How To Use Docker Volumes for Persistent Knowledge Storage

When utilizing Docker, you should utilize volumes to persist information even while you cease or restart the containers. We’ll create and use Docker volumes for PostgreSQL.

Conditions

To observe together with this tutorial:

• It is best to have Docker put in in your machine
• Try to be snug with Docker instructions and PostgreSQL

Step 1: Pull the PostgreSQL Picture

First, we pull the PostgreSQL picture from DockerHub:

Step 2: Create a Docker Quantity

Subsequent, let’s create a Docker quantity to retailer the info. This quantity will persist the info even when the container is eliminated.

$ docker quantity create pg_data

Step 3: Run the PostgreSQL Container

Now that we’ve pulled the picture and created a quantity, we are able to run the PostgreSQL container attaching the created quantity to it.

$ docker run -d 
	--name my_postgres 
	-e POSTGRES_PASSWORD=mysecretpassword 
	-v pg_data:/var/lib/postgresql/information 
	-p 5432:5432 
	postgres

This command runs my_postgres in indifferent mode. Utilizing –v pg_data:/var/lib/postgresql/information mounts the pg_data quantity to /var/lib/postgresql/information within the container. And utilizing -p 5432:5432 maps port 5432 of my_postgres to port 5432 on the host machine.

Step 4: Confirm the Quantity Utilization

Now that we’ve created the quantity, we are able to confirm it’s getting used. You possibly can examine the quantity and verify the contents.

$ docker quantity examine pgdata

Working this command will present particulars in regards to the quantity, together with its mount level in your host system. You possibly can navigate to this listing and see the PostgreSQL information information.

[
	{
    	"CreatedAt": "2024-08-07T15:53:23+05:30",
    	"Driver": "local",
    	"Labels": null,
    	"Mountpoint": "/var/lib/docker/volumes/pg_data/_data",
    	"Name": "pg_data",
    	"Options": null,
    	"Scope": "local"
	}
]

Step 5: Create a Database and Desk

Hook up with the Postgres occasion and create a database and desk.

Begin a psql session:

$ docker exec -it my_postgres psql -U postgres

Create a brand new database:

Hook up with the brand new database:

Create a desk and insert some information:

CREATE TABLE customers (
    id SERIAL PRIMARY KEY,
    identify VARCHAR(100),
    e mail VARCHAR(100)
);

INSERT INTO customers (identify, e mail) VALUES ('Abby', 'abby@instance.com'), ('Bob', 'bob@instance.com');

Run a pattern question:

Output:

 id | identify |  	e mail  	 
----+------+------------------
  1 | Abby | abby@instance.com
  2 | Bob  | bob@instance.com

Step 6: Cease and Take away the Container

Cease the working container and take away it. We do that so we are able to take a look at that the info persists even when the container is stopped.

$ docker cease my_postgres
$ docker rm my_postgres

Step 7: Re-run the Postgres Container with the Similar Quantity

Begin a brand new PostgreSQL container with the identical quantity to make sure information persistence.

$ docker run -d 
	--name my_postgres 
	-e POSTGRES_PASSWORD=mysecretpassword 
	-v pgdata:/var/lib/postgresql/information 
	-p 5432:5432 
	postgres

Hook up with the Postgres occasion and confirm that the info persists.

Open a psql session:

$ docker exec -it my_postgres psql -U postgres

Hook up with the mydb database:

Confirm the info within the customers desk:

It is best to nonetheless see the output:

 id | identify |  	e mail  	 
----+------+------------------
  1 | Abby | abby@instance.com
  2 | Bob  | bob@instance.com

I hope this tutorial helps you perceive the best way to use volumes to persists information when working with Docker.

Extra Sources

To study extra, learn the next sources:

Completely satisfied exploring!

Bala Priya C is a developer and technical author from India. She likes working on the intersection of math, programming, information science, and content material creation. Her areas of curiosity and experience embrace DevOps, information science, and pure language processing. She enjoys studying, writing, coding, and low! At present, she’s engaged on studying and sharing her data with the developer group by authoring tutorials, how-to guides, opinion items, and extra. Bala additionally creates partaking useful resource overviews and coding tutorials.