I often need to attach an IAM policy to a user which only let the user read the content of a specific bucket. For now, AWS does not offer a predefined policy for this, so here it is.

Replace the string bucketname with your bucket name in the following JSON.

{
  "Version":"2012-10-17",
  "Statement":[
    {
      "Effect":"Allow",
      "Action":[
        "s3:ListBucket",
        "s3:ListAllMyBuckets"
      ],
      "Resource":"arn:aws:s3:::*"
    },
    {
      "Effect":"Deny",
      "Action":[
        "s3:ListBucket"
      ],
      "NotResource":[
        "arn:aws:s3:::bucketname",
        "arn:aws:s3:::bucketname/*"
      ]
    },
    {
      "Effect":"Allow",
      "Action":[
        "s3:ListBucket",
        "s3:GetObject"
      ],
      "Resource":[
        "arn:aws:s3:::bucketname",
        "arn:aws:s3:::bucketname/*"
      ]
    }
  ]
}