Docker setup for NestJS applications

.dockerignore

# just adding the .env.local file for
# my local development purposes and
# I do not really need to specify 
# every single file to be ignored 
# because I am not copying everything
# with "COPY . ." command
# you can see what I mean below
# in "Dockerfile"
.env.local*

.env

PORT=8080

docker-compose.yml

version: "3.7"

services:
  app:
    build:
      # referencing to ./Dockerfile
      context: .
    volumes:
      # mirroring only my local ./src directory
      # into the container's so every change
      # I have made locally will be applied
      # inside the container too
      - ./src:/app/src
    ports:
      # exposing node.js debugging port
      # so I can debug the application with
      # my IDE inside container
      - 9229:9229
      # exposing http port so I can access the
      # application outside of the container
      - ${PORT}:${PORT}
    command: npm run start:dev

Dockerfile

# fetching LTS node.js image
FROM node:lts-alpine

# setting cwd to /app
# we will mirror the project structure to
# the /app directory inside container
WORKDIR /app

# copying package files before npm install
# this part should be seperated to help
# docker to cache "npm i" command
COPY package*.json ./

# no need to explain i guess
RUN npm i

# copying the rest of the sources
# that is required by the application
# instead of this, you can simply run:
# COPY . .
# but, I just do not want to fill either 
# the container and the .dockerignore
# with redundant stuff
COPY src ./src
COPY .env* ./
COPY nest-cli.json ./
COPY tsconfig*.json ./

# finally running build before
# starting the application
RUN npm run build

# again, no need to explain
CMD ['npm', 'start']