IAM Roles and EC2 to S3 Access Simplified

On Day 8 of my #30DaysOfCloud journey, I went hands-on with IAM Roles and saw how an EC2 instance can access S3 without hardcoding any credentials.

This is a foundational AWS best practice — using IAM Roles for secure, temporary permissions.

🔄 Problem Statement

We want an EC2 instance to:

Access an S3 bucket (read/write)
Without using access keys or credentials
Securely using IAM Roles

🎭 What is an IAM Role?

An IAM Role is a set of permissions you can assign to AWS services.
Unlike IAM users, roles don’t have long-term credentials.

Instead, services like EC2 assume roles, and AWS automatically provides short-term access tokens to them.

💡 This is safer, more scalable, and follows best practices!

🔧 Step-by-Step: Allow EC2 to Access S3 Using IAM Role

1️⃣ Create an IAM Role

Go to IAM → Roles → Create Role
Select Trusted Entity: AWS service
Choose EC2 as the use case
Attach the policy: AmazonS3FullAccess (or create a custom policy for least privilege)
Name your role: EC2S3AccessRole
✅ Done! Role created.

2️⃣ Launch (or modify) an EC2 instance

Launch a new EC2 instance (or stop → modify an existing one)
Under "IAM Role", attach EC2S3AccessRole
Boot the instance and connect using SSH

3️⃣ Access S3 from EC2 (No Keys Needed!)

Log into your EC2 instance via SSH and test S3 access:

bashCopyEdit# List buckets
aws s3 ls

# Copy a file to S3
echo "Hello from EC2" > test.txt
aws s3 cp test.txt s3://your-bucket-name/

🚫 No access keys, no .aws/credentials needed — it works using role-based access!

🧪 How It Works (Under the Hood)

EC2 instance has metadata service (http://169.254.169.254) which provides temporary credentials
AWS CLI automatically uses those credentials
These are rotated automatically and scoped to the permissions defined in the role

✅ Best Practices

🔐 Use roles instead of access keys
🔄 Roles rotate credentials automatically
📦 Use least privilege — create scoped policies instead of S3FullAccess
🔍 Use CloudTrail to monitor access

🎯 Summary

IAM Roles are a cornerstone of cloud security and automation.

Today, I learned:

How to assign IAM roles to EC2
How EC2 accesses S3 securely
That roles > access keys in almost every case!

📚 Resources

🚀 Tomorrow: I’ll explore Amazon S3 in detail – buckets, object storage, lifecycle rules, and real-world use cases.

Let’s keep learning and building!
#30DaysOfCloud #AWS #IAM #EC2 #S3 #CloudSecurity #LearnInPublic #Hashnode #CloudJourney

✅ Day 8 of My Cloud Journey ☁ – IAM Roles + EC2 to S3 Access Without Credentials 🔐

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