Environment variable

docker run -e ХУВЬСАГЧИЙН_НЭР=утга image_name

docker run -d \
  --name postgres \
  -e POSTGRES_PASSWORD=secret123 \
  -e POSTGRES_USER=admin \
  -e POSTGRES_DB=mydb \
  postgres:16

docker run -d \
  --name myapp \
  -e NODE_ENV=production \
  -e PORT=3000 \
  -e API_KEY=abc123xyz \
  -p 3000:3000 \
  myapp:1.0

const port = process.env.PORT || 3000;
const env = process.env.NODE_ENV || "development";
const apiKey = process.env.API_KEY;

console.log(`${env} орчинд ${port} port дээр ажиллаж байна`);

NODE_ENV=production
PORT=3000
DB_HOST=db
DB_PORT=5432
DB_NAME=mydb
DB_USER=admin
DB_PASSWORD=secret123
JWT_SECRET=verylongsecretkey
API_URL=https://api.example.com

docker run -d \
  --name myapp \
  --env-file .env \
  -p 3000:3000 \
  myapp:1.0

# .gitignore
.env
.env.local
.env.production

FROM node:20-alpine

WORKDIR /app

# Анхдагч утгатай environment variable
ENV NODE_ENV=production
ENV PORT=3000
ENV LOG_LEVEL=info

COPY package*.json ./
RUN npm install --omit=dev
COPY . .

EXPOSE ${PORT}
CMD ["node", "index.js"]

# NODE_ENV=development болно (Dockerfile-ийн production-г дарна)
docker run -e NODE_ENV=development myapp

# ARG — зөвхөн build явцад байна
ARG BUILD_DATE
ARG GIT_COMMIT

# ENV — build ба runtime хоёуланд байна
ENV APP_VERSION=1.0.0
ENV BUILD_DATE=${BUILD_DATE}

docker build \
  --build-arg BUILD_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ) \
  --build-arg GIT_COMMIT=$(git rev-parse --short HEAD) \
  -t myapp:1.0 .

# Тодорхой container-ийн env var жагсаах
docker exec myapp env

# Нэг хувьсагч харах
docker exec myapp printenv NODE_ENV

# docker inspect-д харуулах
docker inspect myapp | grep -A 20 '"Env"'

NODE_ENV=production
PORT=3000
DB_HOST=db
PATH=/usr/local/sbin:/usr/local/bin:...

ENV DB_PASSWORD=secret123  # Image-д хадгалагдана, аюултай!

docker run -e DB_PASSWORD=secret123 myapp

docker run --env-file .env.production myapp

const { Pool } = require("pg");

const pool = new Pool({
  host: process.env.DB_HOST || "localhost",
  port: parseInt(process.env.DB_PORT || "5432"),
  database: process.env.DB_NAME || "mydb",
  user: process.env.DB_USER || "postgres",
  password: process.env.DB_PASSWORD,
});

const port = parseInt(process.env.PORT || "3000");

// HTTP server...

PORT=3000
DB_HOST=postgres
DB_PORT=5432
DB_NAME=mydb
DB_USER=admin
DB_PASSWORD=supersecret

# PostgreSQL
docker run -d \
  --name postgres \
  --network mynet \
  -e POSTGRES_DB=mydb \
  -e POSTGRES_USER=admin \
  -e POSTGRES_PASSWORD=supersecret \
  postgres:16

# Node.js апп
docker run -d \
  --name nodeapp \
  --network mynet \
  --env-file .env \
  -p 3000:3000 \
  nodeapp:1.0

# Тайлбар мөр
KEY=value

# Хоосон зай байхгүй байх
KEY=value          # ✓
KEY = value        # ✗ (хоосон зайтай)

# Хашилт шаардлагагүй (гэхдээ зөвшөөрнө)
KEY=hello world    # ✓
KEY="hello world"  # ✓

# Хоосон утга
KEY=              # Хоосон мөр

# Тусгай тэмдэгт агуулсан утга
PASSWORD="p@ss#w0rd!"

services:
  app:
    image: myapp:1.0
    environment:
      - NODE_ENV=production
      - PORT=3000
    env_file:
      - .env

  db:
    image: postgres:16
    environment:
      POSTGRES_PASSWORD: ${DB_PASSWORD} # .env файлаас авна
      POSTGRES_DB: ${DB_NAME}