When I use docker-compose up the container exits with code 10 and says Could not locate Gemfile or .bundle/ directory

but if I do docker run web entrypoint.sh The rails app seems to start without an issue.

What could be the cause of this inconsistent behavior?

Entrypoint.sh

#!/bin/bash

set -e

if [ -f tmp/pids/server.pid ]; then
    rm tmp/pids/server.pid
fi

bundle exec rails s -b 0.0.0.0 -p 8080

Relevant part from the docker-compose file.

docker-compose.yml

...
  web:
    build:
      context: "./api/" 
      args:
        RUBY_VERSION: '2.7.2'
        BUNDLER_VERSION: '2.2.29'
    entrypoint: entrypoint.sh
    volumes:
      - .:/app
    tty: true
    stdin_open: true
    ports:
      - "8080:8080"
    environment:
      - RAILS_ENV=development
    depends_on:
      - mongodb
...

CodePudding user response：

When you docker run web ..., you're running exactly what's in the image, no more and no less. On the other hand, the volumes: directive in the docker-compose.yml file replaces the container's /app directory with arbitrary content from the host. If your Dockerfile RUN bundle install expecting to put content in /app/vendor in the image, the volumes: hide that.

You can frequently resolve problems like this by deleting volumes: from the Compose setup. Since you're running the code that's built into your image, this also means you're running the exact same image and environment you'll eventually run in production, which is a big benefit of using Docker here.

(You should also be able to delete the tty: and stdin_open: options, which aren't usually necessary, and the entrypoint: and those specific build: { args: }, which replicate settings that should be in the Dockerfile.)

(The Compose file suggests you're building a Docker image out of the api subdirectory, but then bind-mounting the current directory . -- api's parent directory -- over the image contents. That's probably the immediate cause of the inconsistency you see.)