A bucket is private when you create it. Nobody outside your account can read an object, and the account's Block Public Access settings stop you from changing that by accident. Serving a website means changing it on purpose, in three steps.

1. Lift the block

aws s3api get-public-access-block --bucket monster-market-h7frlm
aws s3api put-public-access-block --bucket monster-market-h7frlm \
  --public-access-block-configuration BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=false,RestrictPublicBuckets=false

Four switches, all true by default. Two concern ACLs, an older mechanism this course leaves off. BlockPublicPolicy refuses any policy that would make the bucket public; RestrictPublicBuckets ignores such a policy if one exists. Both go to false for a website bucket.

2. Attach a bucket policy

A policy is a JSON document of statements. This is your first one; Chapter 2 has the full grammar.

{
  "Version": "2012-10-17",
  "Statement": [{
    "Sid": "PublicRead",
    "Effect": "Allow",
    "Principal": "*",
    "Action": "s3:GetObject",
    "Resource": "arn:aws:s3:::monster-market-h7frlm/*"
  }]
}

Effect allows. Principal * is anyone at all. Action s3:GetObject is reading an object, nothing else. Resource is every key in this bucket, by ARN. Save it as a file and attach it:

aws s3api put-bucket-policy --bucket monster-market-h7frlm --policy file://policy.json
aws s3api get-bucket-policy-status --bucket monster-market-h7frlm

file:// tells the CLI to read the parameter from a file. The status reports "IsPublic": true.

3. Turn on website hosting

aws s3 website s3://monster-market-h7frlm --index-document index.html --error-document error.html

The bucket now answers on its website endpoint, http://monster-market-h7frlm.s3-website-us-east-1.amazonaws.com. A request for / gets index.html; a missing key gets error.html with a 404.

curl -s http://monster-market-h7frlm.s3-website-us-east-1.amazonaws.com/

Before the policy, the same request returns 403 Forbidden. That is the difference the two steps make.