docker container?

Django server is running well in localhost. however, When I try to run server on the docker container, it doesn't find the manage.py file when using docker-compose file and even I run the container manually and run the server, it doesn't appear in browser. how can I solve this problem?
So I wrote all the code testing on my local server and using the dockerfile, I built the image of my project.
and I tried to run server on the docker container, suddenly this doesn't run.
what's worse, if I use docker-compose to run the server, it doesn't find the manage.py file though I already checked with 'docker run -it $image_name sh'
here is the code of my project
I am new to docker and new to programming.
hope you can give me a help. thanks!
file structure
current directory
└─example
└─db.sqlite3
└─docker-compose.yml
└─Dockerfile
└─manage.py
└─Pipfile
└─Pipfile.lock
Docker file
# Base image - Python version
FROM python:3.6-alpine
# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# Set work directory
WORKDIR /code
# Copy Pipfile
COPY Pipfile /code
COPY Pipfile.lock /code
# Install dependencies
RUN pip install pipenv
RUN pipenv install --system
# Copy files
COPY . /code/
docker-compose.yml
# docker-compose.yml
version: '3.3'
services:
web:
build: .
command: python /code/manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- 8000:8000
expected result : running server in web browser like in chrome
actual result :
when using docker-compose :
ERROR like this in the prompt : web_1 | python: can't open file '/code/manage.py': [Errno 2] No such file or directory
when running the container manually with 'docker run -it $image_name sh' and 'python manage.py runserver' on the shell :
server is running but, doesn't connect to web browser. (doesn't show up in browser like chrome'

Yo have done same thing in many ways. You have copy source files using a COPY command and then you have mounted a host volume in your docker-compose.yml file. In first place you don't need a volume because volume mounts are to persisting data generated by and used by Docker containers.
Following simplified Dockerfile and docker-compose file would fix the problem.
# Base image - Python version
FROM python:3.6-alpine
# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# Copy files
COPY . /code/
# Set work directory
WORKDIR /code
# Install dependencies
RUN pip install pipenv
RUN pipenv install --system
docker-compose.yml -:
# docker-compose.yml
version: '3.3'
services:
web:
build: .
command: python ./manage.py runserver 0.0.0.0:8000
ports:
- 8000:8000