⚖️ Hello Balancers!

From cloud load to life load, you can balance it all! 🐘📦

📚 All code, docs, and resources are available in my GitHub repository:

In the last post,

⚖️ Cloud Load Balancing and Auto Scaling 📈

Madhurima Rawat ・ May 13

#cloud #tutorial #cloudcomputing #aws

Now, before we float too high in the clouds, let’s bring things down to earth and local.

In this post, we’ll set up a PostgreSQL database using Docker on your local machine.
It’s quick, clean, and the perfect way to prototype or develop cloud-ready apps without relying on live cloud resources.

No installations. No clutter. Just a few Docker commands and you're good to go. 🐳🧪

Let’s containerize our data journey from the ground up! 📦🔌

Cloud Databases and Data Management

Overview

This experiment covers setting up and managing cloud-based relational databases using PostgreSQL, Docker, and LocalStack. It provides hands-on experience with database management in a simulated cloud environment, replicating real-world cloud database operations using containerized solutions.

What are Databases?

Databases store, organize, and manage data efficiently. They are crucial in applications ranging from websites to large-scale enterprise systems.

Types of Databases

Databases are broadly categorized into:

• Relational Databases (SQL-based) – Structured data stored in tables (e.g., PostgreSQL, MySQL).
• NoSQL Databases – Flexible schema for handling unstructured data (e.g., MongoDB, Cassandra).
• Cloud Databases – Managed services with scalable storage (e.g., AWS RDS, Google Cloud Firestore).

PostgreSQL Features

PostgreSQL is a powerful, open-source relational database with features like:

• ACID Compliance – Ensures data integrity.
• Extensibility – Supports custom functions and data types.
• Scalability – Handles large volumes of data.

Real-World Application & Case Study

Use Case: Financial Data Management

A leading bank implemented PostgreSQL on the cloud to handle transaction processing, fraud detection, and real-time analytics. With Dockerized deployments, they achieved high availability, ensuring 99.9% uptime and enhanced security.

This experiment provides insights into deploying such systems using Docker and LocalStack to simulate real-world cloud database management.

🖼️ About the Cover Image:
It illustrates the journey of data in a cloud environment. On the left, a PostgreSQL database (🐘🗄️) stores structured information securely. That data flows into a brain (🧠), symbolizing the tools and technologies used for managing, querying, and analyzing the data, like Docker, pgAdmin, and SQL scripts. From there, the insights are transformed into visual representations, a pie chart (📊) and bar graph (📈) displayed on a blackboard (🧾), indicating how data is communicated, presented, and used for decision-making in cloud-native setups.

Database Operations with Postgres

1. Creating an RDS Instance Using LocalStack

Command:

aws rds create-db-instance --db-instance-identifier mydb \
  --db-instance-class db.t3.micro \
  --engine mysql \
  --master-username admin \
  --master-user-password password \
  --allocated-storage 20 \
  --endpoint-url=http://localhost:4566

Error Output:

Could not connect to the endpoint URL: "http://localhost:4566/"

An error occurred (InternalFailure) when calling the CreateDBInstance operation:
API for service 'rds' not yet implemented or pro feature - please check
https://docs.localstack.cloud/references/coverage/ for further information

Explanation:

• The command attempts to create an RDS instance in LocalStack.
• --endpoint-url=http://localhost:4566 → Uses LocalStack instead of AWS.
• Errors indicate:
  • LocalStack is either not running or misconfigured.
  • RDS API might not be fully implemented in the free version of LocalStack.

Output Breakdown:

• Could not connect to the endpoint URL → LocalStack might not be running or accessible.
• InternalFailure error → The RDS API might require LocalStack Pro for full functionality.

• Possible Fixes:

  • Ensure LocalStack is running:

  docker run --rm -d --name localstack_main -p 4566:4566 localstack/localstack
  

  • Check service coverage: LocalStack RDS Coverage

2. Starting a PostgreSQL Container

Command:

docker start my-postgres

docker start postgres

Error Output:

Error response from daemon: No such container: my-postgres
Error: failed to start containers: my-postgres

Error response from daemon: No such container: postgres
Error: failed to start containers: postgres

Explanation:

• The containers do not exist under the specified names.
• Verify running containers with:

  docker ps -a

• If needed, create a new container:

  docker run --name my-postgres -e POSTGRES_USER=admin \
    -e POSTGRES_PASSWORD=password -e POSTGRES_DB=mydb \
    -p 5432:5432 -d postgres:15

Output Breakdown:

• No such container: my-postgres → The container was never created or was removed.
• failed to start containers → The container name does not match any existing instances.
• Possible Fixes:
  • Check existing containers: docker ps -a
  • Create and start a new PostgreSQL container using docker run (above).

3. Listing Available Docker Images

Command:

docker images

Output:

| REPOSITORY            | TAG    | IMAGE ID     | CREATED      | SIZE   |
| --------------------- | ------ | ------------ | ------------ | ------ |
| my-flask-app          | latest | f5feae0ac7a4 | 6 hours ago  | 139MB  |
| flask-app             | latest | ae4054c49614 | 7 hours ago  | 139MB  |
| hackvortex-backend    | latest | 14e63c26d40b | 21 hours ago | 1.05GB |
| postgres              | 15     | e45d3f5ec589 | 7 days ago   | 430MB  |
| localstack/localstack | latest | b686f3948f42 | 6 weeks ago  | 1.18GB |
| python                | 3.9    | 9f98746e2033 | 3 months ago | 999MB  |
| nginx                 | latest | b52e0b094bc0 | 4 weeks ago  | 192MB  |

Explanation:

• Displays available images in the local Docker environment.
• PostgreSQL (postgres:15) is available.
• LocalStack (localstack/localstack) is present but needs verification (docker ps -a).

Output Breakdown:

• postgres:15 is listed → The image exists but the container may not be running.
• localstack/localstack exists → LocalStack is installed but may need to be started.

• Possible Fixes:

  • Start PostgreSQL if not running:

  docker run --name my-postgres -e POSTGRES_USER=admin \
    -e POSTGRES_PASSWORD=password -e POSTGRES_DB=mydb \
    -p 5432:5432 -d postgres:15
  

  • Ensure LocalStack is running:

  docker start localstack_main
  

4. Starting a PostgreSQL Container

Command:

C:\Users\rawat>docker start postgres

Error Output:

Error response from daemon: No such container: postgres
Error: failed to start containers: postgres

5. Listing All Containers

Command:

C:\Users\rawat>docker ps -a

Output:

6. Running a PostgreSQL Container

Command:

C:\Users\rawat>docker run --name my-postgres -e
POSTGRES_USER=admin -e POSTGRES_PASSWORD=password -e
POSTGRES_DB=mydb -p 5432:5432 -d postgres:15

Error Output:

docker: Error response from daemon: driver failed
programming external connectivity on endpoint my-postgres
(feae7f0fb87909bde1853a7ddefa49bb518f11250e54304f75109
68f7a88cca1): Bind for 0.0.0.0:5432 failed: port is already allocated.

7. Resolving Port Conflict and Running PostgreSQL on a Different Port

Command:

C:\Users\rawat>docker run --name my-new-postgres -e
POSTGRES_USER=admin -e POSTGRES_PASSWORD=password -e
POSTGRES_DB=mydb -p 5433:5432 -d postgres:15

Output:

b2efdca3c6f0af6cf4154fce236f0b66b5efba0f4f9e14972c94b3e0a5afa9de

8. Verifying Running Containers

Command:

C:\Users\rawat>docker ps

Output:

9. Connecting to PostgreSQL and Performing SQL Operations

Command:

C:\Users\rawat>docker exec -it my-
new-postgres psql -U admin -d mydb

Output:

psql (15.12 (Debian 15.12-1.pgdg120+1))
Type "help" for help.

Creating a Table and Inserting Data:

CREATE TABLE students (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    email VARCHAR(100) UNIQUE NOT NULL
);
INSERT INTO students (name, email) VALUES
('Alice Johnson', 'alice@example.com'),
('Bob Smith', 'bob@example.com'),
('Charlie Brown', 'charlie@example.com');

Output:

CREATE TABLE
INSERT 0 3

10. Performing SQL Queries

Selecting Data:

SELECT * FROM students;

Output:

Updating Data:

UPDATE students SET email = 'bob.smith@example.com'
WHERE name = 'Bob Smith';

Output:

UPDATE 1

Deleting Data:

DELETE FROM students WHERE name = 'Charlie Brown';

Output:

DELETE 1

Selecting Data with a Condition:

SELECT * FROM students WHERE name LIKE 'A%';

Output:

Exiting PostgreSQL:

\q

📄 Want to see how it all worked step by step? Check it out here:

🔗 Experiment 7 Output (PDF)

🧠 Curious about how each command runs and responds? See the detailed input-output flow here:

🖥️ PostgreSQL + Docker Setup Flow (PDF)

🎉 And that’s a wrap on Cloud Databases and Data Management!

💡 We went hands-on with setting up PostgreSQL using Docker, a clean, fast, and containerized way to build and test database-backed apps locally before going cloud-native.

💬 Tried other tools like MySQL, MongoDB, or hosted services like Firebase? I’d love to hear what worked best for you and why!

📚 Know a helpful resource or walkthrough?. I’d love to include helpful links in the article for others to explore!

🔥 Coming up next:
We're diving into Cloud Security: Identity and Access Management (IAM), the guardrails of modern cloud architecture. 🔐☁️
Let’s talk users, roles, policies, and how to keep your cloud castle secure!