S3 Bucket Policy Project 1: Public Read-Only Static Website

By Ravindra Bagale, trainer · LinkedIn · Last updated: 28 October 2026

1. रोजचा project story

Ananya Sharma (जयपूर) व Lukas Weber (Berlin) static HTML. Principal "*" GetObject; Put/Delete = admin IAM. Ship, test, cleanup.

संबंधित survey: S3 bucket policy examples. इथे पूर्ण project lab.

2. ही policy का?

हे का लागतं?

Static files = public read, write बंद. त्याच bucket मध्ये PII = leak. वेगळा public bucket.

• कोणीही GET
• Anonymous PUT/DELETE नको
• Admin = IAM
• BPA: policy allow, ACL बंद

3. Policy काय आहे?

हे काय आहे?

Resource-based. एक Allow: Principal *, GetObject, BUCKET/*.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "PublicReadGetObject",
      "Effect": "Allow",
      "Principal": "*",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::rb-bakery-site-ap-south-1/*"
    }
  ]
}

Line-by-line

1. Version — सध्याची language.
2. Sid — review label.
3. Effect Allow.
4. Principal *.
5. फक्त GetObject.
6. Resource /*.

4. कसं करायचं (CLI + output)

कसं करायचं (step by step)

# Create bucket in Mumbai
aws s3api create-bucket --bucket rb-bakery-site-ap-south-1 --region ap-south-1 \
  --create-bucket-configuration LocationConstraint=ap-south-1
# {"Location": "http://rb-bakery-site-ap-south-1.s3.amazonaws.com/"}

# BPA: allow public policy; keep ACL blocks on
aws s3api put-public-access-block --bucket rb-bakery-site-ap-south-1 --public-access-block-configuration \
  BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=false,RestrictPublicBuckets=false

aws s3api put-bucket-policy --bucket rb-bakery-site-ap-south-1 --policy file://public-read.json
# (empty success)

echo "<h1>Menu - Priya Bakery Pune</h1>" > index.html
aws s3 cp index.html s3://rb-bakery-site-ap-south-1/index.html --content-type text/html
aws s3 website s3://rb-bakery-site-ap-south-1/ --index-document index.html --error-document index.html

5. Test: allow आणि deny

# ALLOW — anonymous GET
curl -s -o /dev/null -w "%{http_code}\n" \
  https://rb-bakery-site-ap-south-1.s3.ap-south-1.amazonaws.com/index.html
# 200

# DENY — anonymous PUT
curl -s -o /dev/null -w "%{http_code}\n" -X PUT --data hack \
  https://rb-bakery-site-ap-south-1.s3.ap-south-1.amazonaws.com/hack.txt
# 403

6. Multi-industry

Ecommerce, NGO, school, museum, QR menu.

7. Security checklist

• वेगळा public bucket; PII नको
• फक्त GetObject
• ACL block ठेवा
• नंतर CloudFront HTTPS

8. AccessDenied debugging आणि Policy Simulator

AccessDenied क्रम: BPA → bucket Deny → IAM Allow → KMS → VPCe → ACL. Simulator BPA/VPC/KMS miss करू शकतो — खऱ्या CLI ने test.

# Decode
aws s3api get-bucket-policy --bucket BUCKET --query Policy --output text | python3 -m json.tool
aws s3api get-public-access-block --bucket BUCKET
aws iam simulate-principal-policy --policy-source-arn ARN \
  --action-names s3:GetObject --resource-arns arn:aws:s3:::BUCKET/key.txt
aws cloudtrail lookup-events --lookup-attributes AttributeKey=EventName,AttributeValue=GetObject --max-items 5

9. Industries आणि roles

• Frontend sites
• DevOps as code
• Security review

10. Lab: public read-only bakery site

Org block नसेल तर ap-south-1 (Mumbai). आधी budget alert.

कसं करायचं (step by step)

1. Bucket create.
2. BPA + policy + upload.
3. Allow+deny proof.
4. Website endpoint.

Cleanup (billing थांबवा)

1. Cleanup bucket.
2. Account BPA restore.

11. सामान्य errors आणि fixes

प्रत्येक row = खरी चूक. Panic करण्याआधी fix वाचा.

12. Troubleshooting checklist

1. Region + endpoint.
2. Policy + BPA.
3. Lab user.
4. Sid binary search.
5. CloudTrail.
6. KMS test.
7. VPCe path.
8. Lock cleanup.

13. FAQ

14. Interview Q&A

15. Tips — English, मराठी आणि हिंदी

16. Policy save करण्याआधी checklist

1. Business rule एका वाक्यात.
2. Allow vs Deny-unless; Deny wins.
3. ARN shapes.
4. Condition keys.
5. BPA first.
6. Allow+deny plan.
7. Cleanup plan.
8. json.tool.

17. Policy Simulator walkthrough

Simulator identity/resource typos साठी चांगला; BPA/VPCe/KMS miss होऊ शकतात. नंतर खऱ्या path वरून CLI.

1. Simulator → user/role.
2. Action + ARN.
3. Include bucket policy.
4. CLI confirm.
5. Mismatch → layers.

18. Copy-paste runbook

# 0) Region + names
export AWS_REGION=ap-south-1
export BUCKET=rb-lab-$(date +%s)-ap-south-1

# 1) Create + show BPA
aws s3api create-bucket --bucket $BUCKET --region $AWS_REGION \
  --create-bucket-configuration LocationConstraint=$AWS_REGION
aws s3api get-public-access-block --bucket $BUCKET || true

# 2) Validate + apply policy
python3 -m json.tool policy.json >/dev/null
aws s3api put-bucket-policy --bucket $BUCKET --policy file://policy.json
aws s3api get-bucket-policy --bucket $BUCKET --query Policy --output text | python3 -m json.tool | head

# 3) Allow test + Deny test (fill per project)
# ... project-specific curls / aws s3 cp ...

# 4) Cleanup
aws s3 rm s3://$BUCKET --recursive || true
aws s3api delete-bucket-policy --bucket $BUCKET || true
aws s3api delete-bucket --bucket $BUCKET

19. Industry story bank

वरील प्रत्येक project एक industry story वापरतो. इतर industries मध्ये फक्त bucket/principal/Condition बदला.

• Healthcare: SSE-KMS + OrgID + MFA.
• Fintech: IP + HTTPS + OAC.
• EdTech: OAC only.
• Logistics: VPCe.
• Media: Object Lock.
• Retail: prefix public read.
• SaaS: prefix homes.
• Gov: OrgID + MFA + Lock.

20. AccessDenied debugging flowchart

1. Error code + request id.
2. Bucket + region.
3. BPA.
4. Explicit Deny.
5. Conditions.
6. KMS key policy.
7. OAC id.
8. VPCe path.
9. Simulator + CLI.
10. Support last.

21. PR review checklist

• Valid JSON.
• Required fields.
• No open write.
• Tests.
• Cleanup.

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अजून cards: Ravi Sir's Cards.