PART 1 — Amazon RDS (Relational Database Service)
1. What is RDS?
Amazon RDS is a managed relational database service.
Instead of installing MySQL/PostgreSQL on EC2 manually, AWS manages:
- OS patching
- Backups
- Failover
- Monitoring
- Scaling
Supported engines:
- MySQL
- PostgreSQL
- MariaDB
- Oracle
- SQL Server
2. Why We Need RDS (Instead of EC2 + MySQL)
If you install DB on EC2:
- You manage OS
- You manage backups
- You configure replication
- You handle crashes
- You configure monitoring
- You secure everything
With RDS:
- AWS manages infrastructure
- You manage database logic
DevOps benefit:
- Less operational overhead
- Faster deployment
- Built-in HA
- Automated backups
- Easy scaling
3. RDS Lab
Goal:
Create MySQL RDS and connect from EC2.
Step 1 — Create RDS MySQL
AWS Console → RDS → Create Database
Choose:
- Standard Create
- Engine: MySQL
- Version: latest
- Templates: Free tier
Settings:
- DB instance identifier: devops-mysql
- Username: admin
- Password: StrongPassword123
Instance:
- db.t3.micro
Storage:
- 20 GB (default)
Connectivity:
- Same VPC as EC2
- Public access: NO
- Create new security group
Create database.
Wait 5–10 minutes.
Step 2 — Allow EC2 Access
Go to:
RDS → Security Group
Add inbound rule:
- Type: MySQL
- Port: 3306
- Source: EC2 security group
Why:
RDS is inside VPC and needs permission.
Step 3 — Connect from EC2
SSH into EC2:
Install MySQL client:
sudo apt update
sudo apt install mysql-client -y
Connect:
mysql -h <RDS-ENDPOINT> -u admin -p
Demonstrate:
- Create database
- Create table
- Insert data
- Select data
we will do together:
- Stop EC2 → RDS still works
- RDS automatic backup section
- Multi-AZ option
- Performance insights
DevOps Talking Points
- CI/CD apps connect to RDS
- Terraform creates RDS
- Monitoring with CloudWatch
- Secret Manager for DB password
- Blue/Green DB deployments
PART 2 — Amazon Aurora
1. What is Aurora?
Aurora is AWS’s high-performance database engine compatible with:
- MySQL
- PostgreSQL
It is:
- Faster than MySQL on RDS
- More scalable
- Auto-replicating
Why Aurora is Special
- 6 copies of data across 3 AZs
- Auto failover in seconds
- Read replicas automatically
- Storage auto-scales to 128TB
DevOps benefit:
- Enterprise-grade HA
- Massive scaling
- Read-heavy applications
- SaaS applications
Aurora Lab
Step 1 — Create Aurora MySQL
RDS → Create Database
Choose:
- Amazon Aurora
- Aurora MySQL-Compatible
Template:
- Dev/Test
Instance:
- db.t3.medium
Connectivity:
- Same VPC
Create.
Step 2 — Observe Architecture
Go to cluster view.
Explain:
- Writer endpoint
- Reader endpoint
- Replicas
Demonstrate:
- Add read replica
- Observe endpoints
Step 3 — Failover Demo
Reboot primary instance.
Show:
- Failover happens automatically
- Minimal downtime
Explain:
Traditional MySQL on EC2 cannot do this easily.
DevOps Use Cases
- High traffic applications
- Banking systems
- SaaS multi-tenant apps
- Large-scale Kubernetes applications
PART 3 — Amazon ElastiCache
1. What is ElastiCache?
It is managed Redis or Memcached.
Used for:
- Caching
- Session storage
- Fast lookups
- Reducing DB load
Why We Need Cache
Without cache:
App → Database every time
With cache:
App → Redis → Database only if needed
Result:
- Faster response
- Lower DB load
- Lower cost
Redis Lab
Step 1 — Create ElastiCache Redis
AWS Console → ElastiCache
Create:
- Redis
- Cluster mode disabled
- t3.micro
- Same VPC
Wait to create.
Step 2 — Allow EC2 Access
Modify security group:
- Port 6379
- Source: EC2 SG
Step 3 — Install Redis Client on EC2
sudo apt install redis-tools -y
Connect:
redis-cli -h <redis-endpoint>
Test:
SET name Aisalkyn
GET name
Demonstration
Simulate app behavior:
Without cache:
- Query DB 100 times
With Redis:
- First request → DB
- Others → Redis
Explain:
Real applications use Redis for:
- Login sessions
- API response caching
- Rate limiting
Comparison Table for Students
| Feature | RDS | Aurora | ElastiCache |
|---|---|---|---|
| Type | Managed DB | High-performance DB | Cache |
| Storage | Single DB | Distributed | In-memory |
| HA | Multi-AZ | Built-in distributed | Redis replication |
| Speed | Normal | Very Fast | Extremely Fast |
| Use Case | Standard apps | Enterprise apps | Speed optimization |
How DevOps Uses These Together
Example Architecture:
App in EKS → Redis (ElastiCache) → Aurora → S3 backups
CI/CD:
- Jenkins deploys app
- Terraform provisions RDS/Aurora
- Secrets Manager stores credentials
- CloudWatch monitors performance
Real Interview Question
Q: Why use ElastiCache if Aurora is fast?
Answer:
Aurora is fast for relational storage, but Redis is in-memory and much faster for frequent reads. It reduces database load and improves scalability.
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