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feat: Create custom rules #101

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feat: Create custom rules #101

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44 changes: 44 additions & 0 deletions examples/complete/main.tf
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Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,50 @@ module "waf" {
}
]

# Example from https://docs.aws.amazon.com/waf/latest/developerguide/waf-bot-control-example-user-agent-exception.html
custom_rules = [
{
name = "user_agent_match_rule"
priority = 1000
action = "block"

and_statement = [
{
type = "LabelMatchStatement"
statement = {
key = "awswaf:managed:aws:bot-control:signal:non-browser-user-agent"
scope = "LABEL"
}
},
{
type = "NotStatement"
statement = {
type = "ByteMatchStatement"
field_to_match = {
single_header = {
name = "user-agent"
}
}
positional_constraint = "EXACTLY"
search_string = "PostmanRuntime/7.29.2"
text_transformation = [
{
priority = 0
type = "NONE"
}
]
}
}
]

visibility_config = {
cloudwatch_metrics_enabled = true
sampled_requests_enabled = true
metric_name = "user_agent_match_rule"
}
}
]

rate_based_statement_rules = [
{
name = "rule-40"
Expand Down
145 changes: 145 additions & 0 deletions rules.tf
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,11 @@ locals {
) => rule
} : {}

custom_rules = local.enabled && var.custom_rules != null ? {
for rule in flatten(var.custom_rules) :
lookup(rule, "name", null) != null ? rule.name : format("%s-custom-rule-%d", module.this.id, rule.priority) => rule
} : {}

geo_allowlist_statement_rules = local.enabled && var.geo_allowlist_statement_rules != null ? {
for rule in flatten(var.geo_allowlist_statement_rules) :
format("%s-%s",
Expand Down Expand Up @@ -266,6 +271,146 @@ resource "aws_wafv2_web_acl" "default" {
}
}

dynamic "rule" {
for_each = local.custom_rules

content {
name = rule.value.name
priority = rule.value.priority

action {
dynamic "block" {
for_each = rule.value.action == "block" ? [1] : []
content {}
}
dynamic "count" {
for_each = rule.value.action == "count" ? [1] : []
content {}
}
}

statement {
dynamic "and_statement" {
for_each = lookup(rule.value, "and_statement", null) != null ? [rule.value.and_statement] : []

content {
statement {
dynamic "label_match_statement" {
for_each = [for item in and_statement.value : item.statement if lookup(item, "type", null) == "LabelMatchStatement"]

content {
key = label_match_statement.value.key
scope = label_match_statement.value.scope
}
}
}

statement {
dynamic "not_statement" {
for_each = [for item in and_statement.value : item.statement if lookup(item, "type", null) == "NotStatement"]

content {
statement {
dynamic "byte_match_statement" {
for_each = lookup(not_statement.value, "type", null) == "ByteMatchStatement" ? [not_statement.value] : []

content {
positional_constraint = byte_match_statement.value.positional_constraint
search_string = byte_match_statement.value.search_string

dynamic "field_to_match" {
for_each = lookup(byte_match_statement.value, "field_to_match", null) != null ? [byte_match_statement.value.field_to_match] : []

content {
dynamic "all_query_arguments" {
for_each = lookup(field_to_match.value, "all_query_arguments", null) != null ? [1] : []

content {}
}

dynamic "body" {
for_each = lookup(field_to_match.value, "body", null) != null ? [1] : []

content {}
}

dynamic "method" {
for_each = lookup(field_to_match.value, "method", null) != null ? [1] : []

content {}
}

dynamic "query_string" {
for_each = lookup(field_to_match.value, "query_string", null) != null ? [1] : []

content {}
}

dynamic "single_header" {
for_each = lookup(field_to_match.value, "single_header", null) != null ? [field_to_match.value.single_header] : []

content {
name = single_header.value.name
}
}

dynamic "single_query_argument" {
for_each = lookup(field_to_match.value, "single_query_argument", null) != null ? [field_to_match.value.single_query_argument] : []

content {
name = single_query_argument.value.name
}
}

dynamic "uri_path" {
for_each = lookup(field_to_match.value, "uri_path", null) != null ? [1] : []

content {}
}
}
}

dynamic "text_transformation" {
for_each = lookup(byte_match_statement.value, "text_transformation", null) != null ? [
for rule in lookup(byte_match_statement.value, "text_transformation") : {
priority = rule.priority
type = rule.type
}] : []

content {
priority = text_transformation.value.priority
type = text_transformation.value.type
}
}
}
}
}
}
}
}
}
}
}

dynamic "visibility_config" {
for_each = lookup(rule.value, "visibility_config", null) != null ? [rule.value.visibility_config] : []

content {
cloudwatch_metrics_enabled = lookup(visibility_config.value, "cloudwatch_metrics_enabled", true)
metric_name = visibility_config.value.metric_name
sampled_requests_enabled = lookup(visibility_config.value, "sampled_requests_enabled", true)
}
}

dynamic "rule_label" {
for_each = lookup(rule.value, "rule_label", null) != null ? rule.value.rule_label : []
content {
name = rule_label.value
}
}
}
}

dynamic "rule" {
for_each = local.geo_allowlist_statement_rules

Expand Down
47 changes: 46 additions & 1 deletion variables.tf
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,51 @@ variable "byte_match_statement_rules" {
DOC
}

variable "custom_rules" {
type = list(object({
name = string
priority = number
action = string
rule_label = optional(list(string), null)
and_statement = optional(any)
visibility_config = optional(object({
cloudwatch_metrics_enabled = optional(bool)
metric_name = string
sampled_requests_enabled = optional(bool)
}), null)
}))
default = null
description = <<-DOC
A rule statement that defines a custom rule for AWS WAF to apply to web requests.

action:
The action that AWS WAF should take on a web request when it matches the rule's statement.
name:
A friendly name of the rule.
priority:
If you define more than one Rule in a WebACL,
AWS WAF evaluates each request against the rules in order based on the value of priority.
AWS WAF processes rules with lower priority first.

rule_label:
A List of labels to apply to web requests that match the rule match statement

and_statement:
A logical rule statement used to combine other rule statements with AND logic.
See https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/wafv2_web_acl#and-statement

visibility_config:
Defines and enables Amazon CloudWatch metrics and web request sample collection.

cloudwatch_metrics_enabled:
Whether the associated resource sends metrics to CloudWatch.
metric_name:
A friendly name of the CloudWatch metric.
sampled_requests_enabled:
Whether AWS WAF should store a sampling of the web requests that match the rules.
DOC
}

variable "geo_allowlist_statement_rules" {
type = list(object({
name = string
Expand Down Expand Up @@ -580,7 +625,7 @@ variable "rate_based_statement_rules" {
field_to_match:
Part of a web request that you want AWS WAF to inspect.
positional_constraint:
Area within the portion of a web request that you want AWS WAF to search for search_string.
Area within the portion of a web request that you want AWS WAF to search for search_string.
Valid values include the following: `EXACTLY`, `STARTS_WITH`, `ENDS_WITH`, `CONTAINS`, `CONTAINS_WORD`.
search_string:
String value that you want AWS WAF to search for.
Expand Down