---
title: Pre-seeding database with schema and data at startup for development environment
linktitle: Pre-seeding database  
description: &desc Pre-seeding database with schema and data at startup for development environment
keywords: Pre-seeding, database, postgres, container-supported development
summary: *desc
tags: [app-dev, databases]
params:
  time: 20 minutes
---

Pre-seeding databases with essential data and schema during local development is a common practice to enhance the development and testing workflow. By simulating real-world scenarios, this practice helps catch frontend issues early, ensures alignment between Database Administrators and Software Engineers, and facilitates smoother collaboration. Pre-seeding offers benefits like confident deployments, consistency across environments, and early issue detection, ultimately improving the overall development process.

In this guide, you will learn how to:

- Use Docker to launch up a Postgres container
- Pre-seed Postgres using a SQL script
- Pre-seed Postgres by copying SQL files into Docker image
- Pre-seed Postgres using JavaScript code

## Using Postgres with Docker

The [official Docker image for Postgres](https://hub.docker.com/_/postgres) provides a convenient way to run Postgres database on your development machine. A Postgres Docker image is a pre-configured environment that encapsulates the PostgreSQL database system. It's a self-contained unit, ready to run in a Docker container. By using this image, you can quickly and easily set up a Postgres instance without the need for manual configuration.

## Prerequisites

The following prerequisites are required to follow along with this how-to guide:

- [Docker Desktop](https://www.docker.com/products/docker-desktop/) 

## Launching Postgres

Launch a quick demo of Postgres by using the following steps:

1. Open the terminal and run the following command to start a Postgres container.

   This example will launch a Postgres container, expose port `5432` onto the host to let a native-running application to connect to it with the password `mysecretpassword`.

   ```console
   $ docker run -d --name postgres -p 5432:5432 -e POSTGRES_PASSWORD=mysecretpassword postgres
   ```

2. Verify that Postgres is up and running by selecting the container and checking the logs on Docker Dashboard.

   ```plaintext
   PostgreSQL Database directory appears to contain a database; Skipping initialization
 
   2024-09-08 09:09:47.136 UTC [1] LOG:  starting PostgreSQL 16.4 (Debian 16.4-1.pgdg120+1) on aarch64-unknown-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
   2024-09-08 09:09:47.137 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
   2024-09-08 09:09:47.137 UTC [1] LOG:  listening on IPv6 address "::", port 5432
   2024-09-08 09:09:47.139 UTC [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
   2024-09-08 09:09:47.142 UTC [29] LOG:  database system was shut down at 2024-09-08 09:07:09 UTC
   2024-09-08 09:09:47.148 UTC [1] LOG:  database system is ready to accept connections
   ```

3. Connect to Postgres from the local system.

   The `psql` is the PostgreSQL interactive shell that is used to connect to a Postgres database and let you start executing SQL commands. Assuming that you already have `psql` utility installed on your local system, it's time to connect to the Postgres database. Run the following command on your local terminal:

   ```console
   $ docker exec -it postgres psql -h localhost -U postgres
   ```

   You can now execute any SQL queries or commands you need within the `psql` prompt.

   Use `\q` or `\quit` to exit from the Postgres interactive shell.

## Pre-seed the Postgres database using a SQL script

Now that you've familiarized yourself with Postgres, it's time to see how to pre-seed it with sample data. In this demonstration, you'll first create a script that holds SQL commands. The script defines the database, and table structure and inserts sample data. Then you will connect the database to verify the data.