From 56bd3212f9a76f4dd747c00b2f8241ecde5aed94 Mon Sep 17 00:00:00 2001
From: bdeshi <bdeshi@bdeshi.space>
Date: Wed, 24 Aug 2022 11:32:17 +0600
Subject: [PATCH] support for peered vpn cidrs

---
 data.tf   | 39 ++++++++++++++++++++++++++++++++++++---
 locals.tf | 21 ++++++++++++++++++---
 2 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/data.tf b/data.tf
index 0239953..ce2c2b5 100644
--- a/data.tf
+++ b/data.tf
@@ -10,7 +10,6 @@ data "aws_subnet" "selected" {
 data "aws_ami" "selected" {
   most_recent = true
   owners      = ["amazon"]
-
   filter {
     name   = "name"
     values = ["amzn2-ami-*"]
@@ -19,10 +18,44 @@ data "aws_ami" "selected" {
 
 data "http" "relay_auth_key_response" {
   url = "https://api.tailscale.com/api/v2/tailnet/${var.tailscale_domain}/keys/${tailscale_tailnet_key.relay_auth.id}"
-
-  # Optional request headers
   request_headers = {
     Accept        = "application/json"
     Authorization = "Basic ${local.tailscale_auth_token}"
   }
 }
+
+data "aws_route_tables" "_subnet_filtered" {
+  filter {
+    name   = "association.subnet-id"
+    values = [var.subnet_id]
+  }
+}
+
+data "aws_route_table" "selected" {
+  route_table_id = (length(data.aws_route_tables._subnet_filtered.ids) > 0
+    ? data.aws_route_tables._subnet_filtered.ids[0]
+    : data.aws_vpc.selected.main_route_table_id
+  )
+}
+
+data "aws_vpc_peering_connections" "requested_peerings" {
+  filter {
+    name   = "requester-vpc-info.vpc-id"
+    values = [var.vpc_id]
+  }
+  filter {
+    name   = "status-code"
+    values = ["active"]
+  }
+}
+
+data "aws_vpc_peering_connections" "accepted_peerings" {
+  filter {
+    name   = "accepter-vpc-info.vpc-id"
+    values = [var.vpc_id]
+  }
+  filter {
+    name   = "status-code"
+    values = ["active"]
+  }
+}
diff --git a/locals.tf b/locals.tf
index 4cb0421..8bfb363 100644
--- a/locals.tf
+++ b/locals.tf
@@ -2,15 +2,30 @@ locals {
 
   tailscale_auth_token = base64encode("${var.tailscale_api_key}:")
 
-  # list of cidr routes: cidrs of selected vpc + additional cidrs if defined
+  vpc_peering_connections = setunion(
+    data.aws_vpc_peering_connections.requested_peerings.ids,
+    data.aws_vpc_peering_connections.accepted_peerings.ids
+  )
+
+  # list of cidr routes: cidrs of selected vpc + cidr of peers + additional cidrs if defined
   tailscale_routes = var.advertise_routes ? concat(
     data.aws_vpc.selected.cidr_block_associations[*].cidr_block,
+    [
+      for route in data.aws_route_table.selected.routes :
+      route.cidr_block if contains(
+        local.vpc_peering_connections,
+        route.vpc_peering_connection_id
+      )
+    ],
     length(var.additional_routes) > 0 ? var.additional_routes : []
   ) : []
 
-  # list of vpc dns servers: each vpc cidr base + 2 & fallback_nameservers if defined
+  # list of vpc dns servers: (cidr base + 2) for vpc cidrs + fallback_nameservers if defined
   tailscale_nameservers = var.advertise_nameservers ? concat(
-    [for cidr_block in data.aws_vpc.selected.cidr_block_associations : cidrhost(cidr_block.cidr_block, 2)],
+    [
+      for cidr_block in data.aws_vpc.selected.cidr_block_associations :
+      cidrhost(cidr_block.cidr_block, 2)
+    ],
     length(var.fallback_nameservers) > 0 ? var.fallback_nameservers : []
   ) : []