Docker commands with nodejs examples | Dev Tools

Why we use docker?

Docker is a platform that allows developers to easily create, deploy, and run applications in a containerized environment. Containers are a way of packaging software in a way that makes it easy to move from development to production.

Docker provides several advantages over traditional virtualization methods, such as:

1. Portability: Containers can run on any system that supports Docker, making it easy to move applications between different environments.
2. Consistency: Containers ensure that the environment in which the application runs is consistent, regardless of where it is deployed.
3. Isolation: Containers allow multiple applications to run on the same system without interfering with each other.
4. Scalability: Containers can be easily scaled up or down to meet the demands of the application.
5. Lightweight: Containers use fewer resources than traditional virtualization methods, making them more efficient and cost-effective.
6. Versioning: Docker allows to version control your containers and rollback if something goes wrong.
7. Easy deployment: Docker container can be deployed on any platform that supports Docker, including on-premises, cloud, and hybrid environments.

Overall, Docker allows developers to create and deploy applications more efficiently and with greater consistency, making it an increasingly popular tool in the software development industry.

Docker useful commands:-

Here are some useful Docker commands for managing and interacting with containers:

1. docker run: This command is used to run a new container from a specified image.
2. docker start: This command starts a container that has been created but is not running.
3. docker stop: This command stops a running container.
4. docker rm: This command removes a stopped container.
5. docker ps: This command lists all running containers.
6. docker logs: This command shows the logs of a container.
7. docker inspect: This command provides detailed information about a container, including its configuration, network settings, and storage.
8. docker exec: This command allows you to run a command inside a running container.
9. docker images: This command lists all images on the local system.
10. docker pull: This command downloads an image from a registry.
11. docker push: This command pushes an image to a registry.
12. docker build: This command builds an image from a Dockerfile.
13. docker tag: This command tags an image with a repository name and a tag.
14. docker network: This command allows you to create and manage networks for connecting containers.
15. docker volume: This command allows you to create and manage volumes for persisting data.

These are some of the most commonly used Docker commands, but there are many more available for different tasks.

how to run nodejs app using docker?

Here are the general steps to run a Node.js application using Docker:

1. Create a Dockerfile in the root of your Node.js application. The Dockerfile is used to specify the base image and any additional dependencies that your application needs.
2. In the Dockerfile, specify the base image for your application. For a Node.js application, you can use the official Node.js image from Docker Hub.

FROM node:latest

1. In the Dockerfile, specify any additional dependencies that your application needs. For example, if your application uses a specific version of Node.js, you can specify that version.

FROM node:14

1. In the Dockerfile, copy the application code into the container.

COPY . /app

1. In the Dockerfile, specify the working directory for the application.

WORKDIR /app

1. In the Dockerfile, install the application's dependencies.

RUN npm install

1. In the Dockerfile, specify the command to start the application.

CMD ["npm", "start"]

1. Build the Docker image from the Dockerfile using the command docker build -t <image-name> .
2. Run the application by starting a container from the image using the command docker run -p 3000:3000 <image-name>

This will start the application and make it available on port 3000 of the host machine.

You can also use other options and flags to configure your container, like mapping volumes, setting environment variables, etc. Please refer to the official documentation for more information.

Please note that this is a general guide, and the exact steps may vary depending on the specifics of your Node.js application.

Docker Compose is a tool for defining and running multi-container Docker applications. It allows developers to define a set of containers, their configuration, and how they interact with each other in a single docker-compose.yml file. With Compose, you can start and stop the entire application with a single command, rather than starting and stopping each container individually.

Here is an example of a docker-compose.yml file for a Node.js application:

version: '3'

services:

  web:

    build: .

    ports:

      - "3000:3000"

    volumes:

      - .:/app

    command: npm start

This file defines a single service called "web" that is built from the current directory, maps port 3000 on the host to port 3000 in the container, and mounts the current directory as a volume in the container. The service will run the command npm start when started.

To start the application defined in this file, you can use the command docker-compose up. To stop the application, you can use the command docker-compose down.

Docker Compose also allows you to scale up or down the number of containers for a service, and you can use the command docker-compose scale service-name=number-of-containers.

You can also use the command docker-compose ps to see the status of all the services defined in the compose file, and docker-compose logs to see the logs of the services.

Docker Compose is particularly useful when you have multiple services that depend on each other and need to be run together. It simplifies the process of starting and stopping the application and allows for easy scaling and management of the application.