Docker

Docker Container of Node.js web App

Short summary of the commands

Short

docker build -t rayalevinson/simpleweb .
OR
docker build -t rayalevinson/posts:0.0.1 .
docker run [image id or image tag]
docker run -it [image id or image tag] [cmd] [cmd] - overrides the default command
docker ps

docker exec -it [container id] [cmd]
docker logs [container id]

Option One

docker build -t rayalevinson/simpleweb .
docker run -p 5000:5000 rayalevinson/simpleweb
docker ps

docker exec -it sh
OR
winpty docker exec -it sh

Option Two

docker build .
Result: id of the image that was just built
docker run <id of the image>

Create project simpleweb

Create package.json

{
  "dependencies": {
    "express": "*"
  },
  "scripts": {
    "start": "node index.js"
  }
}

Create index.js

const express = require('express');

const app = express();

app.get('/', (req, res) => {
  res.send('Hi there');
});

const PORT = process.env.PORT || 5000;

app.listen(PORT, () => {
  console.log(`App started on port ${PORT}`);
});

Create Dockerfile

# Use and existing docker image as a base ===
# Specify a base image
FROM node:alpine

WORKDIR /usr/app

# Download and install a dependency ===
COPY ./package.json ./
RUN npm install
COPY ./ ./

# Tell the image what to do when it starts as a container ===
# Default command
CMD ["npm", "start"]

Create .dockerignore

  node_modules

docker build -t rayalevinson/simpleweb .
<-- -t is tag

Docker run with Port Mapping

docker run -p 5000:5000 rayalevinson/simpleweb

docker run -p <route incoming requests to this port on local host> <this port inside the container>

Run sh using docker exec

In the another terminal

docker ps

docker exec -it <container id> sh

winpty docker exec -it <container id> sh

-it is - attach STDIN and and a nice looking terminal into the shell

We enter into the /usr/app due to WORKDIR /usr/app in the Dockerfile

cd /

ls

will give a list of the folders

Open in the browser

http://localhost:5000

Specifying a working directory

docker run -it rayalevinson/simpleweb sh
<-- override the default set of commands by sh (shell)
OR
winpty docker run -it rayalevinson/simpleweb sh
Result of the copy command in the Dockerfile see by
ls
The problem with this approach that we may accidentally to override files or folders inside the container
Use:
WORKDIR /usr/app

Copy local files into file system inside the temporary container

copy ./ ./

copy <path to folder to copy from on my machine relative to build context> <place to copy stuff to inside the container> ===

copy <path to the current working folder of the project> <path to the current working folder inside the container>

See project # 285 /simpleweb