Merge pull request #2497 from ministryofjustice/pch-cloudfront-waf-ssm

prisoner-content-hub: implement IP-allowlisting

terraform/aws-accounts/cloud-platform-aws/account/cloudfront-waf.tf

@@ -0,0 +1,74 @@
+# This is a very specific AWS WAF implemention for use with CloudFront only
+# Users with an ingress must only utilise ModSecurity or the WAF-enabled centralised ingress
+# This WAF IPSet, rule, and corresponding WAF ACL is very specific to Prisoner Content Hub
+# who stream videos from an S3 bucket which is limited to access within a prison estate
+# Using AWS WAF is/was the only way to IP allowlist with CloudFront (as at 2023-10-12).
+# We should explore alternatives as they become available.
+
+# resource "aws_ssm_parameter" "prisoner_content_hub_production" {
+#   name  = "/prisoner-content-hub-production/ip-allow-list"
+#   type  = "String"
+#   value = "bar"
+# }
+
+# resource "aws_ssm_parameter" "prisoner_content_hub_staging" {
+#   name  = "/prisoner-content-hub-staging/ip-allow-list"
+#   type  = "String"
+#   value = "bar"
+# }
+
+# resource "aws_ssm_parameter" "prisoner_content_hub_development" {
+#   name  = "/prisoner-content-hub-development/ip-allow-list"
+#   type  = "String"
+#   value = "bar"
+# }
+
+data "aws_ssm_parameter" "test" {
+  name = "/prisoner-content-hub-test/ip-allow-list"
+}
+
+resource "aws_waf_ipset" "prisoner_content_hub" {
+  name = "prisoner-content-hub-production"
+
+  dynamic "ip_set_descriptors" {
+    for_each = tomap({
+      for k, v in tomap(jsondecode(nonsensitive(data.aws_ssm_parameter.test.value))) :
+      k => (length(split("/", v)) > 1) ? v : "${v}/32" # when we update to terraform 1.5.0, we can use strcontains()
+    })
+
+    content {
+      type  = "IPV4"
+      value = sensitive(ip_set_descriptors.value)
+    }
+  }
+}
+
+resource "aws_waf_rule" "prisoner_content_hub" {
+  name        = "prisoner_content_hub"
+  metric_name = "prisonerContentHub"
+
+  predicates {
+    data_id = aws_waf_ipset.prisoner_content_hub.id
+    negated = false
+    type    = "IPMatch"
+  }
+}
+
+resource "aws_waf_web_acl" "prisoner_content_hub" {
+  name        = "prisoner_content_hub"
+  metric_name = "prisonerContentHub"
+
+  default_action {
+    type = "BLOCK"
+  }
+
+  rules {
+    action {
+      type = "ALLOW"
+    }
+
+    priority = 1
+    rule_id  = aws_waf_rule.prisoner_content_hub.id
+    type     = "REGULAR"
+  }
+}