Docker compose run yarn install

Question

When running the step RUN yarn install in a Dockerfile during docker-compose build command, I get:

[1/4] Resolving packages... [2/4] Fetching packages... info [email protected]: The platform "linux" is incompatible with this module. info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation. [3/4] Linking dependencies... warning "@rails/webpacker > [email protected]" has unmet peer dependency "caniuse-lite@^1.0.30000697". warning " > [email protected]" has unmet peer dependency "webpack@^2.2.0 || ^3.0.0". warning "webpack-dev-server > [email protected]" has unmet peer dependency "webpack@^1.0.0 || ^2.0.0 || ^3.0.0". [4/4] Building fresh packages...

but the node_modules folder is NOT created. On the other hand when I run

docker-compose run SERVICE_NAME yarn install

I get:

[1/4] Resolving packages... [2/4] Fetching packages... info [email protected]: The platform "linux" is incompatible with this module. info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation. [3/4] Linking dependencies... warning "@rails/webpacker > [email protected]" has unmet peer dependency "caniuse-lite@^1.0.30000697". warning " > [email protected]" has unmet peer dependency "webpack@^2.2.0 || ^3.0.0". warning "webpack-dev-server > [email protected]" has unmet peer dependency "webpack@^1.0.0 || ^2.0.0 || ^3.0.0". [4/4] Building fresh packages...

but then the folder node_modules IT IS created in the project folder.

I just don't understand why ... I'm expecting same functionality but I'm missing something.

Here my docker-compose service

services:
  ruby:
    build:
      context: .
      dockerfile: docker/ruby/Dockerfile
    networks:
      - some-network
    volumes:
      - .:/app
    ports:
      - "3000:3000"
    depends_on:
      - mysql
    command: bundle exec rails s -p 3000 -b '0.0.0.0'

Dockerfile

FROM ruby:2.5

# Install dependencies:
# - build-essential: To ensure certain gems can be compiled
# - nodejs: Compile assets
# - npm: Install node modules
# - yarn: Install & manage node modules [should make npm obsolete]
# - libpq-dev
RUN curl -sL https://deb.nodesource.com/setup_8.x | bash - && \
    curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
    echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
    apt-get update && \
    apt-get install -qq -y build-essential nodejs yarn \
    libpq-dev \
    mysql-client 

RUN mkdir /app
COPY . /app

WORKDIR /app

# install node dependencies
RUN yarn install

RUN bundle install

Answer 1

At first creates an image depending on Dockerfile:

1. Get an image ruby:2.5 to create new image from it
2. Install all dependencies
3. Create folder /app
4. Copy all files from your system (project directory) to image's /app path
5. Install yarn and bundle (call methods inside image)

And after that "mounts" your projects folder to image's /app folder, so it becomes same as your system root folder. After that "generates" container and executes CMD command from Docker file (if exists).

Take an account that this is not detailed explanation of image/container generation flow, but hope it can help you to solve your problem. So you can

1. Run your code directly from container (as you done in Dockerfile)
2. or Don't copy source code to container and mount code as volume (as you done in docker-compose.yml), and execute yarn install in your system, or create entrypoint script with installation commands: entrypoint: ./entrypoint.sh

EXAMPLE OF FILES

If you want to update your source files "on fly" (to see updates without rebuilding container), you must use second way.

Create file run.sh in your project directory:

run.sh

#!/bin/sh

echo '--- run yarn install'
yarn install

echo '--- run bundle install'
bundle install

# HERE YOU CAN RUN ANY OTHER SCRIPT BEFORE CONTAINER BUILDING

echo '--- create docker image and up it'
sudo docker-compose up -d --build

docker-compose.yml

No need to change (keep like in your question).

Dockerfile

FROM ruby:2.5

# Install dependencies:
# - build-essential: To ensure certain gems can be compiled
# - nodejs: Compile assets
# - npm: Install node modules
# - yarn: Install & manage node modules [should make npm obsolete]
# - libpq-dev
RUN curl -sL https://deb.nodesource.com/setup_8.x | bash - && \
    curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
    echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
    apt-get update && \
    apt-get install -qq -y build-essential nodejs yarn \
    libpq-dev \
    mysql-client 

WORKDIR /app

To build and up container just run command: sh run.sh

It will install node dependencies in your system, after that will create container, which /app folder will be your project folder (in your system), so your code changes will take an effect immediately.