Docker helpful commands

What is Docker?

Docker allows you to package an application with its environment and all of its dependencies into a “box”, called a container. Usually, a container consists of an application running in a stripped-to-basics version of a Linux operating system. An image is a blueprint for a container, a container is a running instance of an image.

Helpful commands

Example Dockerfile :-

FROM node:16

# Create app directory
WORKDIR /usr/src/app

# Install app dependencies
# A wildcard is used to ensure both package.json AND package-lock.json are copied
# where available (npm@5+)
COPY package*.json ./

RUN npm install
# If you are building your code for production
# RUN npm ci --only=production

# Bundle app source
COPY . .

EXPOSE 8080
CMD [ "node", "server.js" ]

Create a .dockerignore file in the same directory as your Dockerfile with following content:

node_modules
npm-debug.log

This will prevent your local modules and debug logs from being copied onto your Docker image and possibly overwriting modules installed within your image.

Building your image

Now we will be building our image, -t flag allows you to tag your image, to be accessed later

docker build . -t <your app name>

View your image

The command below displays all the docker images being built till now:-

docker images

Run the image

We will be running our image now using the run command with -p flag which redirects a public port to private port inside the container and -d flag that runs the container in detached mode.

docker run -p 49160:8080 -d <your app name>

View running containers

docker ps -a

Log output of a running container

docker logs <container id>

SSH inside the container

docker exec -it <container id> /bin/bash

Build Docker image forcefully

docker build --no-cache -t <you app name>

Stop a Docker container

docker stop <container id>

Remove a Docker container

docker rm <container id>