Docker

Introduction

Run the container in background:

docker container run --name xuxa --publish 80:80 nginx --detach

List containers:

docker container ls -a

Stop:

docker stop xuxa 

Remove container:

docker container rm -f 6666

Processes in the container:

docker top xuxa

Environment variable:

docker container run -d -p 3306:3306 --name db -e MYSQL_RANDOM_ROOT_PASSWORD=yes mysql

See what’s going on

• -it to enter the container:

docker container run -it --name proxy nginx bash

• exec for an existing container

Which port is mapped:

docker container port xuxa

From the terminal

pgcli -h localhost -p 5432 -U rio_perform rio_perform

Clean everything (dangerous)

docker kill $(docker ps -q) && docker rm $(docker ps -a -q) && docker volume rm -f $(docker volume ls -f dangling=true -q)

Images

Build from an official Nginx image; it will serve your index.html from the container root: Dockerfile

FROM nginx:latest
WORKDIR /usr/share/nginx/html
COPY index.html index.html

Build and run

docker image build -t nginx-with-html .
docker run -d -p 8080:80 nginx-with-html

Dockerfile

It will only run npm i if package.json changes. If you change project resources, you don’t need to reinstall. Dockerfile has no --watch by default.

Network

There are 3 types:

• host: host network
• bridge: only between containers
• none: no network

Example:

docker run --rm --net none alpine ash -c "ifconfig"

This starts alpine, removes it after exit (--rm), with no network access. The first command runs in ash (lightweight) via -c.

docker-compose

When using docker-compose, services can freely reach each other—no need to expose ports internally.

To rebuild after changes:

docker-compose up -d --build

To see processes managed by docker-compose (run inside the compose directory):

docker-compose ps

Example docker-compose.yml:

version: '3'
services:
  db:
    image: mongo:3.4
  backend:
    image: node:8.1
    volumes:
      - ./backend:/backend
    ports:
      - 3000:3000
    command: bash -c "cd /backend && npm i && node app"
  frontend:
    image: nginx:1.13
    volumes:
      - ./frontend:/usr/share/nginx/html/
    ports:
      - 80:80

Attach inside docker-compose:

docker-compose exec db psql -U postgress -d email_sender -c 'select * from email'

Local Dev

By default Docker does not have watch mode; volume mounts (-v) replicate changes from host to container. The volume -v /app/node_modules prevents the second volume mapping from replacing the container’s node_modules with the host’s (which might be empty). It keeps the layer from the build stage.