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FastAPI Docker error: exec "uvicorn": executable file not found in $PATH

FastAPI Docker error: exec "uvicorn": executable file not found in $PATH

David Y.

The ProblemJump To Solution

I’m attempting to Dockerize my FastAPI application, but it crashes with the following error right after I start up the containers with docker-compose:

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Cannot start service core: failed to create shim: OCI runtime create failed: container_linux.go:380: starting container process caused: exec: "uvicorn": executable file not found in $PATH: unknown

Here is the app.Dockerfile:

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FROM python:3.9 ARG POSTGRES_SERVER ENV APP_HOME=/home/app/web RUN mkdir -p $APP_HOME WORKDIR $APP_HOME RUN apk update && apk add --no-cache bash ADD requirements.txt $APP_HOME RUN pip install -r $APP_HOME/requirements.txt COPY src/ $APP_HOME CMD ["uvicorn", "app.main:app", "--reload", "--host", "0.0.0.0", "--port", "8080"]

Here is the Docker Compose configuration (app.yml):

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version: '3.7' services: nginx: env_file: .env build: context: . dockerfile: ./compose/local/nginx.Dockerfile restart: always ports: - "${EX_PORT_NGINX:-8030}:80" volumes: - ./nginx/site.conf:/etc/nginx/conf.d/default.conf core: env_file: .env build: context: . dockerfile: ./compose/local/app.Dockerfile args: POSTGRES_SERVER: ${POSTGRES_SERVER:-} restart: always volumes: - ./src:/home/app/web/ logging: driver: "json-file" options: max-size: "5m" max-file: "10"

This is the command I’m using to start the containers:

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docker-compose -f app.yml up -d

What is causing this issue and how do I fix it?

The Solution

The most likely cause of this error is that Uvicorn is not being installed in the Docker container. Make sure that your application’s requirements.txt file includes the following packages necessary to run FastAPI applications:

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fastapi uvicorn

Alternatively, these packages could be installed explicitly during the creation of the container.

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FROM python:3.9 ARG POSTGRES_SERVER ENV APP_HOME=/home/app/web RUN mkdir -p $APP_HOME WORKDIR $APP_HOME RUN apk update && apk add --no-cache bash ADD requirements.txt $APP_HOME RUN pip install -r $APP_HOME/requirements.txt # Install FastAPI and Uvicorn RUN pip install fastapi uvicorn COPY src/ $APP_HOME CMD ["uvicorn", "app.main:app", "--reload", "--host", "0.0.0.0", "--port", "8080"]

Including these packages in requirements.txt is the recommended approach, as that will enhance the application’s portability and prevent future errors of this nature.

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