How To Use Docker Volumes for Persistent Knowledge Storage

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

Conditions

To observe together with this tutorial:

• You need to have Docker put in in your machine
• Try to be comfy 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 information. This quantity will persist the information 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/knowledge 
	-p 5432:5432 
	postgres

This command runs my_postgres in indifferent mode. Utilizing –v pg_data:/var/lib/postgresql/knowledge mounts the pg_data quantity to /var/lib/postgresql/knowledge 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 amount, we are able to confirm it’s getting used. You may examine the amount and test 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 may navigate to this listing and see the PostgreSQL knowledge recordsdata.

[
	{
    	"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

Connect 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:

Connect with the brand new database:

Create a desk and insert some knowledge:

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

INSERT INTO customers (identify, e-mail) VALUES ('Abby', '[email protected]'), ('Bob', '[email protected]');

Run a pattern question:

Output:

 id | identify |  	e-mail  	 
----+------+------------------
  1 | Abby | [email protected]
  2 | Bob  | [email protected]

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 information persists even when the container is stopped.

$ docker cease my_postgres
$ docker rm my_postgres

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

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

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

Connect with the Postgres occasion and confirm that the information persists.

Open a psql session:

$ docker exec -it my_postgres psql -U postgres

Connect with the mydb database:

Confirm the information within the customers desk:

You need to nonetheless see the output:

 id | identify |  	e-mail  	 
----+------+------------------
  1 | Abby | [email protected]
  2 | Bob  | [email protected]

I hope this tutorial helps you perceive find out how to use volumes to persists knowledge when working with Docker.

Further Sources

To be taught 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, knowledge science, and content material creation. Her areas of curiosity and experience embody DevOps, knowledge science, and pure language processing. She enjoys studying, writing, coding, and occasional! At the moment, 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.