S3 Bucket Policy Project 2: फक्त CloudFront OAC Access

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

1. रोजचा project story

Mei Lin (Singapore) व Suresh Reddy (Hyderabad) course videos. फक्त CloudFront URL.

Public-website नंतर: private + OAC.

2. OAC-only का?

हे का लागतं?

Public GetObject = CF controls bypass. OAC = फक्त CloudFront.

• Bucket private; BPA on
• OAC SigV4
• Service principal + SourceArn
• Direct URL 403

3. Policy काय?

हे काय आहे?

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowCloudFrontServicePrincipalRead",
      "Effect": "Allow",
      "Principal": { "Service": "cloudfront.amazonaws.com" },
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::rb-ott-origin-ap-south-1/*",
      "Condition": {
        "StringEquals": {
          "AWS:SourceArn": "arn:aws:cloudfront::111122223333:distribution/EDFDVBD6EXAMPLE"
        }
      }
    }
  ]
}

Line-by-line

1. Service principal.
2. GetObject.
3. Origin /*.
4. SourceArn lock.
5. No *.
6. Swap real id.

4. CLI + output

कसं करायचं (step by step)

# Private bucket
aws s3api create-bucket --bucket rb-ott-origin-ap-south-1 --region ap-south-1 \
  --create-bucket-configuration LocationConstraint=ap-south-1
aws s3api put-public-access-block --bucket rb-ott-origin-ap-south-1 --public-access-block-configuration \
  BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=true,RestrictPublicBuckets=true

# Create OAC, attach to distribution origin, note Distribution ARN, then:
aws s3api put-bucket-policy --bucket rb-ott-origin-ap-south-1 --policy file://oac.json
# (empty success)

echo demo-video-bytes > demo.mp4
aws s3 cp demo.mp4 s3://rb-ott-origin-ap-south-1/videos/demo.mp4

5. Allow आणि deny

# DENY — direct S3 (no CF)
curl -s -o /dev/null -w "%{http_code}\n" \
  https://rb-ott-origin-ap-south-1.s3.ap-south-1.amazonaws.com/videos/demo.mp4
# 403

# ALLOW — via CloudFront domain (after OAC attached)
curl -s -o /dev/null -w "%{http_code}\n" \
  https://d111111abcdef8.cloudfront.net/videos/demo.mp4
# 200

6. OAC vs OAI

7. Multi-industry

OTT, edtech, news, hospital training.

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. Lab: private origin + OAC

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

कसं करायचं (step by step)

1. Private bucket.
2. CF + OAC.
3. Policy + upload.
4. Deny+allow.

Cleanup (billing थांबवा)

1. Cleanup CF + bucket.
2. DNS cleanup.

10. सामान्य errors आणि fixes

प्रत्येक row = खरी चूक. Panic करण्याआधी fix वाचा.

11. 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.

12. FAQ

13. Interview Q&A

14. Tips — English, मराठी आणि हिंदी

15. 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.

16. 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.

17. 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

18. 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.

19. 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.

20. PR review checklist

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

उजळणी, मुलाखत आणि तुलना cards

हा lesson काही मिनिटांत revise करा. Cards phone वर save करा किंवा PNG download करा. प्रत्येक card वरचा QR हा lesson उघडतो.

अजून cards: Ravi Sir's Cards.