main.tf

locals {
  enabled             = module.this.enabled
  bucket_name         = var.bucket_name != null && var.bucket_name != "" ? var.bucket_name : module.this.id
  replication_enabled = local.enabled && var.s3_replication_enabled
  bucket_arn          = "arn:${data.aws_partition.current.partition}:s3:::${join("", aws_s3_bucket.default.*.id)}"

  # Deprecate `replication_rules` in favor of `s3_replication_rules` to keep all the replication related
  # inputs grouped under s3_replica[tion]
  s3_replication_rules = var.replication_rules == null ? var.s3_replication_rules : var.replication_rules

  public_access_block_enabled = var.block_public_acls || var.block_public_policy || var.ignore_public_acls || var.restrict_public_buckets
}

resource "aws_s3_bucket" "default" {
  #bridgecrew:skip=BC_AWS_S3_13:Skipping `Enable S3 Bucket Logging` because we do not have good defaults
  #bridgecrew:skip=CKV_AWS_52:Skipping `Ensure S3 bucket has MFA delete enabled` due to issue in terraform (https://github.com/hashicorp/terraform-provider-aws/issues/629).
  #bridgecrew:skip=BC_AWS_S3_16:Skipping `Ensure S3 bucket versioning is enabled` because dynamic blocks are not supported by checkov
  #bridgecrew:skip=BC_AWS_S3_14:Skipping `Ensure all data stored in the S3 bucket is securely encrypted at rest` because variables are not understood
  #bridgecrew:skip=BC_AWS_GENERAL_56:Skipping `Ensure that S3 buckets are encrypted with KMS by default` because we do not have good defaults
  count               = local.enabled ? 1 : 0
  bucket              = local.bucket_name
  acl                 = try(length(var.grants), 0) == 0 ? var.acl : null
  force_destroy       = var.force_destroy
  tags                = module.this.tags
  acceleration_status = var.transfer_acceleration_enabled ? "Enabled" : null

  dynamic "versioning" {
    for_each = var.versioning_enabled ? [true] : []
    content {
      enabled = true
    }
  }

  dynamic "lifecycle_rule" {
    for_each = var.lifecycle_rules
    content {
      enabled                                = lifecycle_rule.value.enabled
      prefix                                 = lifecycle_rule.value.prefix
      tags                                   = lifecycle_rule.value.tags
      abort_incomplete_multipart_upload_days = lifecycle_rule.value.abort_incomplete_multipart_upload_days

      dynamic "noncurrent_version_expiration" {
        for_each = lifecycle_rule.value.enable_noncurrent_version_expiration ? [1] : []

        content {
          days = lifecycle_rule.value.noncurrent_version_expiration_days
        }
      }

      dynamic "noncurrent_version_transition" {
        for_each = lifecycle_rule.value.enable_glacier_transition ? [1] : []

        content {
          days          = lifecycle_rule.value.noncurrent_version_glacier_transition_days
          storage_class = "GLACIER"
        }
      }

      dynamic "noncurrent_version_transition" {
        for_each = lifecycle_rule.value.enable_deeparchive_transition ? [1] : []

        content {
          days          = lifecycle_rule.value.noncurrent_version_deeparchive_transition_days
          storage_class = "DEEP_ARCHIVE"
        }
      }

      dynamic "transition" {
        for_each = lifecycle_rule.value.enable_glacier_transition ? [1] : []

        content {
          days          = lifecycle_rule.value.glacier_transition_days
          storage_class = "GLACIER"
        }
      }

      dynamic "transition" {
        for_each = lifecycle_rule.value.enable_deeparchive_transition ? [1] : []

        content {
          days          = lifecycle_rule.value.deeparchive_transition_days
          storage_class = "DEEP_ARCHIVE"
        }
      }



      dynamic "transition" {
        for_each = lifecycle_rule.value.enable_standard_ia_transition ? [1] : []

        content {
          days          = lifecycle_rule.value.standard_transition_days
          storage_class = "STANDARD_IA"
        }
      }

      dynamic "expiration" {
        for_each = lifecycle_rule.value.enable_current_object_expiration ? [1] : []

        content {
          days = lifecycle_rule.value.expiration_days
        }
      }
    }
  }

  dynamic "logging" {
    for_each = var.logging == null ? [] : [1]
    content {
      target_bucket = var.logging["bucket_name"]
      target_prefix = var.logging["prefix"]
    }
  }

  # https://docs.aws.amazon.com/AmazonS3/latest/dev/bucket-encryption.html
  # https://www.terraform.io/docs/providers/aws/r/s3_bucket.html#enable-default-server-side-encryption
  server_side_encryption_configuration {
    rule {
      apply_server_side_encryption_by_default {
        sse_algorithm     = var.sse_algorithm
        kms_master_key_id = var.kms_master_key_arn
      }
    }
  }

  dynamic "website" {
    for_each = var.website_inputs == null ? [] : var.website_inputs
    content {
      index_document           = website.value.index_document
      error_document           = website.value.error_document
      redirect_all_requests_to = website.value.redirect_all_requests_to
      routing_rules            = website.value.routing_rules
    }
  }

  dynamic "cors_rule" {
    for_each = var.cors_rule_inputs == null ? [] : var.cors_rule_inputs

    content {
      allowed_headers = cors_rule.value.allowed_headers
      allowed_methods = cors_rule.value.allowed_methods
      allowed_origins = cors_rule.value.allowed_origins
      expose_headers  = cors_rule.value.expose_headers
      max_age_seconds = cors_rule.value.max_age_seconds
    }
  }

  dynamic "grant" {
    for_each = try(length(var.grants), 0) == 0 || try(length(var.acl), 0) > 0 ? [] : var.grants

    content {
      id          = grant.value.id
      type        = grant.value.type
      permissions = grant.value.permissions
      uri         = grant.value.uri
    }
  }

  dynamic "replication_configuration" {
    for_each = local.replication_enabled ? [1] : []

    content {
      role = aws_iam_role.replication[0].arn

      dynamic "rules" {
        for_each = local.s3_replication_rules == null ? [] : local.s3_replication_rules

        content {
          id       = rules.value.id
          priority = try(rules.value.priority, 0)
          # `prefix` at this level is a V1 feature, replaced in V2 with the filter block.
          # `prefix` conflicts with `filter`, and for multiple destinations, a filter block
          # is required even if it empty, so we always implement `prefix` as a filter.
          # OBSOLETE: prefix   = try(rules.value.prefix, null)
          status = try(rules.value.status, null)

          destination {
            # Prefer newer system of specifying bucket in rule, but maintain backward compatibility with
            # s3_replica_bucket_arn to specify single destination for all rules
            bucket             = try(length(rules.value.destination_bucket), 0) > 0 ? rules.value.destination_bucket : var.s3_replica_bucket_arn
            storage_class      = try(rules.value.destination.storage_class, "STANDARD")
            replica_kms_key_id = try(rules.value.destination.replica_kms_key_id, null)
            account_id         = try(rules.value.destination.account_id, null)

            dynamic "access_control_translation" {
              for_each = try(rules.value.destination.access_control_translation.owner, null) == null ? [] : [rules.value.destination.access_control_translation.owner]

              content {
                owner = access_control_translation.value
              }
            }
          }

          dynamic "source_selection_criteria" {
            for_each = try(rules.value.source_selection_criteria.sse_kms_encrypted_objects.enabled, null) == null ? [] : [rules.value.source_selection_criteria.sse_kms_encrypted_objects.enabled]

            content {
              sse_kms_encrypted_objects {
                enabled = source_selection_criteria.value
              }
            }
          }

          # Replication to multiple destination buckets requires that priority is specified in the rules object.
          # If the corresponding rule requires no filter, an empty configuration block filter {} must be specified.
          # See https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/s3_bucket
          dynamic "filter" {
            for_each = try(rules.value.filter, null) == null ? [{ prefix = null, tags = {} }] : [rules.value.filter]

            content {
              prefix = try(filter.value.prefix, try(rules.value.prefix, null))
              tags   = try(filter.value.tags, {})
            }
          }
        }
      }
    }
  }

  dynamic "object_lock_configuration" {
    for_each = var.object_lock_configuration != null ? [1] : []
    content {
      object_lock_enabled = "Enabled"
      rule {
        default_retention {
          mode  = var.object_lock_configuration.mode
          days  = var.object_lock_configuration.days
          years = var.object_lock_configuration.years
        }
      }
    }
  }
}

module "s3_user" {
  source  = "cloudposse/iam-s3-user/aws"
  version = "0.15.7"

  enabled      = local.enabled && var.user_enabled
  s3_actions   = var.allowed_bucket_actions
  s3_resources = ["${join("", aws_s3_bucket.default.*.arn)}/*", join("", aws_s3_bucket.default.*.arn)]

  context = module.this.context
}

data "aws_partition" "current" {}

data "aws_iam_policy_document" "bucket_policy" {
  count = local.enabled ? 1 : 0

  dynamic "statement" {
    for_each = var.allow_encrypted_uploads_only ? [1] : []

    content {
      sid       = "DenyIncorrectEncryptionHeader"
      effect    = "Deny"
      actions   = ["s3:PutObject"]
      resources = ["${local.bucket_arn}/*"]

      principals {
        identifiers = ["*"]
        type        = "*"
      }

      condition {
        test     = "StringNotEquals"
        values   = [var.sse_algorithm]
        variable = "s3:x-amz-server-side-encryption"
      }
    }
  }

  dynamic "statement" {
    for_each = var.allow_encrypted_uploads_only ? [1] : []

    content {
      sid       = "DenyUnEncryptedObjectUploads"
      effect    = "Deny"
      actions   = ["s3:PutObject"]
      resources = ["${local.bucket_arn}/*"]

      principals {
        identifiers = ["*"]
        type        = "*"
      }

      condition {
        test     = "Null"
        values   = ["true"]
        variable = "s3:x-amz-server-side-encryption"
      }
    }
  }

  dynamic "statement" {
    for_each = var.allow_ssl_requests_only ? [1] : []

    content {
      sid       = "ForceSSLOnlyAccess"
      effect    = "Deny"
      actions   = ["s3:*"]
      resources = [local.bucket_arn, "${local.bucket_arn}/*"]

      principals {
        identifiers = ["*"]
        type        = "*"
      }

      condition {
        test     = "Bool"
        values   = ["false"]
        variable = "aws:SecureTransport"
      }
    }
  }

  dynamic "statement" {
    for_each = length(var.s3_replication_source_roles) > 0 ? [1] : []

    content {
      sid = "CrossAccountReplicationObjects"
      actions = [
        "s3:ReplicateObject",
        "s3:ReplicateDelete",
        "s3:ReplicateTags",
        "s3:GetObjectVersionTagging",
        "s3:ObjectOwnerOverrideToBucketOwner"
      ]
      resources = ["${local.bucket_arn}/*"]
      principals {
        type        = "AWS"
        identifiers = var.s3_replication_source_roles
      }
    }
  }

  dynamic "statement" {
    for_each = length(var.s3_replication_source_roles) > 0 ? [1] : []

    content {
      sid       = "CrossAccountReplicationBucket"
      actions   = ["s3:List*", "s3:GetBucketVersioning", "s3:PutBucketVersioning"]
      resources = [local.bucket_arn]
      principals {
        type        = "AWS"
        identifiers = var.s3_replication_source_roles
      }
    }
  }

  dynamic "statement" {
    for_each = keys(var.privileged_principal_arns)

    content {
      sid     = "AllowPrivilegedPrincipal[${statement.key}]" # add indices to Sid
      actions = var.privileged_principal_actions
      resources = distinct(flatten([
        "arn:${data.aws_partition.current.partition}:s3:::${join("", aws_s3_bucket.default.*.id)}",
        formatlist("arn:${data.aws_partition.current.partition}:s3:::${join("", aws_s3_bucket.default.*.id)}/%s*", var.privileged_principal_arns[statement.value]),
      ]))
      principals {
        type        = "AWS"
        identifiers = [statement.value]
      }
    }
  }
}

data "aws_iam_policy_document" "aggregated_policy" {
  count         = local.enabled ? 1 : 0
  source_json   = var.policy
  override_json = join("", data.aws_iam_policy_document.bucket_policy.*.json)
}

resource "aws_s3_bucket_policy" "default" {
  count      = local.enabled && (var.allow_ssl_requests_only || var.allow_encrypted_uploads_only || length(var.s3_replication_source_roles) > 0 || length(var.privileged_principal_arns) > 0 || var.policy != "") ? 1 : 0
  bucket     = join("", aws_s3_bucket.default.*.id)
  policy     = join("", data.aws_iam_policy_document.aggregated_policy.*.json)
  depends_on = [aws_s3_bucket_public_access_block.default]
}

# Refer to the terraform documentation on s3_bucket_public_access_block at
# https://www.terraform.io/docs/providers/aws/r/s3_bucket_public_access_block.html
# for the nuances of the blocking options
resource "aws_s3_bucket_public_access_block" "default" {
  count  = module.this.enabled && local.public_access_block_enabled ? 1 : 0
  bucket = join("", aws_s3_bucket.default.*.id)

  block_public_acls       = var.block_public_acls
  block_public_policy     = var.block_public_policy
  ignore_public_acls      = var.ignore_public_acls
  restrict_public_buckets = var.restrict_public_buckets
}

# Per https://docs.aws.amazon.com/AmazonS3/latest/userguide/about-object-ownership.html
resource "aws_s3_bucket_ownership_controls" "default" {
  count  = local.enabled ? 1 : 0
  bucket = join("", aws_s3_bucket.default.*.id)

  rule {
    object_ownership = var.s3_object_ownership
  }
  depends_on = [time_sleep.wait_for_aws_s3_bucket_settings]
}

# Workaround S3 eventual consistency for settings objects
resource "time_sleep" "wait_for_aws_s3_bucket_settings" {
  count            = local.enabled ? 1 : 0
  depends_on       = [aws_s3_bucket_public_access_block.default, aws_s3_bucket_policy.default]
  create_duration  = "30s"
  destroy_duration = "30s"
}