Back‐end Develop Guide

Back-end Develop Guide

TODO: put in general guidelines for back-end

Quick Summary of Docker Containers vs Images

Docker Image

• An image is a lightweight, standalone, and executable package that includes everything needed to run a piece of software, including the code, runtime, libraries, and system tools.
• It is a static snapshot of a file system, and it is built from a set of instructions called a Dockerfile.
• Images are used as a template to create containers.

Docker Container

• A container is a running instance of a Docker image.
• It encapsulates an application and its dependencies, isolating it from the host system and other containers.
• Containers are portable and can run consistently across different environments, thanks to the encapsulated nature of Docker images.

Key Differences between Images and Containers

Stateless vs. Stateful

• Images are stateless and immutable. Once built, they don't change.
• Containers are a running, writable instance of an image. They are stateful, as they can have data and configurations that change during runtime.

Build vs. Runtime

• Images are built-time constructs. You create or update them by writing a Dockerfile and running the docker build command.
• Containers are runtime entities. They are created from images and run using the docker run command.

Purpose

• Images are used for distribution and deployment. They serve as a blueprint for creating containers.
• Containers are the execution environment for a specific application and its dependencies.

Container Repositories

Like Github repositories, Docker also has a repository but we do not upload images to the repository when we are developing.

Working on GLADOS

Docker Containers and Images

There are four docker containers (glados-backend, glados-frontend, glados-mongodb, glados-DEVONLY-mongodb-express) and four docker images (glados-project-app-backend, glados-project-app-frontend, mongo, mongo-express).

DockerFile

Once you make changes to your DockerFile (which is backend.Dockerfile), you need to rebuild the docker image.

Locate MonoRepo/apps/backend and execute this command:

docker build -t glados-project-app-backend:latest -f backend.Dockerfile .

Check if the images are up to date: docker images

If you created a wrong image, if you want to remove an image: docker image rm (id of the image)

Accessing Docker Container

There are three ways to access the running docker container:

Let's say if you want to access glados-backend container, then we can execute one of the three commands below:

docker exec -it glados-backend //bin/bash

docker exec -it glados-backend sh

docker exec -it glados-backend //bin/sh