Docker

• Docker is a software framework for building, running, and managing containers on servers and the cloud.
• Docker is a powerful tool used for developing, packaging, and deploying applications efficiently.
• It reduces your delay between writing code and running it in production. You can create self-contained environments known as containers. That can run consistently on different platforms.
• You need to install the Docker engine on your computer or device. The Docker engine allows you to create and manage docker containers, docker images, docker hub, docker desktop, etc.

Docker Installation on Ubuntu

• sudo apt-get update
• sudo apt install docker.io
• sudo systemctl enable dockerstart docker.
• sudo docker run hello-world to test if installation is done correctly, "Hello from Docker" should be printed.
• docker --help get commands used

Common Commands:

run Create and run a new container from an image
exec Execute a command in a running container
ps List containers
build Build an image from a Dockerfile
pull Download an image from a registry
push Upload an image to a registry
images List images
login Log in to a registry
logout Log out from a registry
search Search Docker Hub for images
version Show the Docker version information
info Display system-wide information

Running Postgres on Docker container

• sudo docker login Login with your Docker ID to push and pull images from Docker Hub.

• docker pull postgres:alpine download image for postgres (alpine version).

• sudo docker images list all images present.

• sudo docker run --name postgres-0 -e POSTGRES_PASSWORD=password -d -p 5432:5432 postgres:alpine running postgres container on default port (with password 'password').

• docker run --name postgres11 -e POSTGRES_PASSWORD=password -d -p 5432:5432 postgres

• sudo docker ps list containers (you can see postgres-0 running).

• sudo docker exec -it postgres-0 bash this command will let you get inside the actual container. exec means interact inside postgres-0 using bash command.

• pwd get inside root folder

• ls get file structure

• psql -U postgres -U for user name ('postgress' has root access).

• \du to see user

• create database test; create database

• \l show all databases

• \c test connect to 'test' database

• \d get relations

• sudo docker stop CONTAINER_ID stop the container by viewing container id from docker ps.

• sudo docker rm CONTAINER_ID remove that container (do it before creating a container with same name.)

• sudo docker start 3e27 start an exited (stopped) container.

• sudo service redis-server stop command to stop locally installed redis.

Connect the container running postgres image to Local Machine

• psql -h localhost -p 5432 -U postgrers get you inside of that instance running postgres.
• \q to quit out of this.

Running Redis on Docker container

• sudo docker pull redis pull redis image form docker hub. no version specified means default latest version
• sudo docker run --name redis01 -d redis -d means run it in demon mode (in background)
• sudo docker exec -it 3e27 sh execute redis container. sh means shell, -it means run it in interactive mode, 3e27 is container ids 1st 4 letters.
• sudo docker run --name redis02 -v redis.conf:/usr/local/etc/redis/redis.conf -d redis in order to use a specific config file, we have to map a value. the file in left hand side is our config file and the file in the right hand side is redis config file inside the container.

Explanation of run command

sudo docker run --name redis01 -p 6379:6379 -d redis

• sudo: This command runs the following Docker command with superuser (administrator) privileges. It's often required to execute Docker commands, especially on systems where Docker needs elevated permissions to create and manage containers.

• docker: This is the Docker command-line client that allows you to interact with Docker. It's the primary command to manage Docker containers, images, networks, and volumes.

• run: This command creates and starts a new container from a specified Docker image. If the image is not available locally, Docker will pull it from the Docker Hub or another configured Docker registry.

• --name redis01: This option assigns a custom name to the container, in this case, redis01. Naming containers makes it easier to manage and reference them later (e.g., for stopping, starting, or inspecting them). Without this option, Docker would assign a random name.

• -p 6379:6379: This option publishes a container's port to the host. The format is hostPort:containerPort. Here's what each part means:

• 6379 (first part): The port number on the host machine. This is the port you will use to access the Redis server from outside the container (e.g., from your Java application or other tools).

• 6379 (second part): The port number inside the container where the Redis server is listening. By default, Redis listens on port 6379 inside the container. This option maps port 6379 on your host machine to port 6379 inside the container, allowing external access to Redis running inside the container.

• -d: This option runs the container in detached mode, meaning the container runs in the background. If you omit this option, the container will run in the foreground, and you will see its logs and output in your terminal.

• redis: This is the name of the Docker image to use for the container. If the redis image is not already available on your local system, Docker will automatically pull it from Docker Hub, the default public registry.

Connection options: -h, --host=HOSTNAME database server host or socket directory (default: "local socket") -p, --port=PORT database server port (default: "5432") -U, --username=USERNAME database user name (default: "root") -w, --no-password never prompt for password -W, --password force password prompt (should happen automatically)